Prescription Weight Loss Drugs

Eating less and moving more are the basics of weight loss that lasts. For some people, prescription weight loss drugs may help.

You'll still need to focus on diet and exercise while taking these drugs, and they're not for everyone.

Doctors usually prescribe them only if your BMI is 30 or higher, or if it's at least 27 and you have a condition that may be related to your weight, like type 2 diabetes or high blood pressure.

Here's what you should know about the most common prescription weight loss drugs: orlistat, Belviq, Contrave, Saxenda, phentermine, and Qsymia.

Before you get a weight loss drug prescription, tell your doctor about your medical history. That includes any allergies or other conditions you have; medicines or supplements you take (even if they're herbal or natural); and whether you're pregnant, breastfeeding, or planning to get pregnant soon.

weight loss medicines

Orlistat (Xenical)

How it works: Blocks your body from absorbing about a third of the fat you eat.

When a doctor prescribes orlistat, it's called Xenical. If you get it without a prescription, it's called Alli, which has half of Xenical's dose.

Approved for long-term use? Yes.

Side effects include abdominal cramping, passing gas, leaking oily stool, having more bowel movements, and not being able to control bowel movements.

These side effects are generally mild and temporary. But they may get worse if you eat high-fat foods.

Rare cases of severe liver injury have been reported in people taking orlistat, but it's not certain that the drug caused those problems.

What else you should know: You should be on a low-fat diet (less than 30% of your daily calories from fat) before taking orlistat.

Also, take a multivitamin at least 2 hours before or after taking orlistat, because the drug temporarily makes it harder for your body to absorb vitamins A, D, E, and K.

Orlistat is the only drug of its kind that's approved in the U.S. All other prescription weight loss drugs curb your appetite, including the following.

Belviq

How it works: Curbs your appetite.

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Approved for long-term use? Yes.

Side effects: The most common side effects in people who don't have diabetes are headache, dizziness, nausea, fatigue, dry mouth, and constipation.

The most common side effects in those who have diabetes are low blood sugar (hypoglycemia), headache, back pain, cough, and fatigue.

People taking some depression medications with Belviq need to be monitored very closely for a rare but serious reaction that includes fever and confusion.

Women who are pregnant or planning to get pregnant shouldn't take Belviq.

What else you should know: If you don't lose 5% of your weight after 12 weeks of taking Belviq, you should stop taking it, because it's unlikely to work for you, the FDA says.

Contrave

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.

Saxenda

How it works: Saxenda is a higher dose of the type 2 diabetes drug Victoza. It mimics an intestinal hormone that tells the brain your stomach is full.

Approved for long-term use? Yes.

Side effects: Nausea, vomiting, diarrhea, constipation, low blood pressure, and increased appetite. Serious side effects can include raised heart rate, pancreatitis, gallbladder disease, kidney problems, and suicidal thoughts.

What else you should know: If you don't lose 4% of your weight after 16 weeks of taking Saxenda, you should stop taking it, because it's unlikely to work for you, the FDA says.

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Phentermine

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.

Qsymia

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.

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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.

WebMD Medical Reference Reviewed by Melinda Ratini, DO, MS on April 04, 2016

Sources

SOURCES:

National Institute of Diabetes and Digestive and Kidney Disease: "Prescription Medications for the Treatment of Obesity."

FDA: "FDA Drug Safety Communication: Completed Safety Review of Xenical/Alli (orlistat) and Severe Liver Injury" and "Medications Target Long-Term Weight Control."

MedlinePlus: "Phentermine."

News release, FDA.

MedlinePlus.

 

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