Key takeaways:
Qsymia (phentermine / topiramate ER) is a medication that’s used for weight loss. It’s FDA-approved for adults and children ages 12 and older who meet certain BMI criteria.
The starting Qsymia dosage is 3.75 mg phentermine/23 mg topiramate once daily for 14 days (2 weeks) followed by 7.5 mg/46 mg once daily for 12 weeks (3 months). Your prescriber may increase your dosage from there based on your response.
If you haven’t lost a certain amount of weight with Qsymia after taking the maximum dosage (15 mg/92 mg daily) for 12 weeks, your prescriber may have you stop taking it. This will require a gradual decrease in your dosage to avoid potentially serious side effects.
There are ways to save on Qsymia. GoodRx can help you access Qsymia at an exclusive cash price of $149.10. A manufacturer savings card and generic version are also available.
Qsymia is one of several oral pills FDA approved for weight loss. It comes as a capsule that contains two different medications: phentermine and topiramate ER. For the best results, you should take Qsymia while making lifestyle changes. This typically includes a low-calorie diet and routine exercise.
Qsymia is a controlled substance, meaning that it has a risk of misuse and dependence. It’s also only available at certain pharmacies and requires a special risk management program. This is because the medication can harm a fetus if you take it while you’re pregnant.
Like many medications, your Qsymia dosage can depend on how you respond to treatment. So, you may be wondering what a typical Qsymia dosage looks like. While everyone’s treatment plan can look different, we’ll review the recommended Qsymia dosages below.
What’s the typical Qsymia dosage for adults?
Qsymia is approved for adults with a body mass index (BMI) of at least 30. You may also qualify for Qsymia if you have a BMI of at least 27 along with one or more weight-related health conditions, including high blood pressure, Type 2 diabetes, or high cholesterol.
You’ll take Qsymia once a day, with or without food. It may cause insomnia if taken close to bedtime, so it’s best to take Qsymia in the morning.
The typical Qsymia dosage for weight loss in adults ranges from 7.5 mg/46 mg to 15 mg/92 mg (as phentermine / topiramate ER) daily. In most cases, you’ll start with a lower dosage, then increase it over time — more on that next.
Qsymia dosage schedule for adults
The recommended starting Qsymia dosage for adults is 3.75 mg/23 mg once daily for 14 days (2 weeks). After that, the dosage goes up to 7.5 mg/46 mg once daily for 12 weeks (3 months).
After 12 weeks, you and your prescriber should touch base about your progress with Qsymia:
If you’ve lost at least 3% of your starting body weight, you’ll likely continue taking 7.5 mg/46 mg once daily.
If you’ve lost less than 3% of your starting body weight, your prescriber may increase the dose to 11.25 mg/69 mg once daily for 14 days. This is often followed by another increase to 15 mg/92 mg once daily (the maximum recommended dose).
If you increase your dose and continue taking Qsymia, you and your prescriber should reevaluate your weight loss after another 12 weeks:
If you’ve lost at least 5% of your starting body weight, you’ll likely continue taking 15 mg/92 mg once daily.
If you’ve lost less than 5% of your starting body weight, your prescriber will likely have you stop taking Qsymia. Additional weight loss is unlikely with continued use of the medication.
Good to know: If your prescriber recommends stopping Qsymia, you’ll likely need to gradually decrease the dose to avoid withdrawal effects. Don’t stop taking it abruptly on your own. Your care team will provide instructions to help you stop taking Qsymia safely.
What’s the typical Qsymia dosage for children?
Qsymia is also approved for children ages 12 and older with a BMI in the 95th percentile or above.
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The typical Qsymia dosage for weight loss in children ranges from 7.5 mg/46 mg to 15 mg/92 mg once daily. As in adults, children will start with a lower Qsymia dosage and increase it over time based on how they respond to the medication — more on that next.
Qsymia dosage schedule for children
Qsymia dosages for kids ages 12 and older are similar to adults. But instead of using the percent of body weight lost, dosage changes are based on the percentage drop in BMI. And if a child is losing more than 2 lbs per week at any point in time, they may need a lower dose.
The starting Qsymia dosage for children is 3.75 mg/23 mg once daily for 14 days. After that, the dosage is increased to 7.5 mg/46 mg once daily for 12 weeks.
After 12 weeks, your child’s prescriber should evaluate their progress based on the following:
If there’s at least a 3% drop in BMI, they’ll likely continue 7.5 mg/46 mg once daily.
If there’s less than a 3% reduction in BMI, they’ll likely increase the dose to 11.25 mg/69 mg once daily for 14 days. Then, increase the dose to 15 mg/92 mg once daily.
After an additional 12 weeks, your child’s prescriber should reevaluate their weight loss based on the following:
If there’s at least a 5% drop in BMI, they’ll likely continue 15 mg/92 mg once daily.
If there’s less than a 5% reduction in BMI, they’ll likely stop taking Qsymia. Additional weight loss is unlikely with continued treatment.
Similar to adults, children stopping Qsymia should gradually lower the dose based on their prescriber’s instructions.
Are there any dosage adjustments for medical conditions?
Yes. If you have kidney or liver problems, you may need to take a different Qsymia dosage. This is because Qsymia can build up in your body, increasing your risk of side effects. This recommendation is the same for children and adults.
Kidney problems
The components of Qsymia, phentermine and topiramate, can both build up in the body if you have moderate or severe kidney problems.
If you have mild kidney problems, you can take the usual Qsymia dosage. But for people with moderate or severe kidney problems, the maximum recommended Qsymia dosage is 7.5 mg/46 mg once daily.
If you have end-stage kidney disease that requires dialysis, Qsymia is not recommended.
Liver problems
The phentermine in Qsymia can build up in your body if you have liver problems.
