Physical effects

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This article attempts to break down the potential physical effects induced by psychoactive substances into simple, easy to understand titles, descriptions and levelling systems. This is done without depending on metaphors, analogies or personal trip reports. The article starts off with descriptions of the most simple effects and works its way up towards more complex experiences as it progresses. For more subjective effect components, see our complete index.



Appetite enhancement

Main article: Appetite enhancement

Appetite enhancement can be described as the simple experience of increased hunger, appetite and an enhancement of one's own sense of taste. This effect occurs on certain substances such as mirtazapine and cannabis and is often referred to colloquially as "the munchies."

Bodily control enhancement

Bodily control enhancement can be described as an effect which induces a dramatic increase in a person's control over their physical body. This results in the ability to accurately control a greater variety of muscles across one's body with the tiniest of precise mental triggers.

It is often interpreted by people as a profound and primal feeling of being put back in touch with the animal body.

Perception of bodily heaviness

Perception of bodily heaviness can be described as feelings of the body becoming extremely heavy. This can result in one's body feeling as if it is difficult, uncomfortable, or sometimes impossible to move, resulting in feelings of slowness and sluggishness. This effect indirectly encourages feelings of sedation by making it uncomfortable or difficult to move.


Main article: Stimulation

Stimulation can be defined as any changes in a person's energy levels which are interpreted as encouraging when it comes to movement and physical activities such as running, walking, cleaning, socializing, dancing, and climbing.


Physical stimulation can be broken into two basic forms:

  • Forced stimulation - This can be described as the effects of increased energy becoming so pronounced that (at higher dosages) the user will experience uncontrollable physical shaking, jaw clenching and tremors should they choose to ignore the stimulation and remain still.
  • Encouraged stimulation - This can be described as feeling extremely energetic but in a purely controllable fashion that does not overwhelm the user with involuntary movements should they choose to stop expending large amounts of energy.

Tactile enhancement

Main article: Tactile enhancement

Tactile enhancement can be described as an overall increase in both the intensity of a person's sense of touch and their awareness of the physical sensations across their body. At its highest level, this becomes extreme enough that the exact location and current sensation of every single nerve ending across one's skin can be felt and comprehended all at once. In contrast, throughout normal sober living, most people can only maintain awareness of the tactile sensations which are relevant to their current situation.

This effect can result in tactile sensations such as touching, hugging, kissing, and sex becoming greatly enhanced in terms of the pleasure they induce. However, it can also result in an over-sensitivity of the skin which causes the same sensations to become uncomfortable and overwhelming.

Tactile enhancement is often accompanied by other coinciding effects such as spontaneous tactile sensations and physical euphoria. It is most commonly induced under the influence of moderate dosages of psychedelic compounds, such as LSD, psilocybin, and mescaline. However, it can also occur under the influence of stimulants, cannabinoids, and certain dissociatives.

Stamina enhancement

Main article: Stamina enhancement

Stamina enhancement can be described as an increase in one's ability to engage in physically and mentally taxing activities without the development of fatigue. Although this effect is commonly mistaken for stimulation, it differs as it is not a direct increase in one's energy levels. Instead, it is an increase in one's resilience in performing an activity and a mitigation of general fatigue.

Psychoactive substances that directly increase one's endurance without stimulation are known as actoprotectors. These are are defined as "substances that enhance body stability against physical or mental loads without increasing oxygen consumption or heat production."[1]


Appetite suppression

Main article: Appetite suppression

Appetite suppression can be described as a decreased sensation of appetite and a reduction in food consumption. When experiencing this effect, one's desire or craving for food is partially to completely suppressed. Depending on the intensity, this can result in complete disinterest, disgust, and physical discomfort (such as Nausea) concerning food, sometimes resulting in a person going days without eating. In cases of severe appetite suppression, it is often easier for one to drink beverages, such as protein shakes, in order to receive the nutrition needed to function. If substances which induce this effect are used for prolonged periods of time weight loss often occurs as a result.

Appetite suppression is a physical side effect of many drugs including stimulants (such as amphetamine, methylphenidate, nicotine, caffeine, cocaine, and modafinil), psychedelics, opioids, and many common selective serotonin reuptake inhibitors (SSRIs).

Cough suppression

Main article: Cough suppression

Cough suppression is a common effect which can be described as a decrease in the desire to cough. This can be a positive effect which either suppresses a pre-existing cough or allows an individual to inhale large amounts of smoke without having the desire to cough. This effect commonly can occur on DXM, opioids such as codeine, and anticholinergics such as promethazine.

Perception of decreased weight

Perception of bodily lightness can be described as feelings of the body becoming extremely light and easy to move. This indirectly encourages stimulation, resulting in feelings of increased energy and a general sense of bounciness as the body becomes weightless and therefore effortless to move.

