Drug interactions
Efavirenz + Formoterol
Severity: Moderate
Efavirenz and Formoterol: 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
Both drugs can prolong the QT interval, so using them together may add to the risk of ventricular arrhythmia including torsades de pointes. The risk is higher with electrolyte disturbance, structural heart disease or other QT-prolonging drugs.
What this interaction means in plain words
Efavirenz and Formoterol 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; Formoterol belongs to Respiratory.
Why it happens
Additive pharmacodynamic QT prolongation, with formoterol also lowering potassium through beta-2 stimulation.
What to do
Check baseline ECG and correct potassium and magnesium if the patient has other risk factors for QT prolongation. Monitor for palpitations or syncope.
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 Formoterol
- Adagrasib + Formoterol Major
- Amiodarone + Formoterol Major
- Amisulpride + Formoterol Major
- Amitriptyline + Formoterol Major
- Amoxapine + Formoterol Major
- Arformoterol + Formoterol Major
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 Formoterol?
MediHelp rates the interaction as moderate. Efavirenz and Formoterol 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. Both drugs can prolong the QT interval, so using them together may add to the risk of ventricular arrhythmia including torsades de pointes. The risk is higher with electrolyte disturbance, structural heart disease or other QT-prolonging drugs.
How serious is the interaction between Efavirenz and Formoterol?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Check baseline ECG and correct potassium and magnesium if the patient has other risk factors for QT prolongation. Monitor for palpitations or syncope.
What other medicines interact with Formoterol?
MediHelp also lists interactions of Formoterol with, for example, Adagrasib, Amiodarone, Amisulpride. The full list is on the Formoterol page.
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