What Is Phentermine/Topiramate XR? Uses, Dosage, and What You Need to Know in 2026

What Is Phentermine/Topiramate XR?

Phentermine/Topiramate XR is an FDA-approved prescription medication used for chronic weight management in adults and adolescents 12 and older. Sold under the brand name Qsymia, it combines two active ingredients — Phentermine (an appetite suppressant) and Topiramate (an anticonvulsant) — in a single extended-release capsule taken once daily.

It is manufactured by Currax Pharmaceuticals (formerly Vivus, Inc.) and was first approved by the FDA in 2012. Phentermine/Topiramate XR is classified as a Schedule IV controlled substance and is available only through certified pharmacies under the Qsymia REMS program.

What Is Phentermine/Topiramate XR Used For?

Phentermine/Topiramate XR is approved for:

• Chronic weight management in adults with a BMI of 30 kg/m² or greater (obese)
• Chronic weight management in adults with a BMI of 27 kg/m² or greater (overweight) who have at least one weight-related condition such as high blood pressure, type 2 diabetes, or high cholesterol
• Chronic weight management in patients 12 years and older with a BMI at the 95th percentile or greater

It is meant to be used alongside a reduced-calorie diet and increased physical activity — not as a standalone treatment.

Some doctors may also prescribe it off-label for binge eating disorder or migraine prevention (due to the Topiramate component), though these are not FDA-approved uses.

How Is Phentermine/Topiramate XR Taken?

Phentermine/Topiramate XR comes in four strengths of extended-release capsules:

• 3.75 mg/23 mg (starting dose)
• 7.5 mg/46 mg (standard dose)
• 11.25 mg/69 mg (titration dose)
• 15 mg/92 mg (maximum dose)

The typical dosing schedule is:

1. Weeks 1-2: Start with 3.75 mg/23 mg once daily in the morning
2. Week 3 onward: Increase to 7.5 mg/46 mg once daily
3. If more weight loss is needed after 12 weeks: Increase to 11.25 mg/69 mg for 14 days, then to 15 mg/92 mg daily

Important dosing guidelines:

• Take it once daily in the morning to avoid insomnia
• Take it with or without food
• Swallow capsules whole — do not chew or crush
• Do not stop abruptly if on the higher dose; your doctor will taper you off to prevent seizures

Who Should Not Take Phentermine/Topiramate XR?

This medication is not safe for everyone. You should not take Phentermine/Topiramate XR if you:

• Are pregnant or planning to become pregnant — the Topiramate component causes birth defects (cleft lip/palate)
• Have glaucoma
• Have hyperthyroidism (overactive thyroid)
• Have taken an MAO inhibitor within the past 14 days (such as Phenelzine, Tranylcypromine, or Selegiline)
• Are allergic to sympathomimetic amines or any ingredient in the medication

Use with caution if you have kidney or liver problems, a history of kidney stones, mood disorders, or recent cardiovascular events. For a detailed look at drug interactions, see our guide on Phentermine/Topiramate XR drug interactions.

How Much Does Phentermine/Topiramate XR Cost?

Phentermine/Topiramate XR does not have a generic equivalent, which means it can be expensive:

• Retail cash price: $200 to $290 per month
• Qsymia Engage program: $98 per month through home delivery (LifeLine Specialty Pharmacy)
• With discount cards: As low as ~$63 per month through SingleCare at participating pharmacies

Insurance coverage varies. Many private plans cover Qsymia with prior authorization, but Medicare Part D generally does not cover weight loss medications. Some state Medicaid programs may cover it.

For a complete breakdown of savings options, read how to save money on Phentermine/Topiramate XR.

Final Thoughts

Phentermine/Topiramate XR (Qsymia) is one of the most effective FDA-approved weight loss medications available, combining two proven ingredients in a single daily capsule. It requires a prescription from a REMS-certified provider, monthly pregnancy testing for women of childbearing age, and can only be filled at certified pharmacies.

If you think Phentermine/Topiramate XR might be right for you, talk to your doctor about whether you meet the eligibility criteria. To learn more about side effects or how this medication works, check out our other guides. Ready to find it? Search for Phentermine/Topiramate XR on Medfinder.