Drug interactions
Chlorpheniramine + Efavirenz
Severity: Minor
Chlorpheniramine and Efavirenz: 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
Chlorpheniramine is partly metabolised by CYP3A4, so efavirenz may lower its levels modestly. Both drugs can cause drowsiness, so sedation may add up.
What this interaction means in plain words
Chlorpheniramine and Efavirenz have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Chlorpheniramine belongs to Respiratory; Efavirenz belongs to Anti Virals.
Why it happens
CYP3A4 induction by efavirenz and additive CNS depression.
What to do
Counsel on drowsiness and driving; adjust the antihistamine if efficacy is reduced.
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 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 Chlorpheniramine
Frequently asked questions
Can I take Chlorpheniramine with Efavirenz?
MediHelp rates the interaction as minor. Chlorpheniramine and Efavirenz have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Chlorpheniramine is partly metabolised by CYP3A4, so efavirenz may lower its levels modestly. Both drugs can cause drowsiness, so sedation may add up.
How serious is the interaction between Chlorpheniramine and Efavirenz?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Counsel on drowsiness and driving; adjust the antihistamine if efficacy is reduced.
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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