What Is Qsymia? Uses, Dosage, and What You Need to Know in 2026

Qsymia (pronounced kyoo-SIM-ee-ah) is an FDA-approved prescription medication for chronic weight management. It's a once-daily extended-release capsule that combines two active ingredients: phentermine (an appetite suppressant) and topiramate (an anticonvulsant known to cause weight loss as a side effect). Together, they work synergistically to help reduce appetite and calorie intake at doses lower than either drug requires alone.

What Is Qsymia Approved For?

Qsymia is FDA-approved as an adjunct to a reduced-calorie diet and increased physical activity for:

Adults with obesity (initial BMI ≥30 kg/m²)

Overweight adults (BMI ≥27 kg/m²) with at least one weight-related condition such as hypertension, type 2 diabetes, or dyslipidemia

Pediatric patients aged 12 and older with obesity (BMI at or above the 95th percentile for age and sex) — approved in 2022

It was first approved by the FDA in July 2012—the first prescription weight-loss medication approved in the U.S. in 13 years at the time.

What Are the Ingredients in Qsymia?

Qsymia contains two active ingredients in a single extended-release capsule:

Phentermine: A sympathomimetic amine that stimulates the central nervous system to suppress appetite, similar to amphetamines but at much lower doses. Phentermine is a Schedule IV controlled substance.

Topiramate (extended-release): An antiepileptic drug that reduces appetite through several mechanisms including enhancing GABA activity and modulating glutamate receptors. Topiramate is not a controlled substance.

The combination works synergistically, producing greater weight loss at lower doses of each component than would be achievable with either drug alone. This reduces the side effect burden while maintaining efficacy.

Qsymia Dosage: How Much Do You Take?

Qsymia comes in four dose strengths. Treatment follows a step-up titration schedule:

Starting dose: 3.75/23 mg once daily for 14 days (titration)

Recommended dose: 7.5/46 mg once daily (for first 12 weeks, provider evaluates progress)

Escalation (if insufficient response): 11.25/69 mg once daily for 14 days, then increase to maximum

Maximum dose: 15/92 mg once daily

Key administration rules:

Take once daily in the morning (taking it later in the day can cause insomnia)

Can be taken with or without food

Swallow capsules whole—do not crush, chew, or split

Do not stop Qsymia 15/92 mg abruptly—taper by taking every other day for at least one week to avoid seizure risk

How Effective Is Qsymia?

In clinical trials, Qsymia produced significant weight loss when combined with diet and exercise. Key efficacy data:

1 in 5 adults taking the top dose (15/92 mg) lost at least 20% of their body weight

1 in 4 adolescents taking the top dose lost 20% or more of body weight

In a 56-week adolescent study, patients on 15/92 mg lost an average of 7.1% of BMI, while the placebo group gained an average of 3.3% of BMI

Average adult weight loss at the recommended dose (7.5/46 mg): approximately 8–9% of baseline body weight over one year

Who Should NOT Take Qsymia?

Qsymia is contraindicated in people who:

Are pregnant or planning to become pregnant (serious birth defect risk)

Have glaucoma

Have hyperthyroidism

Are taking MAO inhibitors (or have within the past 14 days)

Have a known allergy to phentermine, topiramate, or sympathomimetic amines

Finding Qsymia at a Pharmacy

Qsymia can only be dispensed at pharmacies certified under the FDA's Qsymia REMS program. If you're having trouble finding a certified pharmacy near you, medfinder calls pharmacies on your behalf to locate which ones have your specific dose in stock.

To learn exactly how Qsymia works at the molecular level, see our article How Does Qsymia Work? Mechanism of Action Explained in Plain English.