Drug interactions
Butalbital + Efavirenz
Severity: Moderate
Butalbital and Efavirenz: 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
Butalbital is a barbiturate and may induce metabolism of efavirenz, lowering its levels. Occasional use likely has limited impact, but regular use could reduce antiviral efficacy.
What this interaction means in plain words
Butalbital and Efavirenz 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.
Why it happens
Enzyme induction (CYP3A4/CYP2B6) by butalbital increases efavirenz clearance.
What to do
Avoid frequent butalbital use and monitor viral load if used regularly.
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
Frequently asked questions
Can I take Butalbital with Efavirenz?
MediHelp rates the interaction as moderate. Butalbital and Efavirenz 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. Butalbital is a barbiturate and may induce metabolism of efavirenz, lowering its levels. Occasional use likely has limited impact, but regular use could reduce antiviral efficacy.
How serious is the interaction between Butalbital and Efavirenz?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid frequent butalbital use and monitor viral load if used regularly.
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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