What are phentermine and topiramate?

Qsymia contains the drugs phentermine and topiramate in extended release form. Phentermine is generally used for short-term weight loss in overweight or obese adults, in addition to exercise and a healthy diet. Because it contains phentermine, Qsymia is a federally controlled substance (CIV) and can be abused or lead to drug dependence. Topiramate, the generic version of Topamax, is used to treat certain types of epileptic seizures and to prevent migraine headaches.

Anti-epileptic drugs (AEDs) such as topiramate pose concerns about possible teratogenicity, an agent that causes malformation of a fetus. Topiramate has been associated with severe eye problems such as sudden decrease in vision and glaucoma. These side effects can lead to permanent vision loss. The drug also increases the risk of suicidal thoughts.

A fetus exposed to topiramate in the first trimester of pregnancy has an increased risk of a cleft lip and/or cleft palate. Women of childbearing years must not be pregnant or become pregnant when taking Qsymia. Women should have a negative pregnancy test before starting Qsymia and every month while taking the drug, and they should consistently use effective contraception during this time.