Prescription Weight Loss Drugs
How it works: Contrave is a combination of two FDA-approved drugs, naltrexone and bupropion, in an extended-release formula. Naltrexone is approved to treat alcohol and opioid dependence. Bupropion is approved to treat depression, seasonal affective disorder, and help people stop smoking.
Approved for long-term use? Yes.
Side effects: The most common side effects include nausea, constipation, headache, vomiting, dizziness, insomnia, dry mouth, and diarrhea. Contrave has a boxed warning about the increased risk of suicidal thoughts and behaviors associated with bupropion. The warning also notes that serious neuropsychiatric issues linked to bupropion have been reported. Contrave can cause seizures and must not be used in patients who have seizure disorders. The drug can also increase blood pressure and heart rate.
What else you should know: If you don't lose 5% of your weight after 12 weeks of taking Contrave, you should stop taking it, because it's unlikely to work for you, the FDA says.
How it works: Curbs your appetite.
Your doctor may prescribe this under the names Adipex or Suprenza.
Approved for long-term use? No. It's approved for short-term use (a few weeks) only.
Side effects can be serious, such as raising your blood pressure or causing heart palpitations, restlessness, dizziness, tremor, insomnia, shortness of breath, chest pain, and trouble doing activities you've been able to do.
Phentermine may make you drowsy, hampering your ability to drive or operate machinery. As with some other appetite suppressants, there's a risk of becoming dependent upon the drug.
Less serious side effects include dry mouth, unpleasant taste, diarrhea, constipation, and vomiting.
Don't take it late in the evening, as it may cause insomnia.
If you take insulin for diabetes, let your doctor know before you take phentermine, as you may need to adjust your insulin dose.
You should not take phentermine if you have a history of heart disease, stroke, congestive heart failure, or uncontrolled high blood pressure. You also shouldn't take it if you have glaucoma, hyperthyroidism, or a history of drug abuse, or if you are pregnant or nursing.
What else you should know: Phentermine is an amphetamine. Because of the risk of addiction or abuse, such stimulant drugs are "controlled substances," which means they need a special type of prescription.
How it works: Curbs your appetite.
Qsymia combines phentermine with the seizure/migraine drug topiramate. Topiramate causes weight loss in several ways, including helping you feel full, making foods taste less appealing, and burning more calories.
Approved for long-term use? Yes. Qsymia has much lower amounts of phentermine and topiramate than when these drugs are given alone.
Side effects: The most common side effects are tingling hands and feet, dizziness, altered sense of taste, insomnia, constipation, and dry mouth.
Serious side effects include certain birth defects (cleft lip and cleft palate), faster heart rate, suicidal thoughts or actions, and eye problems that could lead to permanent vision loss if not treated.
Women who might become pregnant should get a pregnancy test before taking Qsymia, and should use birth control and get monthly pregnancy tests while on the drug.
You also shouldn't take Qsymia if you have glaucoma, hyperthyroidism, heart disease, or stroke. Get regular checks of your heart when starting the drug or increasing the dose.
What else you should know: If you don't lose 3% of your weight after 12 weeks on Qsymia, the FDA recommends that you stop taking it or that your doctor increase your dose for the next 12 weeks -- and if that doesn't work, you should gradually stop taking it.