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Lysergic acid diethylamide (LSD)
The skeletal formula of Lysergic acid diethylamide.
Threshold 20 µg
Light 25 - 75 µg
Common 50 - 150 µg
Strong 150 - 400 µg
Heavy 400+ µg
Total duration 10 - 12 hrs
Onset / Initial effects 20 - 60 mins
Coming up 1 - 2 hrs
Peak 3 - 6 hrs
Coming down 3 - 5 hrs
After effects 2 - 5 hrs

Lysergic acid diethylamide (abbreviated LSD or LSD-25 and also known as lysergide, acid, or lucy) is a semisynthetic psychedelic drug of the lysergamide family. LSD is non-addictive, is not known to cause brain damage, and has extremely low toxicity relative to dose.[1]

LSD was first synthesized by Albert Hofmann in 1938 from ergotamine, a chemical derived from ergot (a grain fungus that typically grows on rye). The short form "LSD" comes from its early code name LSD-25 which is an abbreviation for the German "Lysergsäure-diethylamid" followed by a sequential number.[2]

LSD is sensitive to oxygen, ultraviolet light, and chlorine[3], especially in solution, though its potency may last for years if it is stored away from light and moisture at low temperature. A perfect example of this for the average user is simply within a dark airtight container in a drawer or between the pages of a book. LSD does not need need to be kept in freezing cold conditions to maintain its potency.

In pure form, it is a colorless, odorless, and tasteless solid.[4] LSD is typically delivered orally, usually on a substrate such as absorbent blotter paper (or "tabs"), a sugar cube, or gelatin. In its liquid form, it can also be administered sublingually and by intramuscular or intravenous injection. LSD is very potent with 20–30 Micrograms(µg) (micrograms) being the threshold dose.[5] For reference purposes, this is physically smaller in terms of size than one tenth of a grain of sand.


LSD, or lysergic acid diethylamide, is a semi-synthetic drug of the lysergamide family. Lysergamides are distinct from both tryptamines and phenethylamines, although the chemical structure is more similar to tryptamine then phenethylamine.


LSD acts as a 5-HT1A, 5-HT2A, 5-HT2B, 5-HT2C, 5-HT5 and 5-HT6 partial agonist. The psychedelic effects are believed to come from LSD's efficacy at the 5-HT2A receptors. There is also efficacy at all dopamine receptors and all adrenoreceptors.

Subjective effects

Physical effects

The physical effects of LSD can be broken down into five components all of which progressively intensify proportional to dosage. These are described below and generally include:

  • Spontaneous tactile sensations - The body high of LSD can be described as proportionally very intense in comparison to its accompanying visual and cognitive effects. It behaves as a euphoric, fast moving, sharp and location specific tingling sensation. For some it is manifested spontaneously at different unpredictable points throughout the trip, but for most it maintains a steady presence that rises with the onset and hits its limit once the peak has been reached. At moderate to high doses of LSD, this sensation will usually hit its highest level and become so overwhelming that people find themselves writhing on the floor in complete pleasure.
  • Stimulation - In terms of its effects on the physical energy levels of the tripper, LSD is usually considered to be very energetic and stimulating without being forced. For example, when taken in any environment it will usually encourage physical activities such as running, walking, climbing or dancing. In comparison, other more commonly used psychedelics such as psilocin are generally sedating and relaxed.
  • Nausea - Mild nausea is occasionally reported when consumed in moderate to high dosages and either passes instantly once the tripper has vomited or gradually fades by itself as the peak sets in.
  • Increased bodily control
  • Enhancement of touch - Feelings of enhanced tactile sensation are consistently present at moderate levels throughout most LSD trips. Once Level 7A visuals are reached, an intense sensation of suddenly becoming aware of and being able to feel every single nerve ending across a person's entire body all at once is consistently present.

Cognitive effects

The cognitive effects of LSD can be broken down into ten components all of which progressively intensify proportional to dosage. In comparison to other psychedelics such as Psilocin, LSA and Ayahuasca, LSD is significantly more stimulating and fast paced in terms of the specific style of thought stream which it produces and contains a large number of potential effects.

