Qsymia (Phentermine + Topiramate ER) for Weight Loss: FDA Label, CONQUER Evidence & How It Compares to GLP-1s (2026)

Qsymia is the strongest non-GLP-1 oral prescription appetite suppressant FDA-approved in the United States. The fixed-dose combination of phentermine (a sympathomimetic anorexiant) and topiramate ER (an anticonvulsant whose appetite-suppressing effect is a documented side effect) produces ~7.8-9.8% mean body-weight loss at 56 weeks per the CONQUER phase 3 trial (Lancet 2011, PMID 21481449), with the EQUIP and SEQUEL trials extending the evidence to higher-BMI patients and 2-year follow-up. Qsymia is DEA Schedule IV (phentermine component) and has a Risk Evaluation and Mitigation Strategy (REMS) program for topiramate's fetal toxicity — distributed only through certified pharmacies. Below: the verbatim FDA label, the three pivotal trials, the side-effect profile, and how Qsymia fits in 2026's expanded weight-loss landscape.

What is Qsymia?

Qsymia is a fixed-dose combination capsule containing two FDA-approved active ingredients:

• Phentermine — a sympathomimetic amine anorectic. Phentermine alone has been FDA-approved as a weight-loss drug since 1959. It works by stimulating norepinephrine release in the central nervous system, which reduces appetite. Phentermine alone is DEA Schedule IV and is labeled for short-term use (typically up to 12 weeks).
• Topiramate extended-release — an anticonvulsant FDA-approved for epilepsy and migraine prophylaxis. Patients taking topiramate for those indications consistently reported weight loss as a side effect, which led to the development of Qsymia. The mechanism by which topiramate suppresses appetite is not fully understood — proposed mechanisms include modulation of GABA neurotransmission, AMPA/kainate glutamate receptors, and carbonic anhydrase activity in the hypothalamus.

Qsymia (NDA 022580) was FDA-approved on July 17, 2012 for chronic weight management in adults. The original sponsor was Vivus Inc. (now Vivus LLC; sold to Sequel Med Tech in 2024). The drug is dispensed only through certified pharmacies enrolled in the Qsymia REMS program because of topiramate's known fetal toxicity (cleft lip / cleft palate risk in first-trimester exposure).

FDA-approved indication (verbatim from §1)

Per the Qsymia DailyMed label §1 INDICATIONS AND USAGE:

“Qsymia is indicated as an adjunct to a reduced-calorie diet and increased physical activity for chronic weight management in:
• Adults with an initial body mass index (BMI) of 30 kg/m² or greater (obese), or
• Adults with an initial body mass index of 27 kg/m² or greater (overweight) in the presence of at least one weight-related comorbidity such as hypertension, type 2 diabetes mellitus, or dyslipidemia.
• Pediatric patients 12 years of age and older with a BMI in the 95th percentile or greater standardized for age and sex.”

The 12-and-older pediatric indication was added in a 2022 FDA approval — making Qsymia one of the few FDA-approved anti-obesity medications with an adolescent indication. Wegovy and Saxenda are the GLP-1 RAs with comparable 12-and-older approvals.

Dosing schedule

Qsymia comes in 4 fixed-dose strengths labeled by the phentermine / topiramate ER milligram pair:

Per the label §2 DOSAGE AND ADMINISTRATION: patients start on 3.75/23 daily for 14 days, escalate to 7.5/46 daily for 12 weeks (the recommended dose), and only escalate further to 11.25/69 then 15/92 if weight loss has not reached threshold targets. The label specifies a stop rule: if the patient has not lost at least 3% of baseline body weight after 12 weeks on the 7.5/46 dose, either escalate to 15/92 or discontinue the drug. If the 15/92 dose has not produced at least 5% baseline weight loss after another 12 weeks, discontinue gradually (over 1 week, to avoid topiramate withdrawal seizures).

CONQUER trial — the canonical phase 3 evidence

CONQUER (Gadde et al., Lancet 2011, PMID 21481449) is the canonical phase 3 trial for Qsymia. Verbatim from the published paper:

• Design: 56-week, randomized, placebo-controlled, phase 3 trial. n=2,487 adults with BMI 27-45 plus 2+ weight-related comorbidities.
• Arms: placebo, 7.5/46 mg phentermine/topiramate-CR, or 15/92 mg phentermine/topiramate-CR — once daily.
• All arms received a reduced-calorie diet (-500 kcal/day deficit) plus a behavioral lifestyle intervention.
• Primary endpoint — mean percent body-weight change at 56 weeks (ITT, last observation carried forward):
  • Placebo: -1.2%
  • 7.5/46 mg dose: -7.8%
  • 15/92 mg dose: -9.8%
• Categorical responder analysis (≥5% baseline weight loss at 56 weeks): 21% placebo, 62% on 7.5/46, 70% on 15/92.
• Secondary endpoints: reductions in waist circumference, blood pressure, fasting glucose, and lipid profile in both Qsymia arms vs placebo.

