Drug interactions
Efavirenz + Orlistat
Severity: Moderate
Efavirenz and Orlistat: 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
Loss of virologic control has been reported in HIV patients taking orlistat with antiretrovirals, possibly because orlistat reduces absorption of lipophilic drugs. This could lead to subtherapeutic efavirenz levels and resistance.
What this interaction means in plain words
Efavirenz and Orlistat 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; Orlistat belongs to Miscellaneous.
Why it happens
Orlistat inhibits fat digestion, which may impair absorption of lipophilic efavirenz; the mechanism is not fully established.
What to do
Avoid orlistat in patients on efavirenz where possible. If used, monitor HIV RNA closely and stop orlistat if viral load rises.
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 Orlistat
- Cyclosporine + Orlistat Major
- Cyclosporin + Orlistat Major
- Orlistat + Triheptanoin Major
- Amiodarone + Orlistat Moderate
- Beta carotene + Orlistat Moderate
- Carbamazepine + Orlistat Moderate
Frequently asked questions
Can I take Efavirenz with Orlistat?
MediHelp rates the interaction as moderate. Efavirenz and Orlistat 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. Loss of virologic control has been reported in HIV patients taking orlistat with antiretrovirals, possibly because orlistat reduces absorption of lipophilic drugs. This could lead to subtherapeutic efavirenz levels and resistance.
How serious is the interaction between Efavirenz and Orlistat?
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 orlistat in patients on efavirenz where possible. If used, monitor HIV RNA closely and stop orlistat if viral load rises.
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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