Weight Loss & Metabolic Health
What Is Qsymia?
Last reviewed: May 2026 · Haute MD Editorial Team
Qsymia is an oral, once-daily combination of phentermine (an appetite suppressant) and topiramate (an anticonvulsant that increases satiety and reduces cravings), FDA-approved for chronic weight management in adults with BMI ≥30, or ≥27 with comorbidities. It produces average weight loss of 9–11% over 56 weeks — more than phentermine alone and at lower doses of each component than full-dose monotherapy.
How Qsymia works
Phentermine suppresses appetite via norepinephrine release in the hypothalamus, while topiramate reduces appetite, increases satiety, and dampens reward-driven eating through GABA, glutamate, and carbonic anhydrase pathways. The combination produces greater weight loss than either component alone while allowing lower doses of each, reducing some side effects. Qsymia is available in four strengths (3.75/23 mg through 15/92 mg) and titrated over 4–14 weeks.
Clinical results
In the CONQUER and EQUIP trials, patients on full-dose Qsymia lost approximately 9.8% of body weight at 56 weeks versus 1.6% on placebo, with about 70% of patients losing at least 5% of body weight. Weight loss is comparable to liraglutide and less than semaglutide or tirzepatide, but Qsymia is oral and substantially cheaper. It is FDA-approved for chronic (long-term) use, unlike phentermine monotherapy.
Side effects and important cautions
Common side effects include paresthesias (tingling in hands and feet), dry mouth, constipation, taste changes (particularly with carbonated drinks), insomnia, and cognitive effects ('brain fog'). Topiramate carries a meaningful risk of birth defects, so Qsymia requires effective contraception and pregnancy testing in women of reproductive age, and is contraindicated in pregnancy. It is also contraindicated in glaucoma, hyperthyroidism, recent MAO inhibitor use, and severe cardiovascular disease. Kidney stones are a known risk.
Frequently Asked Questions
Is Qsymia better than phentermine alone?
Average weight loss is greater (9–11% vs 5–8%) and it's FDA-approved for chronic use rather than short-term only.
How does Qsymia compare to GLP-1 medications?
Less weight loss than semaglutide or tirzepatide but oral, cheaper, and an option for patients who cannot or do not want to inject.
Can men take Qsymia?
Yes — the birth-defect risk affects only women of reproductive potential, who must use effective contraception.
Why am I getting tingling in my hands?
Paresthesia is the most common side effect, due to topiramate's effect on carbonic anhydrase. Often improves with potassium-rich foods or dose reduction.
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