EQUIP trial — severely obese (BMI ≥35) population

EQUIP (Allison et al., Obesity 2012, PMID 22051941) extended the CONQUER findings to a severely obese population:

• Design: 56-week, randomized, placebo-controlled phase 3 trial. n=1,267 adults with BMI ≥35 (severely obese, regardless of comorbidities).
• Arms: placebo, 3.75/23 mg, or 15/92 mg phentermine/topiramate-CR.
• Primary endpoint — mean percent body-weight change at 56 weeks:
  • Placebo: -1.6%
  • 3.75/23 dose: -5.1%
  • 15/92 dose: -10.9%
• Note: the 10.9% top-dose mean weight loss in the severely-obese EQUIP population was higher than the 9.8% in the CONQUER mixed-BMI population — consistent with the general principle that absolute weight loss is larger in patients with higher baseline BMI.

SEQUEL trial — 2-year sustained weight loss

SEQUEL (Garvey et al., Am J Clin Nutr 2012, PMID 22158731) is the 2-year extension study from CONQUER:

• Design: 52-week extension after the original 56-week CONQUER trial — total exposure 108 weeks (~2 years). Patients who completed CONQUER were eligible to continue on their assigned blinded treatment.
• n=675 completers (sub-population of CONQUER who consented to the extension).
• Mean percent body-weight loss at 108 weeks (2 years from baseline):
  • Placebo: -1.8%
  • 7.5/46 mg dose: -9.3%
  • 15/92 mg dose: -10.5%
• SEQUEL was the first phase 3 anti-obesity trial to demonstrate sustained weight loss past 1 year on a non-GLP-1 oral therapy at the time of its publication (2012, pre-Saxenda + pre-Wegovy).

Most common adverse reactions (verbatim from §6)

Per the DailyMed §6 ADVERSE REACTIONS section, events reported by ≥5% of patients on the recommended (7.5/46) or top (15/92) dose AND more frequently than placebo:

• Paresthesia (tingling sensations in fingers/toes/face) — ~14% on 7.5/46, ~21% on 15/92 vs ~2% placebo. Topiramate effect on sodium channels.
• Dizziness — ~7% on 7.5/46, ~10% on 15/92
• Dysgeusia (altered taste) — ~7% on 7.5/46, ~10% on 15/92. Patients commonly report carbonated drinks tasting flat or unpleasant.
• Insomnia — ~6% on 7.5/46, ~10% on 15/92. Phentermine effect.
• Constipation — ~16% on 7.5/46, ~17% on 15/92
• Dry mouth — ~14% on 7.5/46, ~21% on 15/92. Topiramate effect.
• Cognitive disorders (difficulty concentrating, memory issues, language disturbance) — ~5-8% on 15/92. Topiramate effect; patients sometimes describe this as “Dopamax” cognitive fog.

REMS program and contraindications

Qsymia is dispensed only through pharmacies enrolled in the Qsymia Risk Evaluation and Mitigation Strategy (REMS) program. The REMS exists because topiramate causes a documented increased risk of cleft lip / cleft palate when used in the first trimester of pregnancy. Pregnancy testing is required before starting Qsymia and monthly thereafter for women of reproductive potential, and contraception use is mandated.

Verbatim contraindications from §4:

• Pregnancy (Pregnancy Category X)
• Glaucoma
• Hyperthyroidism
• During or within 14 days of MAOI treatment
• Hypersensitivity to phentermine, topiramate, sympathomimetic amines, or any component of the formulation

DEA scheduling status

Phentermine alone is a DEA Schedule IV controlled substance — the lowest controlled-substance tier, indicating recognized but limited abuse potential. Qsymia, as the phentermine/topiramate combination, is NOT itself DEA scheduled at the federal level because phentermine is dose-titrated within the combination. Some states classify Qsymia as a controlled substance at the state level; check your state pharmacy regulations.

For comparison: GLP-1 receptor agonists (Wegovy, Zepbound, Saxenda, Foundayo) are NOT DEA scheduled. Phentermine alone IS DEA Schedule IV. Contrave (naltrexone + bupropion) is NOT scheduled.