Motor control loss

Main article: Motor control loss

Motor control loss can be defined as a suppression of the process by which humans and other animals organize and execute their physical actions. Fundamentally, it is the integration of sensory information (both about the world and the current state of the body) to determine the appropriate set of muscle forces and joint activations to generate some desired movement or action. This process requires cooperative interaction between the central nervous system and the musculoskeletal system, and is thus the result of a combination of information processing, coordination, mechanics, physics, and cognition. Successful motor control is crucial to interacting with the world; it not only determines action capabilities, but regulates balance and stability as well.

In terms of hallucinogenic drugs, although in certain contexts these substances can actually enhance motor control through the component known as increased bodily control, it's worth noting that more often than not they simply decrease it.

The experience of motor control loss ranges between subtle and all-encompassing in its effects as at lower levels it simply results in a general sense of difficulty when performing physical tasks involving dexterity, walking, and balance. At higher levels, however, this component moves beyond subtle in its effects and becomes capable of completely disabling one's ability to use any level of fine or gross motor control. This results in catatonic states and the inability to perform any task beyond lying or sitting down regardless of the person's current cognitive capabilities.

Nausea suppression

Main article: Nausea suppression

Nausea suppression can be described as a physical effect which induces the mitigation of nausea and stomach cramps as a direct result of ingesting specific psychoactive substances.

Pain relief

Main article: Pain relief

Pain relief can be described as an effect which suppresses negative sensations such as aches and pains. This can be done either by blocking the painful sensation from one's conscious faculties or by covering the sensation over with feelings of physical and cognitive euphoria.

Common examples of drugs which induce this effect include alcohol, opioids such as heroin, codeine or morphine and NMDA receptor antagonists such as ketamine and MXE.

Respiratory depression

Respiratory depression is a common physical side effect of many central nervous system depressants such as opioids, GHB, benzodiazepines (in combination with other depressants) and alcohol. This effect is manifested as a reduced urge to breathe and can cause a "sighing" pattern of breathing which can be described as deep breaths separated by abnormally long pauses. Sedation increases along with drug-induced respiratory depression. Breathing is controlled in the brain by the medulla oblongata, and when the activity of it is suppressed by drugs it decreases the ability to ventilate.[2]

This effect can be potentially life-threatening when depressants are taken in large doses or when combined with one another. In an overdose situation, an individual may cease breathing entirely (go into respiratory arrest) which is rapidly fatal without treatment.

Substance induced respiratory depression can be broken down into 4 separate levels of intensity which progressively intensify proportional to dosage:

  1. Minimal respiratory depression: Minimal respiratory depression occurs on low doses of depressants. This effect is unnoticeable and is accompanied by mild sedation.
  2. Moderate respiratory depression: As the dose increases, feelings of sedation intensify from moderate to high levels. One becomes aware of the sensation that the breath is slowed down mildly to moderately or that one is taking less breaths per minute than usual. This level of respiratory depression is not uncomfortable and does not result in any shortness, struggling, or impairment of breath.
  3. Severe respiratory depression: Severe respiratory depression is impairing and occurs at dangerously high doses of depressants. At this level, a person's breathing rate becomes noticeably slowed down significantly which results in the feeling that one is not adequately moving air in and out of the body. Severe respiratory depression induces a powerful and overwhelming focus point of attention on one's breathing rate. In terms of how this feels physically, it can be described as the feeling that you are breathing abnormally, are short of breath, cannot breathe in enough air, and/or are forced to breathe manually in a conscious effort to feel that you are taking in enough air. Extreme sedation is present and if sleep occurs one may potentially wake up struggling and gasping for air. In cases of GHB overdoses, many reportedly experience an abnormal pattern of breathing characterized by progressively deeper and sometimes faster breathing, followed by a gradual decrease that results in a temporary stop in breathing called an apnea. Confusion and anxiety often occur at this level of heightened awareness, increasing the strong sensation that one's breathing will stop completely due to sleep or a lack of attention.
  4. Respiratory failure: At this point, a person's oxygen and carbon dioxide levels become dangerously impaired. The person goes into a semi-conscious state, loses consciousness completely, slips into a coma, and/or stops breathing completely (respiratory arrest). The skin, fingernails, or lips may have a blue-ish color to them. This level of respiratory failure can be fatal without immediate medical attention.[3] Opioids, in overdose or combined with other depressants, are notorious for such fatalities.


To prevent death, it is recommended to contact emergency medical services immediately in case of severe respiratory depression. If caused by an opioid overdose, an opioid antagonist, such as naloxone, should be administered. Many harm reduction organizations provide naloxone to users for free or it can be bought at pharmacies (including Walgreens and CVS in the U.S.). Naloxone will rapidly reverse the respiratory depression unless complicated by other depressants. For other drug-induced respiratory depression, hospitalization and the assistance of a mechanical breathing machine may be necessary.


Main article: Sedation

Sedation can be defined as the experience of decreased agitation, sensory input, and alertness which occurs under the influence of certain drugs. Depending on the level of intensity, it results in feelings of general relaxation and a loss of energy. This effect differs itself from sleepiness outright for its physical over mental effect.

