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Qsymia is a prescription capsule that combines two older medicines, phentermine and topiramate, in an extended-release form. The FDA approved it in July 2012 for long-term weight management in adults with obesity, or with overweight plus at least one weight-related health problem, and in June 2022 added adolescents aged 12 and older with obesity. It is taken once a day in the morning alongside a reduced-calorie diet and more physical activity. In its two main year-long trials, average weight loss ranged from about 5% to 11% depending on strength, compared with 1% to 2% on placebo. Because topiramate can cause birth defects, Qsymia is sold only through certified pharmacies under an FDA safety program.
Peptide Labs does not sell Qsymia, phentermine or any prescription drug. This article is general information, not medical advice. Whether any weight-loss medicine suits a person is a decision for a licensed prescriber.
Key Takeaways
- Qsymia is phentermine plus extended-release topiramate, made by Vivus and FDA-approved since July 2012.
- It is approved for long-term weight management in adults and, since June 2022, in teens 12 and older with obesity.
- In the Vivus-funded CONQUER trial, average weight change after 56 weeks was -7.8% and -9.8% on two strengths vs -1.2% on placebo.
- The most common side effects are tingling (paraesthesia), dizziness, altered taste, trouble sleeping, constipation and dry mouth.
- It must not be used in pregnancy; the label calls for a negative pregnancy test before starting and every month after.
- The label says to stop if an adult has not lost at least 5% of starting weight after 12 weeks on the highest strength.
What is Qsymia?
Qsymia (phentermine-topiramate extended-release) pairs a stimulant-type appetite suppressant with an anti-seizure medicine. Phentermine is described on the label as a sympathomimetic amine anorectic, a stimulant related to amphetamine that likely reduces appetite through the brain’s hypothalamus. It is a Schedule IV controlled substance. Topiramate is an antiepileptic (anti-seizure) medicine and is not controlled; the label says it may reduce appetite and increase fullness, but that the exact way either ingredient causes weight loss is not known. The table summarizes the current label, published on DailyMed in April 2026.
| Label item | Qsymia |
|---|---|
| Active ingredients | Phentermine and topiramate (extended-release) |
| Maker | Vivus |
| First FDA approval | July 2012 |
| Approved for | Adults with obesity or overweight plus a weight-related condition; teens 12+ with obesity |
| How it is taken | One capsule once daily in the morning, with or without food |
| Controlled substance | Yes, Schedule IV (because of phentermine) |
| Safety program | REMS: dispensed only by certified pharmacies |
| Pregnancy | Contraindicated; monthly pregnancy tests for people who can become pregnant |
| Generic | FDA-approved generics since June 2024 |
The label notes two limits: its effect on heart attacks, strokes and cardiovascular deaths has not been established, and its safety with other weight-loss products, including over-the-counter drugs and herbal products, has not been studied. People asking about the over-the-counter option orlistat can read our guide to alli.
How phentermine-topiramate is started and reviewed
The label starts at a low strength and raises it in steps over several weeks. It advises taking the capsule in the morning, because evening use can cause insomnia. Before starting, it recommends a blood chemistry check that includes bicarbonate, creatinine and potassium, repeated periodically, plus a negative pregnancy test for anyone who can become pregnant.
The label also builds in a response check. After 12 weeks on a given strength, the prescriber evaluates weight loss in adults, or the drop in body mass index (BMI) in teens. If the response is too small, the strength may be increased. After 12 weeks on the highest strength, the label says to stop Qsymia in an adult who has not lost at least 5% of starting weight, because further meaningful loss is unlikely. The highest strength must be stopped gradually, since stopping topiramate suddenly can trigger seizures.
Qsymia trial results
Two Vivus-funded, double-blind, placebo-controlled trials supported approval. Each lasted 56 weeks and recommended a reduced-calorie diet with lifestyle counseling to everyone, including the placebo groups:
| Trial (published) | Who took part | Placebo | Lower strength tested | Higher strength tested |
|---|---|---|---|---|
| EQUIP (Obesity 2012) | 1,267 adults with BMI 35 or higher | -1.6% | -5.1% | -10.9% |
| CONQUER (Lancet 2011) | 2,487 adults with BMI 27 to 45 and 2+ related conditions | -1.2% | -7.8% | -9.8% |
| Teen trial (NEJM Evidence 2022) | 223 adolescents aged 12 to 16 | BMI +3.3% | BMI -4.8% | BMI -7.1% |
In CONQUER, 62% and 70% of people on the two Qsymia strengths lost at least 5% of their weight, vs 21% on placebo, and 37% and 48% lost at least 10%, vs 7%. The figures need context: 40% of EQUIP participants and 31% of CONQUER participants withdrew before week 56, and missing values were filled in by carrying the last measurement forward. In SEQUEL, a one-year extension of CONQUER in which 676 participants continued, average weight change after 108 weeks was -9.3% and -10.5% vs -1.8% on placebo. In the teen trial, also funded by Vivus, 38% of participants withdrew before week 56.
Qsymia side effects
The label lists the most common side effects in adults as paraesthesia (tingling in the hands, feet or face), dizziness, dysgeusia (an altered, often metallic taste), insomnia, constipation and dry mouth. In the year-long adult trials, comparing placebo with the highest strength:
- Tingling: 2% vs 20%
- Dry mouth: 3% vs 19%
- Constipation: 6% vs 16%
- Altered taste: 1% vs 9%
- Insomnia: 5% vs 9%
- Dizziness: 3% vs 9%
In the teen trial, the most common side effects were depression, dizziness, joint pain, fever, flu and ligament sprain. Heart rate also rises slightly: in an 8-week monitoring study, average 24-hour heart rate was 3.6 beats per minute higher than with placebo. The label advises against excessive alcohol, because alcohol and sedating medicines can add to dizziness, drowsiness and thinking problems.