The most prominent of these cognitive effects generally include:

Visual effects


LSD presents a full and complete array of visual enhancements which generally include:


LSD presents a full and complete array of visual enhancements which generally include:


The visual geometry that is present throughout this trip can be described as more similar in appearance to that of 2C-B or 2C-I than Psilocin, LSA or DMT. They can be comprehensively described as unstructured in their organization, algorithmic and digital in geometric style, intricate in complexity, large in size, fast and smooth in motion, multicoloured in scheme, bright and flat in colour and sharp in their edges with extremely angular corners. At higher dosages, they consistently result in states of Level 7A visual geometry.

Hallucinatory states

LSD is capable of producing a full range of low and high level hallucinatory states in a fashion that is significantly less consistent and reproducible than that of many other commonly used psychedelic. These effects include:

  • External hallucinations
  • Internal hallucinations - Although LSD is technically capable of producing of hallucinatory states in a fashion that is on par with psilocin or DMT in its vividness and intensity, in comparison, these effects are extremely rare and inconsistent. Whilst traditional psychedelics such as LSA, Ayahuasca and Mescaline will induce internal hallucinations near consistently at level 5 geometry and above, LSD will for most simply go straight into Level 7A visual geometry. This lack of consistently induced hallucinatory breakthroughs means that for most, LSD is simply not as deep of an experience as certain other psychedelics.

Auditory effects

The auditory effects of LSD are common in their occurrence and exhibit a full range of effects which commonly includes:

Studied therapeutic uses

End-of-life anxiety

From 2008 to 2011 there was ongoing research in Switzerland into using LSD to alleviate anxiety for terminally ill cancer patients coping with their impending deaths. Preliminary results from the study are promising and no negative effects have been reported.[6][7]


Some studies in the 1960s that used LSD to treat alcoholism reduced levels of alcohol misuse in almost 60% of those treated, an effect which lasted six months but disappeared after a year. [8][9] A 1998 review was inconclusive.[10]However, a 2012 meta-analysis of six randomized controlled trials found evidence that a single dose of LSD in conjunction with various alcoholism treatment programs was associated with a decrease in alcohol abuse, lasting for several months.[11]


LSD was studied in the 1960s by Eric Kast as an analgesic for serious and chronic pain caused by cancer or other major trauma.[12]

Even at low (sub-psychedelic) dosages, it was found to be at least as effective as traditional opiates, while being much longer lasting in pain reduction (lasting as long as a week after peak effects had subsided). Kast attributed this effect to a decrease in anxiety; that is to say that patients were not experiencing less pain, but rather were less distressed by the pain they experienced. This reported effect is being tested, though not using LSD, in an ongoing (as of 2006) study of the effects of psilocin on anxiety in terminal cancer patients.

Cluster headaches

LSD has been used as a treatment for cluster headaches, an uncommon but extremely painful disorder. Researcher Peter Goadsby describes the headaches as "worse than natural childbirth or even amputation without anesthetic."

Although the phenomenon has not been formally investigated, case reports indicate that LSD and psilocin can reduce cluster pain and also interrupt the cluster headache cycle, preventing future headaches from occurring. Currently existing treatments include various ergolines, among other chemicals, so LSD's efficacy may not be surprising. A dose-response study testing the effectiveness of both LSD and psilocin was planned at McLean Hospital, although the current status of this project is unclear. A 2006 study by McLean researchers interviewed 53 cluster headache sufferers who treated themselves with either LSD or psilocin, finding that a majority of the users of either drug reported beneficial effects. [13]

Unlike use of LSD or MDMA in psychotherapy, this research involves non-psychological effects and often sub-psychedelic dosages.[14][15]

Available Forms

LSD can be found in a number of forms.