In terms of response to sensory input, sedation can broken down into four separate levels which are defined below:

  1. Minimal sedation - At this level, one will respond normally to verbal/tactile stimuli despite feeling a little sedated.
  2. Moderate sedation - At this level, one will respond to verbal/tactile stimulation only if it is particularly prominent or above usual noise levels.
  3. Deep sedation - At this level, one will respond only to repeated or painful stimulation.
  4. General anesthesia - At this level, one is unarousable even with repeated painful stimulus.

Seizure suppression

Main article: Seizure suppression

Seizure suppression is an effect caused by drugs known as anticonvulsants. These drugs prevent or reduce the severity and frequency of seizures in various types of epilepsy. The different types of anticonvulsants may act on different receptors in the brain and have different modes of action.

Two mechanisms that appear to be important in anticonvulsants are an enhancement of GABA action and inhibition of sodium channel activity. Other mechanisms are the inhibition of calcium channels and glutamate receptors.

Tactile suppression

Main article: Tactile suppression

Tactile suppression can be described as a decrease in one's ability to feel their sense of touch in a manner which can result a general numbness across the body. At higher levels, this can eventually increase to the point where physical sensations have been completely blocked and the body is fully anesthetized.

Tactile suppression is often accompanied by other coinciding effects such as pain relief and physical euphoria. It is most commonly induced under the influence of moderate dosages of dissociative compounds, such as ketamine, PCP, and DXM. However, it can also occur under the influence of opioids and certain GABAergic depressants.

Novel effects

Bodily pressures

Main article: Bodily pressures

Bodily pressures can be described as the physical experience of spontaneous pressures across differing parts of the body. These can occur as static and fixed in their location or they can occur at seemingly random varying points across the body. Depending on the intensity of the sensation, this can result in pressures which range from neutral in experience to extremely uncomfortable in experience.


Main article: Bronchodilation

Bronchodilation is the expansion of the bronchial air passages in the respiratory tract. A bronchodilator is a substance that dilates the bronchial tubes, resulting in decreased resistance in the respiratory airway and increased airflow to the lungs.

Additionally some psychostimulant drugs that have an amphetamine-like mode of action, such as amphetamine,[4] methamphetamine, and cocaine,[5] have bronchodilating effects and were used often for asthma due to the lack of effective β2-agonists for use as bronchodilator, but are now rarely, if ever, used medically for their bronchodilation effect.

Changes in felt bodily form

Changes in felt bodily form can be described as feelings of a change in physical perception which can manifest itself as sensations of the body shifting in its perceived felt physical shape, organization and form without any visual alterations. For example, perfectly comfortable feelings of the body folding into itself many times over as well as stretching, splitting into separate parts, expanding, or condensing into, over, and across itself in extremely complex forms are all entirely possible.

Changes in gravity

Main article: Changes in gravity

Changes in felt gravity can be described as feelings of gravity shifting in its direction. For example, during this state one may feel as if they are flying forwards, backwards, upwards, downwards, in multiple directions at once, or in a singular direction that doesn't make sense.

This effect is most common throughout high level experiences with cannabis, salvinorin a and certain other hallucinogens, particularly during states of level 5 or above geometry and holes, spaces and voids.

Excessive yawning

Main article: Excessive yawning

Excessive yawning can be described as a physical effect which induces repeated and spontaneous yawning despite a complete absense of sedation or sleepiness. The experience of this effect most commonly occurs on hallucinatory tryptamines such as psilocin, psilocybin, psilacetin, 4-HO-MET and others.

Muscle relaxation

Main article: Muscle relaxation

Muscle relaxation can be described as the experience of one's muscles losing rigidity or tenseness and becoming relaxed and comfortable. This component is particularly useful for those who are currently suffering from muscle or back pains and is commonly associated with benzodiazepines.

Physical autonomy

Main article: Physical autonomy

Physical autonomy can be described as the experience of one's own body performing simple or complex actions entirely of its own accord. Depending on the intensity, this results in any required task becoming partially to completely autonomous in nature without the requirement of decision-making skills or attentive conscious input.

At lower levels, the effect is partially controllable by commanding the body with simple thoughts. For example, thoughts such as "go to the toilet" or "go drink a glass of water" can result in the body performing these actions flawlessly when the person would otherwise struggle endlessly due to a lack of focus and motor control had they have attempted to perform it manually in their given state. This can often help the person perform necessary physical actions such as tending to bodily functions or avoiding danger when they would otherwise be too incapable, unconscious, or distractible to perform them.

At higher levels, this effect no longer requires verbal commands and becomes entirely automatic. It's worth noting that although this technically results in a loss of cognitive control, the body will usually only perform actions which the owner would have decided to perform were they capable of it themselves, but can (on rare occasions) result in random or unwanted physical actions and movements.

Physical euphoria

Main article: Physical euphoria

Physical euphoria is an effect which exists in contrast to cognitive euphoria but usually occurs simultaneously along side of it. It can be described as feelings of physical pleasure and comfort within and across the body. The forcefulness of this effect can range between subtle in its strength to overwhelmingly pleasurable beyond even the most intense full body orgasm possible.

