Drug interactions
Efavirenz + Proguanil
Severity: Moderate
Efavirenz and Proguanil: 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 may lower concentrations of cycloguanil, the active metabolite of proguanil, and has been associated with reduced exposure to atovaquone-proguanil. This could reduce malaria prophylaxis or treatment efficacy.
What this interaction means in plain words
Efavirenz and Proguanil 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; Proguanil belongs to Anti Parasitic.
Why it happens
Probable induction of CYP-mediated metabolism by efavirenz, reducing proguanil and cycloguanil exposure; the exact mechanism is not firmly established.
What to do
Consider other malaria prophylaxis options and reinforce bite-prevention measures. If used, monitor for breakthrough infection.
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 Efavirenz with Proguanil?
MediHelp rates the interaction as moderate. Efavirenz and Proguanil 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 may lower concentrations of cycloguanil, the active metabolite of proguanil, and has been associated with reduced exposure to atovaquone-proguanil. This could reduce malaria prophylaxis or treatment efficacy.
How serious is the interaction between Efavirenz and Proguanil?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Consider other malaria prophylaxis options and reinforce bite-prevention measures. If used, monitor for breakthrough infection.
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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