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Qsymia

Generic name: phentermine and topiramateFEN-ter-meen-and-toe-PIR-a-mate ]
Drug class: Anorexiants

Medically reviewed by Sophia Entringer, PharmD. Last updated on Oct 26, 2022.

What is Qsymia?

Qsymia contains a combination of phentermine and topiramate in an extended-release capsule. Phentermine is an appetite suppressant similar to an amphetamine. Topiramate is typically used as a seizure medication, also called an anticonvulsant.

Qsymia is used together with diet and exercise to help some adults and children 12 years and older with obesity, or some overweight adults who also have weight-related medical problems such as diabetes, high cholesterol, or high blood pressure, to lose weight and keep the weight off.

Qsymia will not treat any of these underlying conditions. Keep using any other medicines your doctor has prescribed to treat these conditions.

Warnings

Do not use Qsymia if you are pregnant or if you become pregnant. This medicine may increase the risk of a birth defect called cleft lip and palate in a newborn.

You should not take Qsymia if you are allergic to phentermine (Adipex-P, Oby-Cap, Suprenza, T-Diet, Zantryl) or topiramate (Topamax), or if you have glaucoma or overactive thyroid.

Before you take Qsymia, tell your doctor if you have high blood pressure, heart disease, diabetes, liver or kidney disease, low blood levels of potassium, or if you have had a heart attack or stroke in the past 6 months.

Phentermine may be habit-forming and should be used only by the person for whom it was prescribed. Keep the medication in a secure place where others cannot get to it. Do not stop taking Qsymia suddenly, or you could have a seizure (convulsions). You may need to use less and less before you stop the medication completely. Ask your doctor how to avoid seizures when you stop using Qsymia

Topiramate may cause vision problems that can be permanent if not treated quickly. Call your doctor right away if you have a sudden decrease in vision.

Some people have thoughts about suicide while taking topiramate. Stay alert to changes in your mood or symptoms. Report any new or worsening symptoms to your doctor.

Qsymia can increase your resting heart rate. Tell your doctor if you have fast or pounding heartbeats while you are resting.

Before taking this medicine

Do not use Qsymia if you have used an MAO inhibitor in the past 14 days. A dangerous drug interaction could occur. MAO inhibitors include isocarboxazid, linezolid, methylene blue injection, phenelzine, rasagiline, selegiline, tranylcypromine, and others.

You should not use Qsymia if you are allergic to phentermine or topiramate, or if you have:

You may need to have a negative pregnancy test before starting this treatment. Do not use Qsymia if you are pregnant. Stop taking this medicine and call your doctor right away if you become pregnant.

Topiramate may increase the risk of cleft lip and palate in a newborn. This birth defect occurs early in pregnancy, and can develop even before you know you are pregnant. Weight loss during pregnancy also can harm an unborn baby, even if you are overweight. Use effective birth control to prevent pregnancy while you are using Qsymia.

Qsymia is not FDA-approved for use by anyone younger than 12 years old.

To make sure Qsymia is safe for you, tell your doctor if you have:

Topiramate can increase the level of acid in your blood (metabolic acidosis). This can weaken your bones, cause kidney stones, or cause growth problems in children or harm to an unborn baby. You may need blood tests to make sure you do not have metabolic acidosis.

Some people have thoughts about suicide while taking topiramate. Your doctor will need to check your progress at regular visits. Your family or other caregivers should also be alert to changes in your mood or symptoms.

You should not breast-feed while using Qsymia.

How should I take Qsymia?

Take Qsymia exactly as prescribed by your doctor. Follow all directions on your prescription label and read all medication guides or instruction sheets.

Your healthcare provider should start you on a diet and exercise program when you start taking Qsymia. Stay on this program during your treatment. 

Take this medicine each morning, with or without food.

Drink plenty of water each day to prevent dehydration or kidney stones while you are taking Qsymia.

To start treatment with Qsymia:

After taking Qsymia for 12 weeks:

If your healthcare provider increases the dose of Qsymia:

Stopping Qsymia treatment:

Your healthcare provider should tell you to stop taking Qsymia if you have not lost a certain amount of weight or do not have a certain decrease in BMI for children 12 years and older, after an additional 12 weeks of treatment on the higher dose.

Do not stop taking Qsymia without talking to your healthcare provider. Stopping Qsymia suddenly can cause serious problems, such as seizures. Your healthcare provider will tell you how to stop taking Qsymia slowly.

Store at room temperature away from moisture and heat.

Phentermine may be habit-forming. Misuse can cause addiction, overdose, or death. Keep the medication in a place where others cannot get to it. Selling or giving away this medicine is against the law.

Dosing information

Usual Adult Dose of Qsymia for Weight Loss:

-Initial dose: Take one capsule of the lowest dose (phentermine 3.75 mg/topiramate 23 mg extended-release) orally once a day in the morning for the first 14 days.

