Glucophage with antibiotics: interactions and safety

Antibiotic courses are common, short-term and often combined with chronic medications such as Glucophage (Metformin). Most antibiotics do not interfere meaningfully with Metformin at 500mg, 850mg, 1000mg, 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 Diabetes Treatment agents. Rifampicin has the opposite effect, accelerating metabolism. Most penicillins, cephalosporins, fluoroquinolones and tetracyclines have no clinically meaningful interaction with Metformin at 500mg, 850mg, 1000mg.

Practical guidance

According to the prescribing information for Metformin, an antibiotic course should be reviewed by the prescriber or pharmacist for known interactions before Glucophage is co-administered. Adjusted 500mg, 850mg, 1000mg dosing or temporary substitution is sometimes preferred for the duration of the antibiotic course.

Frequently asked questions

Can I take Glucophage during an antibiotic course? ▾

For most common antibiotics, yes. A few classes — notably macrolides and azole antifungals — alter how Metformin is metabolised and may need a temporary 500mg, 850mg, 1000mg adjustment. The prescribing pharmacist should review any new antibiotic against the existing Glucophage regimen.

Will antibiotics make Glucophage stop working? ▾

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

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