Qsymia side effects and how to avoid them

Qsymia is an FDA (U.S. Food and Drug Administration) approved medication manufactured by Vivus, Inc. It is used with a reduced-calorie diet and an increase in physical activity for chronic weight management in adults with a body mass index (BMI) of 30 kg/m2 or more (obese), or 27 kg/m2 or more (overweight) with at least one weight-related comorbidity such as hypertension (high blood pressure), type 2 diabetes mellitus, or dyslipidemia (high cholesterol). While Qsymia is generally well tolerated, there are some potential side effects that people should be aware of. The most common side effects of Qsymia include difficulty sleeping. Less common, but more serious side effects, can include suicidal thoughts or behavior.

Learn more about the side effects of Qsymia and what you can do to avoid them.

What is Qsymia (phentermine and topiramate)?

Qsymia contains phentermine, an appetite suppressant belonging to a class of drugs called sympathomimetic amines, and topiramate, an anticonvulsant. As Qsymia contains phentermine, a Schedule IV drug, it too is controlled under Schedule IV of the Controlled Substances Act. Qsymia is only available under a special program called the Qsymia REMS program.

Qsymia dosage

Qsymia is available in capsule form, in the following doses: phentermine/topiramate extended-release 3.75 mg/23 mg, 7.5 mg/46 mg, 11.25 mg/69 mg, or 15 mg/92 mg.

The recommended dose of Qsymia is 3.75 mg/23 mg daily for 14 days, then increased to 7.5 mg/46 mg daily. Weight loss should be checked after 12 weeks. If a patient has not lost a minimum of 3% of baseline body weight, stop treatment or reduce the dose as it is unlikely the patient will achieve and maintain clinically meaningful weight loss at this dose. If you miss a dose of Qsymia, skip the missed dose and take your next dose at the normal time. Do not double your dose to catch up.

You are advised to read the medication guide provided with this medicine for the drug information and patient information, and always speak with your healthcare provider for medical advice about any changes to your dose so they can monitor and evaluate your condition.

Qsymia side effects

The most common side effects of Qsymia in clinical trials compared to placebo include:

  • Paraesthesia
  • Skin reactions
  • Back pain
  • Dizziness
  • Dysgeusia
  • Trouble sleeping
  • Drowsiness
  • Constipation
  • Dry mouth

In rare instances, Qsymia can cause more serious side effects. These can include:

  • Fetal Toxicity – females of reproductive potential should obtain a negative pregnancy test before treatment and monthly after that, and use effective contraception
  • Increase in heart rate
  • Suicidal thoughts or ideation
  • Acute myopia and secondary angle-closure glaucoma
  • Mood changes and sleep disorders
  • Cognitive impairment
  • Metabolic acidosis – loss of appetite, tiredness, thinking problems, irregular heartbeats
  • Elevated creatinine
  • Decreased sweating and increased body temperature
  • Sudden changes in vision such as decreased vision, blurred vision, eye pain/redness

Your doctor will assess the benefits of using Qsymia against your risk of side effects. Patients are encouraged to report negative side effects or adverse reactions of Qsymia to the FDA. Visit www.fda.gov/medwatch, or call 1-800-FDA-1088.

What are the long-term side effects of Qsymia?

Qsymia may cause serious pulmonary hypertension, and heart valve problems. The risk of this occurring increases with long-term use and if used with other appetite suppressants.

Does Qsymia cause hair loss?

Topiramate, one of the active ingredients in Qsymia has been seen to cause hair loss. This is not a common side effect and has only been reported in 1% to 4% of children.

How much weight do you lose on Qsymia?

Patients lost on average 15 lbs after taking Qsymia for around 3 months. After using Qsymia for around 1 year, patients lost on average 24 lbs.

Do the side effects of Qsymia go away?

Some side effects may disappear on their own during treatment and may not need medical attention. This usually occurs as your body becomes used to Qsymia.

How does Qsymia make you feel?

Side effects of Qsymia may include tingling in your hands and feet, feeling dizzy, a change in taste in your mouth, difficulty sleeping, constipation, and dry mouth. Qsymia may also increase your heart rate.

