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Summary sheet: Efavirenz
Chemical Nomenclature
Common names Efavirenz, Sustiva
Systematic name (4S)-6-chloro-4-(2-cyclopropylethynyl)-4-(trifluoromethyl)-2,4-dihydro-1H-3,1-benzoxazin-2-one
Class Membership
Psychoactive class Psychedelic
Chemical class Benzoxazine
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 50%[1]
Common 600 - 1800 mg
Onset 1 - 5 minutes
Peak 1 - 2 hours
After effects 6 - 12 hours

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.

Serotonin releasers

Efavirenz (sold by the brand name Sustiva) is an antiretroviral medication used in the treatment and prevention of HIV/AIDS.[2] It is notable for being able to produce psychedelic and hallucinogenic effects despite possessing an extremely novel pharmacological profile and chemical structure not shared with any other psychedelic substance.

Efavirenz was approved for medical use in the United States in 1998.[citation needed] It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system.[3]

Recreational use of efavirenz for its hallucinogenic and dissociative effects has been reported in South Africa. The tablets are reportedly crushed and smoked in a mixture known as "whoonga" , "nyaope" , and "wonga". A form of black tar heroin. Although current analyses of whoonga samples have yet to confirm the presence efavirenz in the mixture. [4][5][6]


Unlike most psychedelics, efavirenz is not a tryptamine, phenethylamine or lysergamide. Efavirenz is classified as a benzoxazine and has several different moieties which give it a unique pharmacological profile. On the two position of the benzoxazine ring, efavirenz has a ketone attached. Efavirenz also has a trifluoromethyl group as well as a cyclopropane ring.

Efavirenz is a white to slightly pink crystalline powder with a molecular mass of 315.68 g/mol. It is practically insoluble in water (<10 µg/mL).. Efavirenz is chemically described as (S)-6-chloro-(cyclopropylethynyl)-1,4-dihydro-4-(trifluoromethyl)-2H-3,1-benzoxazin-2-one. Its empirical formula is C14H9ClF3NO2.


Pharmacologically, efavirenz is primarily classified as a non-nucleotide reverse transcriptase inhibitor, or NNRTI. Reverse transcriptase is an enzyme found in several viral species that is a type of DNA polymerase and nuclease that allows viruses like hepatitis and human immunodeficiency virus to transcribe viral RNA into DNA. Efavirenz is considered a non-nucleotide reverse transcriptase inhibitor because it does not have a structure based off of a nucleotide.

Unlike most non-nucleotide reverse transcriptase inhibitors, efavirenz is also a 5-HT2A partial agonist, similar to LSD. Additionally, efavirenz is a serotonin and dopamine reuptake inhibitor and a vesicular monoamine transporter 2 inhibitor. Efavirenz also acts as a GABAA positive allosteric modulator, similar to benzodiazepines and barbiturates.[7] Efavirenz has a bioavailability of about 40-45% when it is taken on an empty stomach.

Efavirenz is known to cause a false-positive for cannabis on some urine tests.[8]

Subjective effects

Disclaimer: The effects listed below cite the Subjective Effect Index (SEI), an open research literature based on anecdotal user reports and the personal analyses of PsychonautWiki contributors. As a result, they should be viewed with a healthy degree of skepticism.

It is also worth noting that these effects will not necessarily occur in a predictable or reliable manner, although higher doses are more liable to induce the full spectrum of effects. Likewise, adverse effects become increasingly likely with higher doses and may include addiction, severe injury, or death ☠.

Cognitive effects

Toxicity and harm potential

Efavirenz has a low toxicity relative to dose. Like many HIV medications, efavirenz may cause liver toxicity at high doses or after chronic use.

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

Tolerance and addiction potential

Efavirenz is not known to be habit-forming. While developing a tolerance to efavirenz is extremely rare, abusing efavirenz may cause HIV to become resistant to the drug and increase the viral load in patients with HIV.

Dangerous interactions

As efavirenz may cause hepatoxicity at high doses or after chronic use, it is not recommended to take this substance concurrently with other substances that may cause hepatoxicity. Efavirenz is an inducer of the CYP2B6 and CYP3A4 enzymes of the cytochrome P450 system, and as a result may change the metabolism of drugs metabolized by them. Consuming garlic may decrease serum levels of efavirenz.

Serotonin syndrome risk

Efavirenz is a weak serotonin reuptake inhibitor, so it is possible that combining heavy doses of efavirenz and the substances listed below may result in serotonin syndrome. Combinations with the following substances can cause dangerously high serotonin levels. Serotonin syndrome requires immediate medical attention and can be fatal if left untreated.

Legal status


This legality section is a stub.

As such, it may contain incomplete or wrong information. You can help by expanding it.

Efavirenz is not known to be illegal in any jurisdictions, and is considered a prescription only medication.

  • Germany: Efavirenz is a prescription only medicine, according to Anlage 1 AMVV.[10]
  • Switzerland: Efavirenz is listed as a "Abgabekategorie A" pharmaceutical, which requires a prescription.[citation needed]

See also

External links


  1. Apostolova, N., Funes, H. A., Blas-Garcia, A., Galindo, M. J., Alvarez, A., Esplugues, J. V. (October 2015). "Efavirenz and the CNS: what we already know and questions that need to be answered". The Journal of Antimicrobial Chemotherapy. 70 (10): 2693–2708. doi:10.1093/jac/dkv183. ISSN 1460-2091. 
  2. New item… Vrouenraets, S. M., Wit, F. W., Tongeren, J. van, Lange, J. M. (April 2007). "Efavirenz: a review". Expert Opinion on Pharmacotherapy. 8 (6): 851–871. doi:10.1517/14656566.8.6.851. ISSN 1465-6566. 
  3. "WHO Model List of Essential Medicines (19th List)" (PDF). World Health Organization. April 2015. Archived (PDF) from the original on 13 December 2016. Retrieved 8 December 2016. 
  4. Getting high on HIV drugs in S Africa, 2008 
  5. News, A. B. C., “No Turning Back”: Teens Abuse HIV Drugs 
  6. Vice (2014), Getting High On HIV Medication - Part 1/2 
  7. Gatch, M. B., Kozlenkov, A., Huang, R.-Q., Yang, W., Nguyen, J. D., González-Maeso, J., Rice, K. C., France, C. P., Dillon, G. H., Forster, M. J., Schetz, J. A. (November 2013). "The HIV Antiretroviral Drug Efavirenz has LSD-Like Properties". Neuropsychopharmacology. 38 (12): 2373–2384. doi:10.1038/npp.2013.135. ISSN 1740-634X. 
  8. Rossi, S., Yaksh, T., Bentley, H., Brande, G. van den, Grant, I., Ellis, R. (1 May 2006). "Characterization of Interference with 6 Commercial Δ9-Tetrahydrocannabinol Immunoassays by Efavirenz (Glucuronide) in Urine". Clinical Chemistry. 52 (5): 896–897. doi:10.1373/clinchem.2006.067058. ISSN 0009-9147. 
  9. Gillman, P. K. (2005). "Monoamine oxidase inhibitors, opioid analgesics and serotonin toxicity". British Journal of Anaesthesia. 95 (4): 434–441. doi:10.1093/bja/aei210Freely accessible. eISSN 1471-6771. ISSN 0007-0912. OCLC 01537271. PMID 16051647. 
  10. "Anlage 1 AMVV" (in German). Bundesministerium der Justiz und für Verbraucherschutz. Retrieved December 11, 2019.