Generic Name: phentermine and topiramate (FEN ter meen and toe PIR a mate)
Brand Name: Qsymia
Medically reviewed by Sophia Entringer, PharmD. Last updated on Jan 7, 2021.
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 treat obesity. This medicine is sometimes used to treat obesity that may be related to diabetes, high cholesterol, or high blood pressure.
Qsymia will not treat any these underlying conditions. Keep using any other medicines your doctor has prescribed to treat these conditions.
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:
overactive thyroid; or
if you are pregnant or may become pregnant.
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 18 years old.
To make sure Qsymia is safe for you, tell your doctor if you have:
heart problems, high blood pressure;
a heart attack or stroke;
diabetes (weight loss may cause low blood sugar);
metabolic acidosis (too much acid in your blood);
kidney disease, kidney stones, or dialysis;
mood problems, depression, or suicidal thoughts or actions;
a seizure; or
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.
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.
Your doctor may change your dose or tell you to stop taking this medicine if you have not lost a certain amount of weight during the first 12 weeks. Follow your doctor's dosing instructions very carefully. You must also follow a low-calorie diet.
Do not stop using Qsymia suddenly or you could have a seizure (convulsions). Follow your doctor's instructions about tapering your dose.
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.
Qsymia 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.
-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, treatment discontinuation or dose escalation should be considered as it is unlikely the patient will achieve and sustain clinically meaningful weight loss at this dose.
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.
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 should I avoid while taking Qsymia?
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; difficulty breathing; swelling of your face, lips, tongue, or throat.
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:
unusual changes in mood or behavior;
confusion, trouble concentrating, problems with speech or memory;
fast or pounding heartbeats while you are resting;
signs of a kidney stone - severe pain in your side or lower back, painful or difficult urination; or
signs of too much acid in your blood - loss of appetite, tiredness, thinking problems, irregular heartbeats.
Common Qsymia side effects may include:
numbness or tingly feeling;
sleep problems (insomnia); or
dry mouth, changes in your sense of taste.
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:
a diuretic or "water pill";
insulin or oral diabetes medicine; or
medicines that impair or decrease your thinking, concentration, or muscle coordination.
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.
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.
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