Drug interactions
Efavirenz + Tolterodine
Severity: Minor
Efavirenz and Tolterodine: 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
Efavirenz induces CYP3A4 and may lower tolterodine concentrations. In most patients CYP2D6 is the main clearance route, so the effect is probably small, but it could matter in poor CYP2D6 metabolisers. Reduced bladder control could result if exposure falls.
What this interaction means in plain words
Efavirenz and Tolterodine 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; Tolterodine belongs to Genitourinary.
Why it happens
Efavirenz induces CYP3A4, increasing tolterodine metabolism.
What to do
No routine dose change is needed. Review symptom control and increase the tolterodine dose only if the response is inadequate.
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 Tolterodine
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 Tolterodine?
MediHelp rates the interaction as minor. Efavirenz and Tolterodine 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 induces CYP3A4 and may lower tolterodine concentrations. In most patients CYP2D6 is the main clearance route, so the effect is probably small, but it could matter in poor CYP2D6 metabolisers. Reduced bladder control could result if exposure falls.
How serious is the interaction between Efavirenz and Tolterodine?
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 routine dose change is needed. Review symptom control and increase the tolterodine dose only if the response is inadequate.
What other medicines interact with Tolterodine?
MediHelp also lists interactions of Tolterodine with, for example, Clarithromycin, Clozapine, Cobicistat. The full list is on the Tolterodine page.
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