This effect occurs consistently under the influence of certain substances, these commonly include opioids such as heroin or codeine and stimulants such as amphetamine and MDMA.

Pupil constriction

Main article: Pupil constriction

Pupil constriction (also called pinpoint pupils or miosis) is the reduction of the size of a person's pupils under normal lighting conditions. Pupil constriction decreases a person's ability to see in low light conditions. This effect generally occurs on opioids.

Pupil dilation

Main article: Pupil dilation

Pupil dilation (also called mydriasis) is the enlargement of the size of a person's pupils under normal lighting conditions. Normally, the pupil size increases in the dark and shrinks in the light; however, a dilated pupil will remain excessively large even in a bright environment. This effect generally occurs on drugs which increase overall serotonin levels including psychedelics, dissociatives, deliriants, entactogens, various stimulants and some anti-depressants.

Runny nose

Main article: Runny nose
Above is an image which depicts a child with a runny nose.

Runny nose is a condition where the nasal cavity is filled with a significant amount of mucus fluid. The condition, commonly known as a "runny nose", occurs relatively frequently in most human beings. It is a common symptom of allergies or certain diseases, such as the common cold or hay fever.

It can be a side effect of crying, exposure to cold temperatures, cocaine abuse[6], withdrawal (such as from opioids like methadone[7]) and under the influence psychedelic tryptamines such as psilocin, psilocybin and psilacetin.

Skin flushing

Main article: Skin flushing

Skin flushing can be described as the experience of a sudden reddening of the skin which is usually accompanied by feelings of rushing blood and warm skin. It is a common physical response to anxiety, stress, embarrassment, anger and certain psychoactive substances. In terms of its appearance, it manifests itself in an identical fashion to that which occurs across the face when one is embarrassed. Blotchiness or solid patches of redness are also often visible when blushing.

Sublingual numbing

Main article: Sublingual numbing

Mouth numbing is a physical side effect of administering certain drugs sublingually (under the tongue) or buccally. This effect can be described as an obvious feeling of general numbness of the tongue and mouth which can stay for up to an hour after the drug has been administered.

The NBOMe series (25C-NBOMe, 25B-NBOMe, and 25I-NBOMe) cause this effect consistently and it is accompanied by a strong, unpleasant, metallic chemical taste immediately after sublingual absorption. As LSD does not cause numbing or a strong chemical taste, this is the key difference when it comes to determining whether your blotter paper contains LSD or another psychoactive chemical such as one of the NBOMe series.

The stimulant cocaine also causes numbing of the tongue, gums, and mouth when administered sublingually. Many people test the purity of their cocaine by rubbing it in their mouth. This, however, is not a guarantee of the drug's quality as it is common for cocaine to be cut with various numbing agents and local anesthetics (such as procaine, AKA novocaine, lidocaine, or benzocaine) which mimic or add to cocaine's numbing effect.

Spontaneous tactile sensations

Spontaneous physical sensations can be described as the experience of sensations across the body occurring without any obvious or immediate physical trigger. This results in feelings of seemingly random but distinct tingling sensations that occur across the skin and within the body. Depending on the psychoactive substance consumed, these vary greatly in their alternative styles of sensation but can be broken down into three basic levels of intensity. These are described and documented below:

  1. Mild - At the lowest level, the sensation can be described as subtle and fleeting tingling sensations throughout the body. These sensations do not impair physical motor control and can essentially be ignored if one wishes to do so.
  2. Distinct - At this level, the sensation becomes very difficult to ignore. It can be described as distinct tingling sensations which are intense enough to partially impair a person’s motor control and act as a significant distraction which impairs one's focus.
  3. Overwhelming – At the highest level, the tingling sensations increase enough to become a powerful, uncontrollable focus point of the person's attention. This can feel completely overwhelming and heavily impairs a person's motor control, leaving them either lying or sitting down, incapable of standing up due to the all-encompassing sensations.

Spontaneous physical sensations are often accompanied by other coinciding effects such as tactile enhancement and physical euphoria. They are most commonly induced under the influence of moderate dosages of psychedelic compounds, such as LSD, psilocybin, and mescaline. However, they can also occur under the influence of stimulants, cannabinoids, and dissociatives.


The specific differences between each potential style of spontaneous tactile sensations can be broken down into the following variations:

  • Moving vs. Motionless – Spontaneous physical sensations will either move up and down various parts of the body in different directions or they will remain still and consistent in their position.
  • Constant vs. Spontaneous – Spontaneous physical sensations will either be constantly present throughout a significant portion of the experience or they will spontaneously and temporarily manifest themselves at random points for differing lengths of time.
  • Sharp vs. Soft – Spontaneous physical sensations will either be perceived to feel soft, warm, and gentle on the skin or sharp, cold, and electric.
  • All-encompassing vs. Location specific - Spontaneous physical sensations can either be felt across every square inch of the skin in an evenly distributed fashion or in very specific locations such as the ends of the fingers and toes, up and down the spinal column or throughout the head.
  • Euphoric vs. Dysphoric – At appropriately high dosages, spontaneous physical sensations can either be interpreted as pleasurable to experience or they can manifest in the opposite direction and become uncomfortable to experience.