How Qsymia compares to GLP-1 alternatives

Qsymia's 9.8% top-dose mean weight loss at 56 weeks (CONQUER) is competitive with older GLP-1s but smaller than the modern semaglutide and tirzepatide phase 3 numbers:

• Zepbound (tirzepatide 15 mg, SURMOUNT-1): ~20.9% at 72 weeks (NEJM 2022)
• Wegovy (semaglutide 2.4 mg, STEP-1): ~14.9% at 68 weeks (NEJM 2021, PMID 33567185)
• Foundayo (orforglipron, oral GLP-1): ~12-15% range from late-phase trials (label data)
• Qsymia 15/92 (CONQUER): ~9.8% at 56 weeks
• Qsymia 7.5/46 (CONQUER): ~7.8% at 56 weeks
• Saxenda (liraglutide 3 mg, SCALE): ~5-8% at 56 weeks
• Contrave (naltrexone + bupropion, COR-I): ~5.0-6.4% at 56 weeks

Trade-offs vs the modern GLP-1s:

• Qsymia is oral, not injectable. The GLP-1 oral options as of 2026 are Foundayo (orforglipron) for weight management and Rybelsus (oral semaglutide) for diabetes. Qsymia is the strongest oral non-GLP-1 option.
• Qsymia has a different side-effect profile. GI side effects (nausea, vomiting, diarrhea) dominate on GLP-1s. Qsymia produces paresthesia, dysgeusia, dry mouth, insomnia, and cognitive effects (the topiramate contribution). Patients who can't tolerate GLP-1 GI side effects sometimes do well on Qsymia and vice versa.
• Qsymia has REMS distribution. Only certified pharmacies dispense it. GLP-1s do not have REMS but do carry the thyroid C-cell tumor boxed warning.
• Qsymia has 13+ years of post-marketing surveillance. Wegovy has 5 years; Zepbound 3 years; Foundayo just over 1 month. Patients prioritizing a longer real-world safety record may prefer Qsymia.
• Qsymia contains a DEA-scheduled component. Some patients want to avoid controlled-substance components entirely; for them, Wegovy / Zepbound / Saxenda / Contrave / Xenical are the alternatives.

For the full side-by-side, see Best Appetite Suppressant 2026 and FDA-approved weight loss medications hub.

Cost (2026)

Qsymia is brand-only — no generic phentermine/topiramate ER combination has been FDA-approved as of 2026-05-09. Cash-pay retail pricing typically runs $200-500/month depending on the pharmacy and dose. Manufacturer savings programs from Vivus/Sequel Med Tech can reduce the price for commercially insured patients. Insurance coverage for Qsymia is uneven — many plans treat it as an obesity medication subject to prior authorization with the same BMI/comorbidity documentation requirements as Wegovy and Zepbound (see our Cigna PA guide and Aetna PA guide for the verbatim payer-policy language). Some plans explicitly exclude all anti-obesity medications, in which case Qsymia is cash-pay.

For comparison, the cheapest cash-pay oral weight-loss options in 2026:

• Generic phentermine (alone): ~$9-30/month at retail pharmacies — short-term use only (typically ≤12 weeks)
• Foundayo (orforglipron, oral GLP-1): $149/month at LillyDirect / Amazon Pharmacy
• Wegovy oral pill 1.5/4 mg: $149/month at NovoCare through Aug 31, 2026
• Qsymia (brand): ~$200-500/month cash-pay
• Contrave: ~$200-300/month cash-pay
• Generic orlistat / OTC alli (60 mg): ~$30-60/month

Who should consider Qsymia?

• Patients who can't tolerate GLP-1 GI side effects but still want a meaningfully effective prescription appetite suppressant
• Patients who prefer an oral pill over an injection — though Foundayo (oral GLP-1) is now an alternative oral option as of April 2026
• Patients with a personal or family history of medullary thyroid carcinoma (MTC) or MEN 2 — all GLP-1s are contraindicated; Qsymia is an alternative
• Pediatric patients 12 and older with BMI ≥95th percentile — Qsymia is one of the few FDA-approved AOMs with an adolescent indication
• Patients prioritizing long-established post-marketing safety surveillance over the modern GLP-1 effect-size ceiling

Who should NOT take Qsymia?

• Pregnancy or planning pregnancy (Category X + REMS for fetal toxicity from topiramate)
• Glaucoma (contraindication)
• Hyperthyroidism (contraindication)
• Recent / current MAOI use (within 14 days)
• History of seizures requiring topiramate discontinuation
• History of substance abuse / phentermine intolerance — phentermine is DEA Schedule IV
• Patients prioritizing the largest possible weight loss — Zepbound (tirzepatide) at ~20.9% beats Qsymia's ~9.8% in head-to-head indirect comparison