Propecia with antibiotics: interactions and safety

Antibiotic courses are common, short-term and often combined with chronic medications such as Propecia (Finasteride). Most antibiotics do not interfere meaningfully with Finasteride at 1mg, but a few classes do, and a small number of combinations are best avoided.

Common antibiotic interactions

Macrolides (clarithromycin, erythromycin) and certain antifungals can inhibit hepatic metabolism (CYP3A4) and raise plasma levels of many medications including some Male and Female Pattern Hair Loss agents. Rifampicin has the opposite effect, accelerating metabolism. Most penicillins, cephalosporins, fluoroquinolones and tetracyclines have no clinically meaningful interaction with Finasteride at 1mg.

Practical guidance

According to the prescribing information for Finasteride, an antibiotic course should be reviewed by the prescriber or pharmacist for known interactions before Propecia is co-administered. Adjusted 1mg dosing or temporary substitution is sometimes preferred for the duration of the antibiotic course.

Frequently asked questions

Can I take Propecia during an antibiotic course? ▾

For most common antibiotics, yes. A few classes — notably macrolides and azole antifungals — alter how Finasteride is metabolised and may need a temporary 1mg adjustment. The prescribing pharmacist should review any new antibiotic against the existing Propecia regimen.

Will antibiotics make Propecia stop working? ▾

Most antibiotics do not affect Propecia efficacy. Rifampicin and a few others can lower Finasteride levels and reduce effect; in those cases the prescriber may adjust the dose during and shortly after the antibiotic course.

More on Propecia

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