Acetazolamide and Phentermine and topiramate interaction
Acetazolamide and Phentermine and topiramate: 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 Phentermine and topiramate label · effective 2026-05-18
Avoid use of phentermine and topiramate extended-release capsules with other carbonic anhydrase inhibitors.
If concomitant use of phentermine and topiramate extended-release capsules with another carbonic anhydrase inhibitor is unavoidable, the patient should be monitored for the appearance or worsening of metabolic acidosis.
Concomitant use of phentermine and topiramate extended-release capsules and a carbonic anhydrase inhibitor may increase the severity of metabolic acidosis and may also increase the risk of kidney stone formation [see Warnings and Precautions (5.10) ] .
In addition, when phentermine and topiramate extended-release capsules are used in conjunction with nonpotassium sparing diuretics this may further potentiate potassium-wasting.
…phentermine and topiramate extended-release capsules dosage reduction or discontinuation if cognitive dysfunction persists [see Warnings and Precautions (5.5) ] Non-Potassium Sparing Diuretics Clinical Impact Concurrent use of phentermine and topiramate extended-release capsules with non-potassium sparing diuretics may potentiate the potassium-wasting action of…
From the Acetazolamide label · effective 2026-01-23
By decreasing the gastrointestinal absorption of primidone, acetazolamide may decrease serum concentrations of primidone and its metabolites, with a consequent possible decrease in anticonvulsant effect.
Acetazolamide decreases urinary excretion of amphetamine and may enhance the magnitude and duration of their effect.
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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.