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Summary sheet: N-Acetylcysteine
Chemical Nomenclature
Common names N-Acetylcysteine
Substitutive name (2R)-2-acetamido-3-sulfanylpropanoic acid
Class Membership
Psychoactive class Nootropic
Chemical class Cysteine
Routes of Administration

WARNING: Always start with lower doses due to differences between individual body weight, tolerance, metabolism, and personal sensitivity. See responsible use section.

Bioavailability 4%[1]
Threshold 100 mg
Light 400 - 600 mg
Common 600 - 1000 mg
Strong 1000 - 1500 mg
Heavy 1500 mg +
Total 3 - 6 hours
Onset 20 - 60 minutes

DISCLAIMER: PW's dosage information is gathered from users and resources for educational purposes only. It is not a recommendation and should be verified with other sources for accuracy.


N-Acetylcysteine (also known as Acetylcysteine, N-Acetyl-L-cysteine, or commonly as NAC) is a substituted amino acid which is primarily used as a medication for treating acetaminophen (also known as Paracetamol, and the brand-name Tylenol) overdose and to loosen thick mucus in the treatment of cystic fibrosis or chronic obstructive pulmonary disease.[2] Outside of the traditional medical context, it is gaining in popularity as a nootropic substance that produces mild-to-moderate stimulant effects.

This compound was initially patented in 1960 and licensed for use in 1968.[3] It is on the World Health Organization's List of Essential Medicines needed in a basic health system.[4] It is available as a generic medication and is available over the counter in many countries.[5]

N-Acetylcysteine (NAC) is emerging as a useful agent in the treatment of psychiatric disorders.[6] It is currently being explored in its effect and relief of a wide variety of cognitive disorders including, but not limited to addiction, autism, compulsive and grooming disorders, schizophrenia, bipolar disorder, and the effects of psychedelic use.[7] N-acetylcysteine has shown promising results in populations with these disorders and others whom treatment efficacy has previously been limited.

The recommended safe oral dosage range of N-acetylcysteine ranges between 300mg and 3000mg.


N-Acetylcysteine, or (2R)-2-acetamido-3-sulfanylpropanoic acid, is similar to both L-Cysteine (NAC being but an acetylated form of it) and the glutathione enzyme itself (being the direct precursor to glutathione synthesis). The structure of N-Acetylcysteine is comprised of propanoic acid, a three carbon chain with a carboxyl group (C(=O)OH) on the terminal carbon. This chain is substituted at R3 with a sulfanyl group, and at R2 with an acetamide (CH3CONH2) constituent in dextrorotary conformation. It is structurally related to cysteine, with an additional acetyl group at RN.


Acetylcysteine serves as a prodrug to L-cysteine. L-cysteine is a precursor to the biologic antioxidant glutathione; thus, administration of acetylcysteine replenishes glutathione stores.[8] This is why N-acetylcysteine is used in the event of a paracetamol overdose. It works by increasing glutathione levels and binding with the toxic breakdown products of paracetamol.[9]

In terms of its psychologically beneficial effects, N-acetylcysteine targets glutaminergic and dopaminergic pathways.[10] This could potentially account for its stimulating properties. It is also thought that provision of additional cysteine (an endogenous amino acid) via N-acetylcysteine supplementation reverses function disturbed with usage of drugs in the pathology of addiction.[11]

Subjective effects

Disclaimer: The effects listed below cite the Subjective Effect Index (SEI), a research literature based on collected anecdotal reports and the personal experiences of PsychonautWiki contributors. As a result, they should be regarded with a healthy degree of skepticism. It is worth noting that these effects will not necessarily occur in a predictable or reliable manner, although higher doses are more liable to induce a full spectrum of effects. Likewise, adverse effects become much more likely with higher doses and may include addiction, serious injury, or death ☠.

In comparison to other commonly used nootropics, N-acetylcysteine has considerably stronger stimulation and motivation enhancement, but with a greater amount of side effects such as dehydration and nausea. However, unlike other stimulants, this compound does not seem to induce a "crash" or "come down" during the offset of its experience.

Physical effects

Cognitive effects

Toxicity and harm potential

N-Acetylcysteine is considered to be safe for most adults when used as a prescription medication although the exact toxic dosage is unknown. However, dosage ranges more than twenty grams over an extended period may adversely affect heart and lung function.[18]

This compound can also rarely cause rashes, fever, headache, drowsiness, nose bleeds, low blood pressure, and liver problems.[19]

It is strongly recommended that one use harm reduction practices when using this drug.