Tactile hallucinations

Tactile hallucinations or somatic hallucinations can be described as the experience of perceiving physical sensations which are not actually occurring within reality. Common examples of these can include hallucinating the feeling of people or insects touching the body in various places and in a wide variety of ways. Alternatively, these hallucinations can be felt as complex and structured arrangements of vibration across the skin.

This effect may also be accompanied by visual hallucinations. For example, during internal and external hallucinations a person may have the perception that they are able to feel imagined objects or be touched by autonomous entities in a similar manner to that of ordinary dreams. The sensations that are possible within these hallucinations could be almost anything and can even include pain or sexual pleasure.

Tactile hallucinations are most commonly induced under the influence of heavy dosages of deliriant compounds, such as DPH, datura, and benzydamine. However, they can also occur to a lesser extent under the influence of psychedelics, stimulant psychosis and extreme sleep deprivation.

Optical sliding

Main article: Optical sliding

Optical sliding can be described as a physical effect which inhibits the coordination and control of one's eyes by suppressing their ability to keep them still. This results in the orientation of one's eyes continuously moving in a variety of directions and the sensation of not being able to stare motionless at any particular point becoming present.


Main article: Vasodilation

Vasodilation refers to the widening of blood vessels resulting from the relaxation of smooth muscle cells within the vessel walls (in particular in the large veins, large arteries, and smaller arterioles). In essence, the process is the opposite of vasoconstriction, which is the narrowing of blood vessels. The primary function of vasodilation is to increase blood flow in the body to tissues that need it most.

THC and other cannabinoids cause vasodilation by decreasing blood pressure; this dilates the blood vessels and increases blood flow throughout the body. The arteries in the eyeball expand from the decreased blood pressure and this often results in a bloodshot red eye effect and relief from glaucoma.[8][9]

Watery eyes

Main article: Watery eyes

Watery eyes can be described as a physical effect which results in a state of continuous involuntary streaming, tearing, crying and watering of the tear ducts within one's eyes.

The experience of this effect often leads onto the feeling that one is crying for no reason despite a complete absence of the relevant emotions one would usually expect during such a state. This is most common and intense within tryptamine psychedelics such as psilocin, psilocybin and psilacetin.

Uncomfortable effects

Abnormal heartbeat

Main article: Abnormal heartbeat

An abnormal heartbeat (also called an arrhythmia or dysrhythmia) is any of a group of conditions in which the electrical activity of the heart is irregular.

The heartbeat may be too fast (over 100 beats per minute) or too slow (less than 60 beats per minute) and may be regular or irregular. A heartbeat that is too fast is called tachycardia, and a heartbeat that is too slow is called bradycardia. Although many arrhythmias are not life-threatening, some can cause cardiac arrest.

Much like class 1b antiarrhythmics, cocaine is well known to be a voltage-gated sodium ion channel blocker, which may cause potentially fatal arrhythmias such as ventricular tachycardias and QT interval elongation at higher doses.[10] Parasympatholytics such as atropine block the vagal effects of acetylcholine on the sinoatrial node, often resulting in sinus tachycardia, hence atropine is often used clinically for symptomatic bradycardia.[citation needed]

In the context of substance usage, many compounds alter one's heartrate. For example, stimulants tend to increase one's heart rate whilst depressants tend to decrease it. Combining the two can often result in dangerously irregular heartbeats.


Main article: Constipation

Constipation refers to bowel movements that are infrequent or hard to pass. It usually results in painful defecation and small, compact feces. Constipation is a common side effect of opioids. Symptoms of opioid-induced constipation may be reduced by increasing the amount of dietary fruit, fiber and water consumed. Laxatives may also be used for temporary relief.

Decreased heart rate

Main article: Decreased heart rate
This picture shows sinus bradycardia seen in lead II with a heart rate of about 50.

Decreased heart rate or bradycardia is described as a heart rate that is lower than the normal heart rate at rest. The average healthy human heart normally beats 60 to 100 times a minute when a person is at rest. When the heart rate fluctuates to lower levels under 60 BPM, it is described as bradycardia or an abnormally low heart rate.

It can also be a psychological effect, such as a natural response to feelings of relaxation and serenity. This is a common effect of sedating substances especially depressants such as benzodiazepines or opioids.


Main article: Dehydration

Dehydration can be defined as any excessive loss of bodily water within a living organism which results in an accompanying disruption of metabolic processes. Besides an uncomfortably dry mouth and feelings of general thirstiness, symptoms of dehydration may include headaches, decreased blood pressure (hypotension), and dizziness or fainting when standing up. Untreated dehydration generally results in delirium, unconsciousness, swelling of the tongue, and (in extreme cases) death.

