Qsymia Guide
Qsymia is a fixed-dose oral combination of phentermine (a sympathomimetic amine appetite suppressant) and topiramate extended-release (an anticonvulsant also used for migraine prophylaxis) developed by VIVUS LLC and FDA-approved July 17, 2012 for chronic weight management. A pediatric indication for patients aged 12 years and older was added in December 2022, making Qsymia one of the few weight-loss medications approved in adolescents. It is not a GLP-1 receptor agonist — it works through central appetite suppression and modulation of GABA/glutamate signaling rather than incretin pathways. Qsymia is dispensed only through a Risk Evaluation and Mitigation Strategy (REMS) program because of teratogenicity risk (topiramate causes cleft palate in first-trimester exposures) and a suicidality warning carried over from topiramate's antiepileptic class label. Because phentermine is a Schedule IV controlled substance, prescriptions are subject to DEA limits, and Qsymia capsules cannot be called in indefinitely.
Some of the links on this page earn us money. If you sign up with a provider after following one, that provider may pay GLP Watchdog a commission. Learn more
At a Glance
| Generic Name | Phentermine and topiramate extended-release |
| Brand Names | Qsymia |
| FDA Status | FDA-approved for chronic weight management in adults (July 17, 2012); pediatric indication for patients aged 12 years and older with obesity added December 2022. Distributed only through a Risk Evaluation and Mitigation Strategy (REMS) program because of teratogenicity and suicidality risks. Phentermine component is a DEA Schedule IV controlled substance.[1] |
| Approval Date | July 17, 2012[1] |
How Qsymia Works
Qsymia combines two mechanisms in a single capsule. Phentermine is a sympathomimetic amine structurally related to amphetamine; it stimulates norepinephrine (and to a lesser extent dopamine and serotonin) release in hypothalamic feeding centers, producing appetite suppression and a modest increase in resting energy expenditure. Topiramate is a structurally novel anticonvulsant whose appetite-suppressant and weight-reducing effects are thought to involve enhancement of GABA-A receptor activity, antagonism of AMPA/kainate glutamate receptors, blockade of voltage-gated sodium and L-type calcium channels, and weak carbonic anhydrase inhibition. The combination produces greater weight loss than either agent alone at lower doses of each component, which limits dose-related adverse effects. Topiramate also independently improves several metabolic parameters (blood pressure, triglycerides, glucose tolerance) seen in the pivotal trials.[2]
Dosing Schedule
Qsymia uses a gradual dose escalation to minimize side effects. Always follow your prescriber's guidance and the current FDA label[1].
Side Effects
Common (≥5% and ≥1.5× placebo, top-dose 15/92 mg): paresthesia (tingling in hands and feet), dizziness, dysgeusia (altered taste), insomnia, constipation, dry mouth. Other frequent effects: decreased appetite, fatigue, blurred vision, anxiety, irritability, attention/concentration difficulty, memory impairment, and word-finding problems (collectively the topiramate "cognitive fog"). Metabolic: dose-related metabolic acidosis from carbonic anhydrase inhibition, elevated serum creatinine, hypokalemia, and increased risk of kidney stones. Cardiovascular: dose-related resting heart rate increase (mean +1.6 bpm at 15/92 mg). Serious: acute angle-closure glaucoma (requires immediate discontinuation), oligohidrosis and hyperthermia (especially in adolescents in hot weather), suicidal behavior and ideation (class warning shared with all antiepileptics), mood disorders and depression, severe hypoglycemia in patients on insulin or insulin secretagogues. Teratogenicity: topiramate is associated with a 2-5× increased risk of oral cleft (cleft lip and/or cleft palate) when used during the first trimester — Qsymia is contraindicated in pregnancy, and the REMS requires monthly pregnancy testing in patients who can become pregnant plus use of effective contraception. Phentermine carries the controlled-substance class warnings: tolerance, dependence, and abuse potential (Schedule IV).[1][2]
This is not a complete list. Consult your healthcare provider or prescriber for full safety information. The complete adverse reaction profile is published in the current FDA prescribing information[1].
Clinical Trial Results
In the pivotal EQUIP trial (Allison et al. Obesity 2012, PMID 22051941; N=1,267 severely obese adults with BMI ≥35), the top dose of phentermine/topiramate 15/92 mg produced 10.9% mean body weight loss at 56 weeks versus 1.6% with placebo; 66.7% of patients on 15/92 mg lost at least 5% of body weight, and 47.2% lost at least 10%. The CONQUER trial (Gadde et al. Lancet 2011, PMID 21481449; N=2,487 overweight and obese adults with two or more weight-related comorbidities) showed 9.8% mean weight loss with 15/92 mg and 7.8% with 7.5/46 mg versus 1.2% with placebo over 56 weeks, with concurrent improvements in waist circumference, blood pressure, lipids, and fasting glucose. The SEQUEL extension (Garvey et al. Am J Clin Nutr 2012, PMID 22158731; N=675 CONQUER completers) demonstrated that benefit persists with continued treatment: at 108 weeks (about 2 years total), patients on 15/92 mg had lost 10.5% of body weight versus 1.8% with placebo, with sustained reductions in progression to type 2 diabetes and cardiometabolic risk markers.[2]
Where to Get Qsymia
These telehealth providers offer access to phentermine and topiramate extended-release or compounded equivalents with online consultations and home delivery.
Editorial score · methodology
Editorial score · methodology
Editorial score · methodology
Editorial score · methodology
Strut Health
Best for: semaglutide at $99/month, 48% under the register median
Editorial score · methodology
Editorial score · methodology
Cost Comparison
Starting prices for compounded GLP-1 medications from top providers, sorted cheapest first. Compounded phentermine and topiramate extended-release from licensed 503A and 503B pharmacies is legal under federal compounding law[3], with additional tolerances historically allowed while the molecule has appeared on the FDA Drug Shortage List[4]. Both compounded and brand-name prescriptions are generally FSA/HSA eligible under IRS Publication 502[5]. Prices may vary based on dose and promo availability.
Qsymia Head-to-Head Comparisons
Short-form verdict pages comparing Qsymia to other GLP-1 options with trial-anchored data, FDA-label dosing, and current manufacturer pricing.
See all drug-vs-drug verdicts.
Frequently Asked Questions
Sources & methodology — as of August 2026
- 1.FDA — Wegovy (semaglutide) Approval History via Drugs@FDA— U.S. Food & Drug Administration.
- 2.STEP 1 Trial — Once-Weekly Semaglutide in Adults with Overweight or Obesity (Wilding JPH et al.)— New England Journal of Medicine.PMID: 33567185.
- 3.FDA — Compounding and the 503A Pharmacy Framework— U.S. Food & Drug Administration.
- 4.FDA — Drug Shortages Database (current shortage listings)— U.S. Food & Drug Administration.
- 5.IRS Publication 502 — Medical and Dental Expenses (HSA/FSA eligibility)— Internal Revenue Service.