Supplements and Efavirenz.
Efavirenz, sold under the brand name Sustiva, is classified under "nnrti" in the BNF.
Efavirenz is a non-nucleoside reverse transcriptase inhibitor (NNRTI). The class binds HIV reverse transcriptase directly and forms a backbone of combination antiretroviral therapy. Efavirenz, the most established agent, is itself a CYP3A4 inducer and a CYP2B6 substrate, which is why its own drug interactions run deep. The supplement rules follow the same logic as the protease inhibitor page. Steady antiretroviral levels are what hold the virus suppressed, so anything that shifts them risks toxicity or, more dangerously, treatment failure and resistance. St John's Wort sits on the induction side and is the textbook exclusion. Supplements that inhibit CYP3A4, including curcumin, quercetin, resveratrol, schisandra and berberine, can raise levels instead. Immune-active herbs (echinacea, andrographis, elderberry, cordyceps, astragalus) are excluded as a precaution on antiretroviral therapy regardless of CD4 count. As with all antiretroviral therapy, the HIV team signs off any new supplement rather than community pharmacy.
Below are the 2 documented pairs we have explicitly assessed against Efavirenz in the Distil database: 1 red and 1 amber. The pairs cluster around 1 mechanism: CYP induction. Every call is cited to either a clinical reference (PMID) or the British National Formulary. Anything not on this list is either still to be assessed or beyond our database scope. The checker beneath surfaces assessments by supplement, and the missing-item form at the bottom of the page routes any uncatalogued supplement into our next curation pass.
Documented interactions
Last reviewed 14 June 2026. Each interaction below is assessed against PubMed-indexed evidence.
CYP induction
Red Does St John's Wort interact with ?
St John's Wort speeds up how the body clears the HIV medicine efavirenz, which can drop the drug level too low to control the virus and let HIV become resistant. This is a serious interaction and the two should not be combined. If you take efavirenz, do not start St John's Wort, and if you already take both, tell your HIV team before changing anything.
Evidence: Supported by human study data.
Amber Does Ginkgo Biloba interact with ?
Ginkgo may lower the level of the HIV medicine efavirenz in the blood, which could let the virus rebound. This has been reported in patients who were stable for years and then lost virus control after starting ginkgo. If you take efavirenz, it is best to avoid ginkgo, or only use it with your HIV team's knowledge and viral-load monitoring.
Evidence: Limited human data, based on case reports and a known mechanism.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
What this list does not say. Pairs not flagged here are not implicitly safe. They are either not yet in our database, or fall outside our inclusion scope (food-supplement interactions only; for drug-drug interactions, the BNF is authoritative). Use the checker below to surface any supplement, and submit a missing item if you take something we have not catalogued.
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How we grade severity, choose what's in scope, and what we exclude.
Every call on this page is reasoned. We publish the full rubric for severity tiers, the medication inclusion logic, the evidence grades we accept, and what we deliberately leave out. About three thousand words. Worth reading once if you use this tool more than occasionally.
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