Rifampicin

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: Rifampicin

Examples of brand names: Eremfat [DE]

ATC code: J04AB02

Main use (for orientation): Tuberculosis; selected infections

Documented research summary

Directly established direction: rifampicin → CBD/THC. Exposure decreases with repeated inducer administration in specific human studies. Do not automatically extrapolate to rare cannabinoids or the reverse direction.

Uncertainties and limitations

US intravenous label; the cited cannabinoid studies used oral rifampicin, whose results are considered separately.

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.

CBD + Δ9-THC (nabiximols) – clinically investigated

Finding ID: B0044

Type of result: Positive finding / indication

Observation: Rifampicin reduced exposure after a single nabiximols dose. Geometric ratios, combination/alone, for THC, CBD and 11-OH-THC: Cmax 0.614/0.480/0.140; AUC0–t 0.711/0.381/0.099; AUC∞ 0.761/0.422/0.131. All associated 90% confidence intervals were below 1.

Mechanism: Enzyme induction

Study type: Randomised open-label phase I crossover pharmacokinetics

Context studied: 12 healthy men; oral rifampicin 600 mg once daily for ten days in total (nine pretreatment days plus co-administration on day ten). A single four-spray oromucosal nabiximols dose = 10.8 mg THC plus 10 mg CBD. Cmax/AUC0–t: n=12 each; AUC∞: n=11 for THC/11-OH-THC and n=10 for CBD.

Clinical interpretation: Possible attenuation of effect

Limitations and uncertainties: Direction: rifampicin → cannabinoids; not a pure CBD/THC preparation and no clinical efficacy measurement. Small group of healthy men, no formal power calculation; high variability and sometimes >20% extrapolated AUC∞.

Original sources for this finding: A Phase I, open-label, randomized, crossover study in three parallel groups to evaluate the effect of Rifampicin, Ketoconazole, and Omeprazole on the pharmacokinetics of THC/CBD oromucosal spray in healthy volunteers [CL18]

CBD – clinically studied

Finding ID: B0083

Type of result: Positive finding / indication

Observation: CBD AUC approximately −32%; 7-OH-CBD AUC approximately −63%.

Mechanism: CYP3A4/CYP2C19 induction

Study type: Phase I data in a study overview

Context studied: Pharmaceutical CBD; healthy people.

Clinical interpretation: Possible reduction in effect

Limitations and uncertainties: Direction: rifampicin → CBD.

Original sources for this finding: Clinical implications of trials investigating drug-drug interactions between cannabidiol and enzyme inducers or inhibitors or common antiseizure drugs [CL24]; EPIDIOLEX (cannabidiol) oral solution – Prescribing Information, revised 6/2025 [CL02]

References and access status

[V2_LABEL_D0303] RIFAMPIN (RIFAMPIN) INJECTION, POWDER, LYOPHILIZED, FOR SOLUTION [FRESENIUS KABI USA, LLC]

Original source / bibliographic reference

Authors: Fresenius Kabi USA, LLC

Year: 2022

Source type: Official US SPL / DailyMed

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

Bibliographic attribution or source identity cross-checked.

[CL18] A Phase I, open-label, randomized, crossover study in three parallel groups to evaluate the effect of Rifampicin, Ketoconazole, and Omeprazole on the pharmacokinetics of THC/CBD oromucosal spray in healthy volunteers

Original source / bibliographic reference

Authors: Stott C; White L; Wright S; Wilbraham D; Guy G

Year: 2013

Source type: Randomised open-label phase I crossover study

DOI: 10.1186/2193-1801-2-236

PMID: 23750331

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

Bibliographic attribution or source identity cross-checked.

PubMed – bibliographic reference / abstract

DOI – publisher access (access restrictions may apply)

[CL24] Clinical implications of trials investigating drug-drug interactions between cannabidiol and enzyme inducers or inhibitors or common antiseizure drugs

Original source / bibliographic reference

Authors: Patsalos PN; Szaflarski JP; Gidal B; VanLandingham K; Critchley D; Morrison G

Year: 2020

Source type: Study overview including manufacturer data; PubMed: review

DOI: 10.1111/epi.16674

PMID: 32918835

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)

Europe PMC – full-text access according to the literature database – Listed as freely available HTML full text in the official Europe PMC metadata. Direct retrieval was not fully verified here.

[BMED36540909] Verifying in vitro-determined enzyme contributions to cannabidiol clearance for exposure predictions in human through physiologically-based pharmacokinetic modeling.

Original source / bibliographic reference

Authors: Yeung CHT, Beers JL, Jackson KD, Edginton AN.

Year: 2023

Source type: Publication; title and abstract reviewed

DOI: 10.1002/psp4.12908

PMID: 36540909

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)

[CL02] EPIDIOLEX (cannabidiol) oral solution – Prescribing Information, revised 6/2025

Original source / bibliographic reference

Authors: FDA / Jazz Pharmaceuticals

Year: 2025

Source type: Regulatory product information

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

Bibliographic attribution or source identity cross-checked.

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