Tolerance and addiction potential

The chronic use of N-Acetylcysteine does not seem to cause addiction or psychological dependence. This is likely a result of its known mechanisms for reversing drug addiction.[20]

Tolerance to many of the effects of N-Acetylcysteine develops quickly with repeated use. This results in users having to administer increasingly large doses to achieve the same effects. After that, it takes about 3 - 7 days for the tolerance to be reduced to half and 1 - 2 weeks to be back at baseline (in the absence of further consumption). N-Acetylcysteine does not seem to present a cross-tolerance with other stimulants.

Legal status

N-Acetylcysteine is uncontrolled in most countries, and is legally bought and sold in pharmacies and supplement stores without a prescription.

See also

External links


  1. Olsson, B.; Johansson, M.; Gabrielsson, J.; Bolme, P. (1988). "Pharmacokinetics and bioavailability of reduced and oxidized N-acetylcysteine". European Journal of Clinical Pharmacology. 34 (1): 77–82. doi:10.1007/BF01061422. ISSN 0031-6970. 
  2. Acetylcysteine | http://www.drugs.com/monograph/acetylcysteine.html
  3. Analogue-based Drug Discovery edited by IUPAC, Janos Fischer, C. Robin Ganellin | https://books.google.ca/books?id=FjKfqkaKkAAC&pg=PA544#v=onepage&q&f=false
  4. WHO Model List of Essential Medicines | http://apps.who.int/iris/bitstream/10665/93142/1/EML_18_eng.pdf?ua=1
  5. The Top 100 Drugs e-book: Clinical Pharmacology and Practical Prescribing By Andrew Hitchings, Dagan Lonsdale, Daniel Burrage, Emma Baker | https://books.google.ca/books?id=oeYjAwAAQBAJ&pg=PT44#v=onepage&q&f=false
  6. N-acetylcysteine in psychiatry: current therapeutic evidence and potential mechanisms of action | http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3044191/
  7. N-acetylcysteine modulates hallucinogenic 5-HT(2A) receptor agonist-mediated responses: behavioral, molecular, and electrophysiological studies.| https://www.ncbi.nlm.nih.gov/pubmed/24534112
  8. ACETADOTE® CONCENTRATED INJECTION Product Information | https://www.ebs.tga.gov.au/ebs/picmi/picmirepository.nsf/pdf?OpenAgent&id=CP-2010-PI-03960-3&d=2016041216114622483
  9. Acetylcysteine (Drugs.com) | http://www.drugs.com/monograph/acetylcysteine.html
  10. N-acetylcysteine in psychiatry: current therapeutic evidence and potential mechanisms of action (PubMed.gov / NCBI) | https://www.ncbi.nlm.nih.gov/pubmed/21118657
  11. Cystine/glutamate exchange regulates metabotropic glutamate receptor presynaptic inhibition of excitatory transmission and vulnerability to cocaine seeking (PubMed.gov / NCBI) | http://www.ncbi.nlm.nih.gov/pubmed/16000629
  12. Review: could Acetylcysteine cause Bleeding from the nose? | http://www.ehealthme.com/ds/acetylcysteine/bleeding+from+the+nose
  13. Cystine/glutamate exchange regulates metabotropic glutamate receptor presynaptic inhibition of excitatory transmission and vulnerability to cocaine seeking (PubMed.gov / NCBI) | http://www.ncbi.nlm.nih.gov/pubmed/16000629
  14. The Role of Cystine-Glutamate Exchange in Nicotine Dependence in Rats and Humans (PubMed.gov / NCBI) | http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2756612/
  15. Safety and Tolerability of N-Acetylcysteine in Cocaine-Dependent Individuals (PubMed.gov / NCBI) | http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1513138/
  16. N-acetylcysteine (NAC) in young marijuana users: an open-label pilot study (PubMed.gov / NCBI) | http://www.ncbi.nlm.nih.gov/pubmed/20163391/
  17. Glutamate transmission in addiction (PubMed.gov / NCBI) | http://www.ncbi.nlm.nih.gov/pubmed/18675832/
  18. S-Nitrosothiols signal hypoxia-mimetic vascular pathology | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1952618/
  19. Acetylcysteine | http://www.drugs.com/monograph/acetylcysteine.html
  20. Cystine/glutamate exchange regulates metabotropic glutamate receptor presynaptic inhibition of excitatory transmission and vulnerability to cocaine seeking (PubMed.gov / NCBI) | http://www.ncbi.nlm.nih.gov/pubmed/16000629