  • Liquid form is often found in vials with a pipette. Liquid LSD is often dropped into the mouth or onto the tongue. There should not be a bitter metallic taste which numbs the mouth, as this instead indicates presence of a 25x-NBOMe compound.
  • Tablets and "Microdots" are very small tablets which are swallowed.
  • Blotters are sheets of blotting paper that are dipped into an LSD/alcohol solution which are then either swallowed or chewed sublingually. There should not be a bitter metallic taste which numbs the mouth when chewing the blotters, as this instead indicates presence of a 25x-NBOMe compound.
  • Powder can be taken orally, sublingually, via injection or insufflation.
  • Gel tabs can be taken orally and are small pieces of gelatin which contain LSD. These have become less common, but are still occasionally present in some areas.

Toxicity and Harm Potential

Radar plot showing relative physical harm, social harm, and dependence of LSD[16]

Similar to other psychedelic drugs, there are relatively few physical side effects associated with LSD acute exposure. Various studies have shown that in reasonable doses in a careful context, it presents no negative cognitive, psychiatric or toxic physical consequences of any sort.

Lethal Dosage

The median lethal dose or dosage at which 50% of participants die (LD50) of LSD for human beings has never been reached in any setting and is predicted to be roughly 12,000 micrograms, based on studies involving rats whereas the active dosage is between 100 and 500 micrograms. This means that assuming a person has unusually potent tabs, each of which are 200 micrograms in strength each, they would have to consume at least 60 of them to reach a potentially lethal dosage. Keep in mind that your average tab of LSD found on the street is 100 micrograms or less in strength and anything stronger than this is particularly rare.

Tolerance and Addiction Potential

LSD is non-habit-forming and the desire to use it can actually decrease with use. It is most often self-regulating. You also build an almost immediate tolerance to LSD after ingestion, preventing you from experiencing its full effects more often than every 4-7 days, unless you increase your dose significantly.

Legal issues

  • International: The UN 1971 Convention on Psychotropic Substances requires its parties to prohibit LSD. Hence, it is illegal in all parties to the convention, which includes the United States, Australia, New Zealand, and most of Europe. Medical and scientific research with LSD in humans is permitted under the 1971 UN Convention.
  • Canada: LSD is a Schedule III drug.
  • UK: LSD is a class A drug.
  • USA: LSD is a Schedule I drug.

See Also


  1. The Pharmacology of Lysergic Acid Diethylamide: a Review |
  2. LSD - My Problem Child by Albert Hoffman |
  3. Alexander and Ann Shulgin. "LSD", in TiHKAL -
  4. LSD - My Problem Child by Albert Hoffman |
  5. Psychopathology and Psychophysiology of Minimal LSD-25 Dosage |
  6. Psychiater Gasser bricht sein Schweigen |
  7. Landmark Clinical LSD Study Nears Completion |
  8. LSD "helps alcoholics to give up drinking" |
  9. Maclean, J.R.; Macdonald, D.C.; Ogden, F.; Wilby, E., "LSD-25 and mescaline as therapeutic adjuvants." In: Abramson, H., Ed., The Use of LSD in Psychotherapy and Alcoholism, Bobbs-Merrill: New York, 1967, pp. 407–426; Ditman, K.S.; Bailey, J.J., "Evaluating LSD as a psychotherapeutic agent," pp.74–80; Hoffer, A., "A program for the treatment of alcoholism: LSD, malvaria, and nicotinic acid," pp. 353–402.
  10. Treatment of alcoholism using psychedelic drugs: a review of the program of research |
  11. Lysergic acid diethylamide (LSD) for alcoholism: meta-analysis of randomized controlled trials |
  12. Attenuation of anticipation: a therapeutic use of lysergic acid diethylamide |
  13. Response of cluster headache to psilocin and LSD |
  14. Summarized from "Research into psilocin and LSD as cluster headache treatment" and the Clusterbusters website. Pages accessed 2007-01-31.
  15. Berlin pilot cluster headaches treatment with LSD study. LSD Alleviates 'Suicide Headaches'.
  16. Development of a rational scale to assess the harm of drugs of potential misuse |