Efavirenz

For an informed discussion with your doctor or pharmacist. This information collection is not a clinically validated interaction checker. Missing data do not establish safety. Do not change or stop prescribed medicines on the basis of this information. The findings apply to the specific conditions studied; laboratory and animal studies cannot be directly extrapolated to humans.

Active substance: Efavirenz

Examples of brand names: Sustiva [EU]

ATC code: J05AG03

Main use (for orientation): HIV

Documented research summary

The THC plus efavirenz combination in rats alters reward/neurochemical signals; a small retrospective cohort with mixed substance use found no significant CNS difference. Neither clinical proof of safety nor a quantitatively determined cannabis pharmacokinetic interaction.

Uncertainties and limitations

SYMFI also contains lamivudine/TDF; only efavirenz passages evaluated, without equating regimens.

Shared enzymes must not be equated with clinical evidence of an interaction; CBD/THC findings cannot be extrapolated to other cannabinoids.

Separately recorded findings

2 separately recorded findings. Each statement applies to its documented study context.

Δ9-THC – laboratory and animal studies

Finding ID: B0174

Type of result: Animal experiment

Observation: THC plus efavirenz increased preference/reward signals and altered regional monoamines compared with comparator groups.

Mechanism: Central pharmacodynamic interaction in a rat model

Study type: Subchronic rat combination study

Context studied: Efavirenz 5 mg/kg; THC 0.75 mg/kg; behavioural/neurochemical endpoints.

Clinical interpretation: Preclinical signal, not a human risk estimate.

Limitations and uncertainties: No human pharmacokinetics or therapeutic efficacy assessed.

Original sources for this finding: Efavirenz exposure, alone and in combination with known drugs of abuse, engenders addictive-like bio-behavioural changes in rats. [BMED30150782]

Cannabis (not standardised; mixed recreational-drug cohort) – clinical signals

Finding ID: B0175

Type of result: Observational; low

Observation: No significant differences in CNS adverse effects/discontinuation rates between users and non-users.

Mechanism: Observation of central tolerability

Study type: Retrospective, single centre, 134 patients

Context studied: Cocaine/ecstasy/cannabis recorded together; no standardised cannabinoid dose.

Clinical interpretation: No specific evidence of CBD/THC safety.

Limitations and uncertainties: Confounding, small subgroups, no direct pharmacokinetics; absence of statistical significance does not establish equivalence.

Original sources for this finding: Recreational substance use and tolerance of efavirenz in HIV-1 infected patients. [BMED16120507]

References and access status

[V2_LABEL_D0323] SYMFI (EFAVIRENZ, LAMIVUDINE AND TENOFOVIR DISOPROXIL FUMARATE) TABLET, FILM COATED [VIATRIS SPECIALTY LLC]

Original source / bibliographic reference

Authors: Viatris Specialty LLC

Year: 2019

Source type: Official US SPL / DailyMed

Source access – 23 October 2026: Source destination was accessible when checked.

Bibliographic attribution or source identity cross-checked.

[BMED30150782] Efavirenz exposure, alone and in combination with known drugs of abuse, engenders addictive-like bio-behavioural changes in rats.

Original source / bibliographic reference

Authors: Möller M, Fourie J, Harvey BH.

Year: 2018

Source type: Publication; title and abstract reviewed

DOI: 10.1038/s41598-018-29978-3

PMID: 30150782

Source access – 23 October 2026: Automated direct retrieval was restricted; this does not establish that the link is broken.

Bibliographic attribution or source identity cross-checked.

PubMed – bibliographic reference / abstract

PubMed Central – archived text

DOI – publisher access (access restrictions may apply)

[BMED16120507] Recreational substance use and tolerance of efavirenz in HIV-1 infected patients.

Original source / bibliographic reference

Authors: Faggian F, Lattuada E, Lanzafame M, Antolini D, Concia E, Vento S.

Year: 2005

Source type: Publication; title and abstract reviewed

DOI: 10.1080/09540120500038371

PMID: 16120507

Source access – 23 October 2026: Automated direct retrieval was restricted; this does not establish that the link is broken.

Bibliographic attribution or source identity cross-checked.

PubMed – bibliographic reference / abstract

DOI – publisher access (access restrictions may apply)

Research as of 23 October 2026. Not all original full texts could be reviewed in full. Source accessibility and the strength of scientific evidence must be assessed separately. An accessible link does not establish medical approval; a bibliographic record with an abstract does not replace the original full text.

Drug search and explanation of the evidence · Guide: cannabinoids and medicines · Author and responsibility