Drug interactions
Efavirenz + Guanfacine
Severity: Moderate
Efavirenz and Guanfacine: 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 induces CYP3A4 and lowers guanfacine concentrations. This can reduce blood pressure control or ADHD symptom control.
What this interaction means in plain words
Efavirenz and Guanfacine 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; Guanfacine belongs to Cardiovascular.
Why it happens
CYP3A4 induction by efavirenz accelerates guanfacine metabolism.
What to do
Monitor blood pressure and clinical response and consider raising the guanfacine dose, with extended-release labeling suggesting doubling. Reduce the dose again if efavirenz is stopped.
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 Guanfacine
- Clonidine + Guanfacine Major
- Guanfacine + Lofexidine Major
- Aldesleukin + Guanfacine Moderate
- Amiodarone + Guanfacine Moderate
- Amisulpride + Guanfacine Moderate
- Amitriptyline + Guanfacine Moderate
Frequently asked questions
Can I take Efavirenz with Guanfacine?
MediHelp rates the interaction as moderate. Efavirenz and Guanfacine 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 induces CYP3A4 and lowers guanfacine concentrations. This can reduce blood pressure control or ADHD symptom control.
How serious is the interaction between Efavirenz and Guanfacine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor blood pressure and clinical response and consider raising the guanfacine dose, with extended-release labeling suggesting doubling. Reduce the dose again if efavirenz is stopped.
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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