Acyclovir with antibiotics: interactions and safety

Antibiotic courses are common, short-term and often combined with chronic medications such as Acyclovir (Acyclovir). Most antibiotics do not interfere meaningfully with Acyclovir at 200mg, 400mg, 800mg, 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 Antiviral Medications agents. Rifampicin has the opposite effect, accelerating metabolism. Most penicillins, cephalosporins, fluoroquinolones and tetracyclines have no clinically meaningful interaction with Acyclovir at 200mg, 400mg, 800mg.

Practical guidance

According to the prescribing information for Acyclovir, an antibiotic course should be reviewed by the prescriber or pharmacist for known interactions before Acyclovir is co-administered. Adjusted 200mg, 400mg, 800mg dosing or temporary substitution is sometimes preferred for the duration of the antibiotic course.

Frequently asked questions

Can I take Acyclovir during an antibiotic course? ▾

For most common antibiotics, yes. A few classes — notably macrolides and azole antifungals — alter how Acyclovir is metabolised and may need a temporary 200mg, 400mg, 800mg adjustment. The prescribing pharmacist should review any new antibiotic against the existing Acyclovir regimen.

Will antibiotics make Acyclovir stop working? ▾

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

More on Acyclovir

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