In relation to the consumption of psychoactive substances, mild dehydration is common under the influence of many different drugs, particularly stimulants. At moderate levels, this can be generally described as a sense of consistent and uncomfortable thirst throughout the duration of the experience which necessitates sipping at a drink to maintain fluid levels and to avoid an uncomfortably dry mouth. At extreme levels (which generally only occur with the use of deliriants), these experiences of dehydration become so powerful that one may find themselves with painfully dry eyes and mucus membranes, rendering them incapable of swallowing due to excessive and unquenchable thirst.

Water intoxication

It's important to note that regardless of how dehydrated one may become under the influence of any substance, careful effort and consideration should always be put into ensuring that one does not drink water excessively as it can result in a state known as water intoxication. This can be potentially fatal and is classed as a disturbance in brain functions that results when the normal balance of electrolytes in the body is pushed outside of safe limits by over-hydration. Although extremely rare, there have been a few notable deaths which were clearly triggered by the excessive overconsumption of water under the influence of drug-induced dehydration. The average toxic dosage of water in a human being is roughly ten litres, however, this can be easily avoided by simply sipping at water and making a conscious effort to not drink unnecessarily large amounts.


Main article: Diarrhea
A type 6 - 7 stool can be classified as diarrhea.

Diarrhea or diarrhoea is the condition of having at least three loose or liquid bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. This can progress to decreased urination, loss of skin color, a fast heart rate, and a decrease in responsiveness as it becomes more severe.

In the context of psychoactive substance usage, certain compounds have been known induce to diarrhea or can at least increase the likelihood of it occurring. This is not as dangerous as the same condition when it occurs through infection as it only remains whilst one is under the influence of the drug.

Difficulty urinating

Main article: Difficulty urinating

Difficulty urinating also known as urinary retention, can be defined as the experience of a decreased ability to pass urine. This can be due to painful burning sensations within the urethra or a simple lack of bladder control which prevents or inhibits one from urinating even with a full bladder.


Main article: Dizziness

Dizziness can be defined as the experience of the perception of motion (usually a spinning motion). It is often associated with nausea and vomiting as well as a loss of motor control, causing a difficulty standing or walking.

The medical literature lists three types of dizziness:

  1. Objective - The first is known as objective and describes when the patient has the sensation that objects in the environment are moving.
  2. Subjective - The second is known as subjective and refers to when the patient feels as if he or she is moving.
  3. Psuedovertigo - The third is known as pseudovertigo, an intensive sensation of rotation inside the patient's head.

Frequent urination

Main article: Frequent urination

Frequent urination, or urinary frequency, can be defined as the need to urinate more often than usual. It is often, though not necessarily, associated with urinary incontinence and large total volumes of urine. However, in other cases, urinary frequency involves only normal volumes of urine overall.

In the context of substance usage, many compounds result in the need to urinate excessively. This can be triggered by dehydration resulting in the consumption of large amounts of water or it can be a direct result of the substance itself.


Main article: Headaches

A headache can be described as a pain anywhere in the region of the head or neck. It can be a symptom of a number of different conditions. The brain tissue within the skull itself is not sensitive to pain because it lacks pain receptors. Rather, the pain is caused by disturbance of the pain-sensitive structures around the brain.

In the context of substance usage, the overuse of certain substances can cause painful headaches, particularly during the offset of the experience and if the user is dehydrated or has not eaten enough food.

Increased heart rate

Main article: Increased heart rate
Heartrate above 100BPM
Increased heart rate or tachycardia is described as a heart rate that is faster than the normal heart rate at rest. The average healthy human heart normally beats 60 to 100 times a minute when a person is at rest.[11] When the heart rate fluctuates to higher levels over 100 BPM, it is described as tachychardia or an abnormally high heart rate.

This is a common effect of stimulating substances especially stimulants as a direct result of dopaminergic or adrenergic modulation.[12][13] It can also be a psychological effect, such as a natural adrenal response to shock or fear. As awareness is heightened, such responses often become more heightened, especially with astonishing or confusing hallucinations. Other mechanisms for increased heart rate exist as well, such as deliriants effect as an acetylcholine inhibitor, one of the main modulaters of heart rate in the peripheral nervous system.[14][15]

Increased perspiration

Increased perspiration, or hyperhidrosis, can be described as a condition characterized by increased sweat which is in excess of that required for the regulation of body temperature.

Increased perspiration is a hallmark symptom of sympathetic arousal (the "fight-or-flight" response) and is a common effect of stimulant drugs. Any psychoactive drug which exerts considerable serotonergic, dopaminergic, or adrenergic effects may cause increased perspiration. It is also a common symptom of benzodiazepine and alcohol withdrawal.[16] Cholinergics and, to a lesser extent, opioids have been additionally implicated in causing this as well.[citation needed]

Increased blood pressure

Increased blood pressure is a condition in which the pressure in the arteries is elevated to abnormal levels.