-Maintenance dose: After 14 days, take one capsule of the recommended dose (phentermine 7.5 mg/topiramate 46 mg extended-release) orally once a day in the morning.

Comments:
-Weight loss should be evaluated after 12 weeks with phentermine 7.5 mg/topiramate 46 mg extended-release. If a patient has not lost at least 3% of baseline body weight increase the dosage to phentermine 11.25 mg/topiramate 69 mg) orally once daily for 14 days; followed by an increase in the dosage to phentermine 15 mg/topiramate 92 mg orally once daily. Weight loss should be evaluated after 12 weeks with phentermine 15 mg/topiramate 92 mg. If a patient has not lost at least 5% of baseline body weight, discontinue treatment, as it is unlikely that the patient will achieve and sustain clinically meaningful weight loss at this dose. Discontinue phentermine 15 mg/topiramate 92 mg dose gradually by taking once daily every other day for at least one week prior to stopping treatment altogether.

Use: Adjunct to a reduced-calorie diet and increased physical activity for chronic weight management in patients with an initial body mass index (BMI) of 30 kg/m2 or greater (obese) OR 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.

Usual Pediatric Dose of Qsymia for Weight Loss:

-Initial dose: Take one capsule of the lowest dose (phentermine 3.75 mg/topiramate 23 mg extended-release) orally once a day in the morning for the first 14 days.

-Maintenance dose: After 14 days, take one capsule of the recommended dose (phentermine 7.5 mg/topiramate 46 mg extended-release) orally once a day in the morning.

Comments:
-Weight loss should be evaluated after 12 weeks with phentermine 7.5 mg/topiramate 46 mg extended-release. If a pediatric patient has not lost at least 3% of baseline BMI, increase the dosage to phentermine 11.25 mg/topiramate 69 mg) orally once daily for 14 days; followed by an increase in the dosage to phentermine 15 mg/topiramate 92 mg orally once daily. Weight loss should be evaluated after 12 weeks with phentermine 15 mg/topiramate 92 mg. If a pediatric patient has not lost at least 5% of baseline BMI, discontinue treatment, as it is unlikely that the patient will achieve and sustain clinically meaningful weight loss at this dose. Discontinue phentermine 15 mg/topiramate 92 mg dose gradually by taking once daily every other day for at least one week prior to stopping treatment altogether.

Use: Adjunct to a reduced-calorie diet and increased physical activity for chronic weight management in pediatric patients aged 12 years and older with BMI in the 95th percentile or greater standardized for age and sex.

What happens if I miss a dose?

Skip the missed dose and use your next dose at the regular time. Do not use two doses at one time.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222. An overdose of phentermine and topiramate can be fatal.

Overdose symptoms may include confusion, hallucinations, panic, personality changes, tremors, a restless feeling followed by severe tiredness, nausea, vomiting, diarrhea, stomach cramps, irregular heartbeat, rapid breathing, seizure, or coma.

What to avoid

Do not take other weight-loss products without your doctor's advice.

Ketogenic or "ketosis" diets that are high in fat and low in carbohydrates can increase the risk of metabolic acidosis. Avoid the use of such diets while you are taking this medicine.

Drinking alcohol with this medicine can cause side effects.

Avoid driving or hazardous activity until you know how this medicine will affect you. Your reactions could be impaired.

Avoid becoming overheated or dehydrated in hot weather. Topiramate can decrease sweating and increase body temperature, leading to life-threatening dehydration.

Qsymia side effects

Get emergency medical help if you have signs of an allergic reaction to Qsymia: (hives; difficult breathing; swelling in your face or throat), or a severe skin reaction (fever, sore throat, burning eyes, skin pain, red or purple skin rash with blistering and peeling).

Report any new or worsening symptoms to your doctor, such as: mood or behavior changes, anxiety, panic attacks, trouble sleeping, or if you feel impulsive, irritable, agitated, hostile, aggressive, restless, hyperactive (mentally or physically), depressed, or have thoughts about suicide or hurting yourself.

Call your doctor at once if you have:

Common Qsymia side effects may include:

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect Qsymia?

Qsymia can cause irregular vaginal bleeding while you are taking birth control pills. This should not make the pills less effective in preventing pregnancy.

Using this medicine with other drugs that make you drowsy can worsen this effect. Ask your doctor before using opioid medication, a sleeping pill, a muscle relaxer, or medicine for anxiety or seizures.

Tell your doctor about all your other medicines, especially:

This list is not complete. Other drugs may interact with phentermine and topiramate, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.

Popular FAQ

Qsymia is a combination of two drugs, phentermine and extended-released topiramate and works in two ways: phentermine acts to lower the appetite and reduce food intake and topiramate can help you feel more full.
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Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Qsymia only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.