Phentermine and Topiramate Side Effects

Common Side Effects

Phentermine and topiramate has been studied thoroughly in clinical trials. In these studies, one group of people received the real medication, while another group was given a placebo (a "sugar pill" with no active ingredients). As a result, it was possible to see what side effects occurred, how often they appeared, and how they compared to the placebo.
In clinical studies, the most common phentermine and topiramate side effects included:
  • Unusual sensations, such as tingling, numbness, or pricking, especially of the hands, feet, or face -- in up to 19.9 percent of people
  • Dry mouth -- up to 19.1 percent
  • Constipation -- up to 16.1 percent
  • Upper respiratory tract infection -- up to 15.8 percent
  • The common cold -- up to 12.5 percent
  • Headache -- up to 10.6 percent
  • Changes in how things taste -- up to 9.4 percent
  • Insomnia -- up to 9.4 percent
  • Dizziness -- up to 8.6 percent.
  • Inflammation or infection of the sinuses -- up to 7.8 percent.
Other common side effects, occurring in 2 percent to 7.5 percent of people, included:
Last reviewed by: Kristi Monson, PharmD
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