This effect is commonly experienced on stimulating and vasoconstricting drugs such as amphetamines and phenethylamine psychedelics.

Increased bodily temperature

Increased bodily temperature or pyrexia (which includes fever and hyperthermia) is defined as having a bodily temperature above normal baseline.[17] The typical average temperature of a person is around 37°C (98.6°F). While there is no agreed upon value in which pyrexia is labeled, it ranges between 37.5 - 38.3°C (99.5 - 100.9°F).[18] It is frequently associated with increased perspiration (sweating).

Pyrexia that exceeds 41.5°C (106.7°F) is labeled as hyperpyrexia and is a medical emergency potentially resulting in physical injury, long-term side effects, and death.[19]

Elevated body temperature can be classed into two different cases:

  • Fever is used to describe the body raising its core temperature due to illness. For example, a fever may be caused by a bacterial infection.
  • Hyperthermia is classified as an uncontrollable increase in body temperature that typically originates from an external source. This most frequently involves heat strokes or the use of certain drugs.

A large number of drugs in multiple classes are capable of causing this effect, and thermoregulation is a complex process involving many physiological systems and is therefore very common. Serotonin and 5-HT receptors[20], dopamine and D receptors[21] and norepinephrine[22] have a significant effect.


Main article: Itchiness

Itchiness is the sensation that causes a person the desire or reflex to scratch at their skin. Substances such as opioids, that activate histamine receptors or trigger histamine release can cause this effect. A way to counteract the itchiness in cases of substance use is to take an antihistamine such as DPH (Diphenhydramine).

Muscle cramps

Main article: Muscle cramps

Muscle cramps can be defined as an involuntary temporary strong muscle contraction or overshortening which may cause severe aches and pains. Usually the onset is sudden while the cramp resolves spontaneously in a few seconds to minutes.

In the context of substance usage, certain compounds induce muscle cramps which, depending on the drug, can range from mild to extremely uncomfortable in their intensity and are rare to frequent in their consistency.

Muscle spasms

Main article: Muscle spasms

Muscle spasms can be described as an experience where one undergoes a sudden involuntary contraction of a muscle or a group of muscles.

The term most commonly refers to a muscle cramp which may be accompanied by a sudden burst of pain, but is usually harmless and ceases after a few minutes. There are a variety of other causes of involuntary muscle contractions which may be more serious, depending on the cause.


Main article: Nausea

Nausea is a sensation of unease and discomfort in the upper stomach with an involuntary urge to vomit. It often, but not always, precedes vomiting.

In the context of substance usage, nausea and vomiting can occur as a result of stomach irritation through the consumption of materials which it is not used to digesting such as chemical powders or plant matter. Alternatively it may occur as a direct result of how the particular drug affects the brain and is therefore inseparable from the experience itself regardless of the method of consumption. This effect usually occurs at the onset of the experience and dissipates as the peak takes its toll.

Physical fatigue

Main article: Physical fatigue

Physical fatigue (or muscle fatigue) is the temporary physical inability of the muscles to perform optimally. It is a side effect characterized by feelings of tiredness and weakness. It can occur after prolonged physical exertion and extended periods of wakefulness. People who are fatigued may find it difficult to complete physical actions and may not be capable of getting out of bed or performing everyday household tasks. It can generally be treated with a period of rest or sleep.

Cognitive fatigue, the mental equivalent of this component, frequently occurs simultaneously alongside of physical fatigue.


Main article: Photophobia

Photophobia can be described as a symptom of abnormal physical intolerance to the visual perception of light. As a medical symptom, photophobia is not a morbid fear or psychological phobia, but an experience of discomfort or pain to the eyes due to light exposure or by presence of actual physical sensitivity of the eyes.

In terms of hallucinogen usage, this component is usually triggered by the way in which substance induced pupil dilation disables the eye's ability to adjust itself accordingly depending on current levels of light exposure.

Restless leg syndrome

Main article: Restless leg syndrome

Restless legs (also known as restless legs syndrome or RLS) is a neurological disorder characterized by an irresistible urge to move one's body to stop uncomfortable or odd sensations. It most commonly affects the legs, but can affect the arms, torso, head, and even phantom limbs. Moving the affected body part modulates the sensations, providing temporary relief.

RLS sensations range from pain or an aching in the muscles to "an itch you can't scratch", an unpleasant "tickle that won't stop", or even a crawling feeling. The sensations typically begin or intensify during quiet wakefulness, such as when relaxing, reading, studying, or trying to sleep.

In the context of substance usage, certain compounds induce states of restless leg syndrome throughout the experience of them. This can be mild in its effects or extremely intense and uncomfortable. Opiate withdrawal can produce this effect as well.


Main article: Salivation

Salivation can be described as the production and excretion of excess salivatory fluid as mediated by both the sympathetic and peripheral nervous system.[23][24] Salivation is a common side effect induced by a wide array of substances, but is most common with sedating substances and depressants. Salivation can also be triggered psychologically, such as through pleasant odors or pleasurable foods.


