Drug interactions
Efavirenz + Rifabutin
Severity: Moderate
Efavirenz and Rifabutin: moderate interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Efavirenz lowers rifabutin concentrations through enzyme induction, which may reduce its efficacy against mycobacterial infection. Rifabutin dosing therefore needs to be increased when it is used with efavirenz.
What this interaction means in plain words
Efavirenz and Rifabutin can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Efavirenz belongs to Anti Virals; Rifabutin belongs to Anti Bacterial.
Why it happens
Efavirenz induces CYP3A4, increasing the clearance of rifabutin.
What to do
Increase the rifabutin daily dose as recommended in product labeling when combined with efavirenz. Monitor for clinical response and rifabutin-related toxicity such as uveitis and neutropenia.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Efavirenz
- Cobimetinib + Efavirenz Contraindicated
- Dienogest / estradiol valerate + Efavirenz Contraindicated
- Dihydroergotamine intranasal + Efavirenz Contraindicated
- Dihydroergotamine + Efavirenz Contraindicated
- Doravirine + Efavirenz Contraindicated
- Efavirenz + Elbasvir / grazoprevir Contraindicated
Other interactions of Rifabutin
- Cabotegravir + Rifabutin Contraindicated
- Lorlatinib + Rifabutin Contraindicated
- Rifabutin + Voriconazole Contraindicated
- Apixaban + Rifabutin Major
- Axitinib + Rifabutin Major
- Brexpiprazole + Rifabutin Major
Frequently asked questions
Can I take Efavirenz with Rifabutin?
MediHelp rates the interaction as moderate. Efavirenz and Rifabutin can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Efavirenz lowers rifabutin concentrations through enzyme induction, which may reduce its efficacy against mycobacterial infection. Rifabutin dosing therefore needs to be increased when it is used with efavirenz.
How serious is the interaction between Efavirenz and Rifabutin?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Increase the rifabutin daily dose as recommended in product labeling when combined with efavirenz. Monitor for clinical response and rifabutin-related toxicity such as uveitis and neutropenia.
What other medicines interact with Efavirenz?
MediHelp also lists interactions of Efavirenz with, for example, Cobimetinib, Dienogest / estradiol valerate, Dihydroergotamine intranasal. The full list is on the Efavirenz page.
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