If you have mild liver disease, you can take the usual dose of Qsymia. But if you have moderate liver disease, the maximum recommended Qsymia dosage is 7.5 mg/46 mg once daily.
If you have severe liver disease, Qsymia is not recommended.
What happens if you miss a dose of Qsymia?
If you forget to take a dose of Qsymia, just skip the missed dose. Then take your usual scheduled dose the next morning. Don’t take a double or extra dose to make up for one you missed. Taking too much Qsymia can cause new or worsened side effects.
What if you need to stop taking Qsymia?
It can be dangerous to abruptly stop taking Qsymia on your own. Doing so can lead to withdrawal symptoms, including seizures.
If you’d like to stop taking Qsymia, talk to your prescriber first. They can provide instructions for gradually lowering your dose so you can stop taking it safely.
What should you do if you take too much Qsymia?
If you take an extra dose of Qsymia by mistake, let your prescriber know right away. Accidentally taking one or two extra capsules is unlikely to cause serious problems. But you may have more side effects than usual. Your prescriber can provide guidance on how to manage them or tell you if additional care is needed.
Taking a large amount of Qsymia can lead to a medical emergency and may require treatment in a hospital. Symptoms can include confusion, drowsiness, and tremors. Serious symptoms such as hallucinations, coma, and death are possible. If you or someone you know experiences a Qsymia overdose, get emergency medical care or call Poison Control at 1-800-222-1222 for guidance.
How to save on the cost of Qsymia
There are ways to save on Qsymia, which is available as a brand-name medication as well as a lower-cost generic. GoodRx can help you navigate between GoodRx coupons and copay savings cards to save money on your prescription.
Save with GoodRx. Anyone with a valid prescription, regardless of insurance status, can use GoodRx to purchase a 30-day supply of Qsymia at an exclusive cash price of $149.10. You can also use GoodRx to reduce the cost of generic Qsymia to as low as $62.80 per month.
Save with a copay savings card. If you have commercial insurance, you may be eligible to pay as little as $70 for Qsymia using a savings card from the manufacturer. A home-delivery program called Qsymia Engage is also available.
Frequently asked questions
Qsymia is a controlled substance, so only healthcare professionals with a license that allows them to write for controlled substances can prescribe it. This can vary by state, but typically includes most physicians (MD, DO). Keep in mind that Qsymia also requires registration with the FDA’s Qsymia Risk Evaluation and Mitigation Strategy (REMS) program. It requires a negative pregnancy test before starting Qsymia and monthly negative tests during treatment. So your prescriber must also be willing and able to participate in this process.
Yes, there isn’t a known interaction between ibuprofen (Advil, Motrin) and Qsymia. So it’s likely fine to take these medications together. But keep in mind that nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, aren’t the best choice for everyone. So it’s a good idea to check with your healthcare team to make sure it’s a safe option for you.
You should avoid taking Qsymia at night. It contains phentermine, a stimulant medication, that can interfere with sleep. So it’s best to take Qsymia in the morning to avoid this side effect. That being said, everyone responds to medication differently. So if Qsymia is making you drowsy or fuzzy-headed during the day, talk to your prescriber to see if it’s worth trying a bedtime dosage to see if that helps.
Qsymia is a controlled substance, so only healthcare professionals with a license that allows them to write for controlled substances can prescribe it. This can vary by state, but typically includes most physicians (MD, DO). Keep in mind that Qsymia also requires registration with the FDA’s Qsymia Risk Evaluation and Mitigation Strategy (REMS) program. It requires a negative pregnancy test before starting Qsymia and monthly negative tests during treatment. So your prescriber must also be willing and able to participate in this process.
Yes, there isn’t a known interaction between ibuprofen (Advil, Motrin) and Qsymia. So it’s likely fine to take these medications together. But keep in mind that nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, aren’t the best choice for everyone. So it’s a good idea to check with your healthcare team to make sure it’s a safe option for you.
You should avoid taking Qsymia at night. It contains phentermine, a stimulant medication, that can interfere with sleep. So it’s best to take Qsymia in the morning to avoid this side effect. That being said, everyone responds to medication differently. So if Qsymia is making you drowsy or fuzzy-headed during the day, talk to your prescriber to see if it’s worth trying a bedtime dosage to see if that helps.
The bottom line
Qsymia (phentermine / topiramate ER) is an oral weight-loss medication. It’s FDA approved for adults and children ages 12 and older who meet certain body mass index (BMI) criteria. The starting Qsymia dosage is 3.75 mg phentermine/23 mg topiramate once daily for 14 days (2 weeks). You’ll then take 7.5 mg/46 mg once daily for 12 weeks (3 months). Your prescriber may increase your dosage from there up to a maximum of 15 mg/92 mg daily based on your response.
If you haven’t lost a certain amount of weight with Qsymia after taking the maximum dosage for 12 weeks, your prescriber may have you stop taking it. This will require a gradual decrease in your dosage to avoid potentially serious side effects.
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References
Dhillon, S. (2022). Phentermine/topiramate: Pediatric first approval.
Johnson, D. B., et al. (2023). Topiramate and phentermine. StatPearls.
Julia, S., et al. (2017). Direct oral anticoagulants: A quick guide. European Cardiology.
MedlinePlus. (2023). Phentermine and topiramate.
Vivus. (n.d.). Multiple ways to save on Qysmia.
Vivus. (n.d.). Risk evaluation and mitigation strategy (REMS).
Vivus. (2022). QSYMIA- phentermine and topiramate capsule, extended release; QSYMIA- phentermine and topiramate capsule, extended release [package insert].
Vivus. (2024). Qsymia- phentermine and topiramate capsule, extended release [package insert].