Serious warnings on the Qsymia label
- Birth defects. Topiramate taken in the first trimester raises the risk of major birth defects, including cleft lip and cleft palate, and of babies born small for gestational age. Effective contraception is advised, and the REMS limits dispensing to certified pharmacies. Hormonal birth control pills may cause spotting with Qsymia, but the label says this does not raise pregnancy risk.
- Mood, suicidal thoughts and sleep. Like other anti-seizure medicines, topiramate carries a warning about suicidal thoughts and behavior. Depression, anxiety and insomnia were more common than with placebo.
- Thinking and memory. Problems with attention, memory and word-finding were reported. The label advises caution with driving until a person knows how Qsymia affects them.
- Eyes. Sudden nearsightedness with a type of glaucoma, and visual field defects, have been reported with topiramate.
- Blood chemistry and kidneys. Metabolic acidosis (low bicarbonate), low potassium, a rise in creatinine and kidney stones can occur; the label advises drinking more fluids to lower kidney stone risk.
- Heat. Reduced sweating and raised body temperature have been reported, mostly in children.
- Teens. Height gain was slower than with placebo, and bone mineral density increased less over a year.
- Allergic and skin reactions. Rare but serious reactions such as DRESS, Stevens-Johnson syndrome, anaphylaxis and angioedema have been reported with topiramate.
Who should not take Qsymia
The label says Qsymia must not be used during pregnancy, by people with glaucoma or an overactive thyroid, by anyone taking an MAO inhibitor antidepressant or within 14 days of stopping one, or by people allergic to phentermine, topiramate or the capsule’s ingredients. Breastfeeding is not recommended, and the capsules contain the dye tartrazine (FD&C Yellow No. 5), which can cause allergic-type reactions in some people.
Qsymia vs phentermine
Phentermine on its own has been sold for decades. Its label approves it only as a short-term addition to diet and exercise, “a few weeks” in the label’s words. Qsymia is approved for long-term use. The Qsymia label also notes that tolerance has been seen with stimulant drugs of this class.
One 28-week trial, published in Obesity in 2013, compared the Qsymia combination with each of its parts taken alone and with placebo. Average weight loss was 8.5% and 9.2% on two combination strengths, greater than with the matching amounts of phentermine or topiramate alone, and 1.7% on placebo. At least 5% of body weight was lost by 62% to 66% of people on the combination and 43% to 46% on phentermine alone. Supplements sold as “phentermine alternatives” are not phentermine; see do fat burners work.
How Qsymia compares with GLP-1 medicines
No head-to-head trial has compared Qsymia with Wegovy or Zepbound, so cross-trial comparisons are only rough. Qsymia’s year-long trials reported average losses of about 5% to 11% depending on strength, while the GLP-1 trials reported 15% or more over 68 to 72 weeks in different populations. Qsymia is a daily capsule with a controlled-substance ingredient and a pregnancy program; the GLP-1 medicines are mostly weekly injections, with tablet forms now available, and carry their own warnings. Our guide to GLP-1 weight loss results covers those trials, GLP-1 side effects covers their safety, and Ozempic alternatives and appetite suppressants list the other approved options.
Generic phentermine-topiramate
FDA records show generic phentermine and topiramate extended-release capsules were approved in June 2024 and again in June 2025, from two different manufacturers. A pharmacist can confirm which versions are available and how the pregnancy safety program applies.
Frequently Asked Questions
What is Qsymia?
Qsymia is a once-daily prescription capsule that combines phentermine and extended-release topiramate. It is FDA-approved for long-term weight management in adults with obesity or overweight plus a related condition, and in teens 12 and older with obesity.
How much weight do people lose on Qsymia?
In the CONQUER trial, average weight change after 56 weeks was -7.8% and -9.8% on two strengths vs -1.2% on placebo. In EQUIP, which enrolled people with a BMI of 35 or higher, it was -10.9% on the higher strength. Many participants withdrew early, and results vary.
What are the most common Qsymia side effects?
Tingling in the hands, feet or face, dizziness, altered taste, trouble sleeping, constipation and dry mouth. Mood changes, memory and concentration problems, kidney stones and low bicarbonate are among the less common but important warnings.
Is Qsymia a controlled substance?
Yes. It contains phentermine, a Schedule IV controlled substance. Topiramate is not controlled.
Why is a pregnancy test needed for Qsymia?
Topiramate taken early in pregnancy raises the risk of birth defects such as cleft lip and palate. The label calls for a negative test before starting and monthly during use, and the drug is dispensed only through certified pharmacies.
What is the difference between Qsymia vs phentermine alone?
Phentermine alone is labeled for short-term use of a few weeks. Qsymia adds topiramate, is labeled for long-term use, and in a 28-week trial produced more weight loss than either ingredient alone.
Peptide Labs does not sell these drugs. This article is general information, not medical advice. Read the Medication Guide that comes with a prescription, and ask a pharmacist or prescriber how this information applies to you.
Last reviewed September 2026.
Related guides: Phentermine: What It Is, Side Effects and Safety Facts, Ozempic Alternatives: FDA-Approved Options, OTC Facts and What to Avoid, Appetite Suppressants: Prescription Drugs, Natural Options and the Risks.