Main article: Seizure
Generalized 3 Hz spike and wave discharges in EEG during a seizure

An epileptic seizure (colloquially a fit) is a brief episode of signs and/or symptoms due to abnormal, excessive, or synchronous neuronal activity in the brain.[25] The outward effect can vary from uncontrolled jerking movement (tonic-clonic seizure) to as subtle as a momentary loss of awareness (absence seizure). The disease of the brain characterized by an enduring predisposition to generate epileptic seizures is called epilepsy,[26][27] but seizures can also occur in people who do not have epilepsy.

This can occur due to a variety of causes and is common during withdrawals from prolonged chronic benzodiazepine or alcohol usage or during an overdose on certain substances such as stimulants, synthetic cannabinoids and the 25x-NBOMe series of psychedelics. It has also been noted that opioid overdoses can cause seizures. This is believed to happen because many opioids, despite being depressants, have significant intrinsic activity at the sigma receptors.

Stomach cramps

Main article: Stomach cramps

Stomach cramps can be described as intense feelings of sudden pain or discomfort which occur as a result of directly ingesting psychoactive compounds and/or the materials which they reside within.

This effect is usually accompanied by prolonged periods of nausea and can therefore be mitigated using the same techniques.

Temporary erectile dysfunction

Temporary erectile dysfunction is an effect which occurs under the influence of certain substances in various degrees of intensity. It can be described as a difficulty in achieving and maintaining an adequate erect penis for the purpose of sexual intercourse. This effect is often induced by moderate to high dosages of stimulating substances due to the way in which they affect one's blood flow.

Temperature regulation suppression

Temperature regulation suppression can be defined as an inability to maintain a normal temperature. This results in feelings of constantly fluctuating between being uncomfortably cold and uncomfortably hot. It varies in its intensity between different substances but is particularly common within stimulating compounds.

Teeth grinding

Main article: Teeth grinding

Teeth grinding (also known as bruxism or jaw clenching) is a fairly common effect mostly associated with stimulants and stimulating psychedelics. It can be described as a compulsive and often uncontrollable urge to grind one's teeth. In extreme cases, this can result in painful damage to one's tongue, teeth and inner cheek.

The most effective methods for quickly alleviating uncomfortable bruxism include using chewing gum or a baby's pacifier (also called a dummy) to occupy one's jaws without causing damage. Magnesium (preferably glycinate) is also very effective at alleviating bruxism when it is taken at a dosage of 200mg once 6 hours before and again at 1-3 hours before ingesting a stimulant such as MDMA or amphetamine.[28]


Main article: Vasoconstriction

Vasoconstriction is the narrowing of the blood vessels resulting from contraction of the muscular wall of the vessels (in particular the large arteries and small arterioles). The process is the opposite of vasodilation, the widening of blood vessels.

Subjective side effects of vasoconstriction include feelings of tightness within one's arms and legs. It occurs under the influence of certain substances and can range from mild in its effects to extremely uncomfortable.

See also


  1. The Pharmacology of Actoprotectors: Practical Application for Improvement of Mental and Physical Performance ( / NCBI) |
  2. Opioids and the control of respiration |
  3. What Is Respiratory Failure? |
  4. Substance Abuse: A Comprehensive Textbook |
  5. Dominic Streatfeild (17 June 2003). Cocaine: An Unauthorized Biography |
  6. Palatal necrosis due to cocaine abuse ( / NCBI) |
  7. Eileen Trigoboff; Kneisl, Carol Ren; Wilson, Holly Skodol (2004). Contemporary psychiatric-mental health nursing. Upper Saddle River, N.J: Pearson/Prentice Hall. p. 274. ISBN 0-13-041582-0.
  8. Cardiovascular Effects of Cannabis |
  9. Is Marijuana an Effective Treatment for Glaucoma? |
  10. O’Leary, Michael E, and Jules C Hancox. “Role of Voltage-Gated Sodium, Potassium and Calcium Channels in the Development of Cocaine-Associated Cardiac Arrhythmias.” British Journal of Clinical Pharmacology 69.5 (2010): 427–442. PMC. Web. 27 June 2017.
  17. Fever (Wikipedia) |
  18. Hyperthermia (Wikipedia) |
  19. Hyperpyrexia |
  20. Serotonin and thermoregulation |
  21. Dopamine and thermoregulation |
  22. Thermoregulation and Norepinephrine |
  25. Epileptic seizures and epilepsy: definitions proposed by the International League Against Epilepsy (ILAE) and the International Bureau for Epilepsy (IBE) ( / NCBI) |
  26. Epileptic seizures and epilepsy: definitions proposed by the International League Against Epilepsy (ILAE) and the International Bureau for Epilepsy (IBE) ( / NCBI) |
  27. ILAE official report: a practical clinical definition of epilepsy ( / NCBI) |
  28. Rollsafe - Safety and Supplements for MDMA/Ecstasy/X |