Drug interactions
Efavirenz + Zafirlukast
Severity: Minor
Efavirenz and Zafirlukast: minor 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
Zafirlukast may slightly raise efavirenz exposure, though efavirenz is also an enzyme inducer that could lower zafirlukast levels. Net clinical effect is uncertain; CNS effects of efavirenz could be slightly increased.
What this interaction means in plain words
Efavirenz and Zafirlukast have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Efavirenz belongs to Anti Virals; Zafirlukast belongs to Respiratory.
Why it happens
Weak CYP3A4 inhibition by zafirlukast may reduce efavirenz metabolism, while efavirenz induction may lower zafirlukast.
What to do
No empirical adjustment; monitor for CNS adverse effects and for reduced asthma control.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Zafirlukast
- Pimozide + Zafirlukast Contraindicated
- Lomitapide + Zafirlukast Major
- Nilotinib + Zafirlukast Major
- Warfarin + Zafirlukast Major
- Apalutamide + Zafirlukast Moderate
- Carbamazepine + Zafirlukast Moderate
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 Zafirlukast?
MediHelp rates the interaction as minor. Efavirenz and Zafirlukast have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Zafirlukast may slightly raise efavirenz exposure, though efavirenz is also an enzyme inducer that could lower zafirlukast levels. Net clinical effect is uncertain; CNS effects of efavirenz could be slightly increased.
How serious is the interaction between Efavirenz and Zafirlukast?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: No empirical adjustment; monitor for CNS adverse effects and for reduced asthma control.
What other medicines interact with Zafirlukast?
MediHelp also lists interactions of Zafirlukast with, for example, Pimozide, Lomitapide, Nilotinib. The full list is on the Zafirlukast page.
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