Phentermine and topiramate and Pioglitazone and metformin interaction
Phentermine and topiramate and Pioglitazone and metformin: both prescribing labels flag this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.
What the FDA labels say
From the Pioglitazone and metformin (Actoplus Met) label · effective 2026-08-21
Risk factors for metformin-associated lactic acidosis include renal impairment, concomitant use of certain drugs (e.g., carbonic anhydrase inhibitors such as topiramate), age 65 years old or greater, having a radiological study with contrast, surgery and other procedures, hypoxic states (e.g., acute congestive heart failure), excessive alcohol intake, hepatic…
Topiramate may decrease pioglitazone concentrations.
Carbonic Anhydrase Inhibitors Topiramate or other carbonic anhydrase inhibitors (e.g., zonisamide, acetazolamide or dichlorphenamide) frequently causes a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis.
Topiramate A decrease in the exposure of pioglitazone and its active metabolites were noted with concomitant administration of pioglitazone and topiramate [see Clinical Pharmacology (12.3) ] .
The clinical relevance of this decrease is unknown; however, when ACTOPLUS MET and topiramate are used concomitantly, monitor patients for adequate glycemic control.
From the Phentermine and topiramate label · effective 2026-05-18
Pioglitazone Clinical Impact A decrease in the exposure of pioglitazone and its active metabolites were noted with the concurrent use of pioglitazone and topiramate in a clinical trial.
Intervention Consider increased glycemic monitoring when using pioglitazone and phentermine and topiramate extended-release capsules concomitantly [see Clinical Pharmacology (12.3) ] .
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Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.