Qsymia drug interactions

Qsymia can interact with other medications. These include:

  • Birth control pills
  • CNS depressants including alcohol
  • Non-potassium sparing diuretics
  • Valproic acid used to control seizures
  • Carbonic anhydrase inhibitors such as acetazolamide, methazolamide, or zonisamide

This list is not exhaustive and other drugs may interact with Qsymia. Tell your healthcare provider about all the medicines you take, including prescription drugs and over-the-counter medicines, vitamins, and herbal supplements.

Qsymia warnings & precautions

You should not use Qsymia if you:

  • Are allergic to the active ingredients phentermine or topiramate
  • Have had an allergic reaction to any of the other ingredients in Qsymia
  • Have glaucoma
  • Have thyroid problems (hyperthyroidism)
  • Have taken monoamine oxidase inhibitors (MAOIs) within 14 days
  • Have known hypersensitivity or idiosyncrasy to sympathomimetic amines
  • Are pregnant or are planning to become pregnant – may cause birth defects (cleft lip/cleft palate) or harm an unborn baby. Discuss the use of birth control with your doctor

Talk to your doctor before using Qsymia if you:

  • Are taking any of the medications that could interact with Qsymia
  • Have heart problems, or high blood pressure
  • Have heart disease, have had a heart attack or stroke
  • Have diabetes (weight loss may cause low blood sugar)
  • Have metabolic acidosis
  • Have osteomalacia, osteopenia, or osteoporosis
  • Have kidney disease, kidney stones, or dialysis
  • Have liver disease
  • Have depression, suicidal thoughts, or other mental health problems
  • Suffer from seizures
  • Are breastfeeding or are planning to breastfeed – This medication can pass into your breast milk

Other warnings you should know about

Stopping treatment with Qsymia suddenly can cause seizures. You are advised to speak to your healthcare provider before you stop taking Qsymia.

How to avoid Qsymia side effects

The best way to avoid side effects is to take Qsymia as directed by your doctor. Follow your doctor’s instructions carefully and do not take more or less than prescribed.

If you experience any side effects, talk to your doctor or pharmacist. They may be able to recommend ways to help reduce or prevent some of the side effects.

1. Stick to the recommended dosage

Take your prescribed dose of Qsymia that has been recommended by your healthcare professional. Do not take more or less than prescribed.

2. Monitor your blood sugar levels

If you have diabetes, it is important to monitor your blood sugar levels closely while taking Qsymia. Check your blood sugar levels as directed by your doctor and report any changes to your doctor immediately.

3. Drink plenty of fluids

Drink eight to 10 glasses of water or fluids every day to help prevent dehydration, which can make side effects worse.

4. Avoid alcohol

Avoid drinking alcohol while taking Qsymia as it can increase your risk of serious side effects, such as central nervous system depression, and an increase in your risk of falls.

5. Don’t skip meals

Eating regular meals and snacks will help to prevent low blood sugar levels (hypoglycemia).

6. Check your feet

If you have diabetes, check your feet regularly for any cuts, sores, or redness. Tell your doctor if you experience any problems with your feet while taking Qsymia.

7. Know the signs and symptoms of Qsymia side effects

Signs and symptoms of side effects include difficulty sleeping and drowsiness. If you experience any of these symptoms speak to your doctor for medical advice.

8. Tell your doctor about all medications you’re taking

Be sure to tell your doctor about all other medications you’re taking, including over-the-counter drugs, vitamins, and herbal supplements, as they can interact with Qsymia.

9. Get regular medical check ups

It is important to get regular medical check ups and monitor your medical conditions. Your doctor will monitor your side effects and may adjust your dose of Qsymia as needed.

Medically reviewed

A medical professional has reviewed this article.

Jamie Winn, PharmD
Jamie Winn, PharmD

Jamie Winn, PharmD

Medical Writer & Reviewer

Jamie Winn, PharmD

Medical Writer & Reviewer

Dr. Jamie Winn received his Doctor of Pharmacy in 2002 from the University of South Carolina College of Pharmacy, Columbia, SC. Jamie is a medical reviewer for NiceRx.

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The content on this website is intended for information purposes only. It does not constitute medical advice. The information on this website should not be relied upon and is not a substitute for professional medical advice. You should always speak to your doctor regarding the risks and benefits of any treatment.
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