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Prescription Medications to Treat Overweight and Obesity

What are overweight and obesity?

Health care providers use the Body Mass Index (BMI), which is a measure of your weight in relation to your height, to define overweight and obesity. People who have a BMI between 25 and 30 are considered overweight. Obesity is defined as having a BMI of 30 or greater. You can calculate your BMI to learn if you are overweight or obese. Being overweight or obese may increase the risk of health problems. Your health care provider can assess your individual risk due to your weight.

Obesity is a chronic condition that affects more than one in three adults in the United States. Another one in three adults is overweight. If you are struggling with your weight, you may find that a healthy eating plan and regular physical activity help you lose weight and keep it off over the long term. If these lifestyle changes are not enough to help you lose weight or maintain your weight loss, your doctor may prescribe medications as part of your weight-control program.

How do weight-loss medications work?

Prescription medications to treat overweight and obesity work in different ways. For example, some medications may help you feel less hungry or full sooner. Other medications may make it harder for your body to absorb fat from the foods you eat.

Who might benefit from weight-loss medications?

Weight-loss medications are meant to help people who may have health problems related to overweight or obesity. Before prescribing a weight-loss medication, your doctor also will consider

  • the likely benefits of weight loss
  • the medication’s possible side effects
  • your current health issues and other medications
  • your family's medical history
  • cost

Health care professionals often use BMI to help decide who might benefit from weight-loss medications. Your doctor may prescribe a medication to treat your overweight or obesity if you are an adult with

Weight-loss medications aren’t for everyone with a high BMI. Some people who are overweight or obese may lose weight with a lifestyle program that helps them change their behaviors and improve their eating and physical activity habits. A lifestyle program may also address other factors that affect weight gain, such as eating triggers and not getting enough sleep.

Can children or teenagers take weight-loss medications?

The U.S. Food and Drug Administration (FDA) has approved most weight-loss medications only for adults. The prescription medication orlistat (Xenical) is FDA-approved for children ages 12 and older.

Can medications replace physical activity and healthy eating habits as a way to lose weight?

Medications don’t replace physical activity or healthy eating habits as a way to lose weight. Studies show that weight-loss medications work best when combined with a lifestyle program. Ask your doctor or other health care professional about lifestyle treatment programs for weight management that will work for you.

Two women walking down a paved road with earbuds in their ears.
Weight-loss medications don’t replace physical activity and healthy eating habits.

What are the benefits of using prescription medications to lose weight?

When combined with changes to behavior, including eating and physical activity habits, prescription medications may help some people lose weight. On average, people who take prescription medications as part of a lifestyle program lose between 3 and 9 percent more of their starting body weight than people in a lifestyle program who do not take medication. Research shows that some people taking prescription weight-loss medications lose 10 percent or more of their starting weight.1 Results vary by medication and by person.

Weight loss of 5 to 10 percent of your starting body weight may help improve your health by lowering blood sugar, blood pressure, and triglycerides. Losing weight also can improve some other health problems related to overweight and obesity, such as joint pain or sleep apnea. Most weight loss takes place within the first 6 months of starting the medication.

What are the concerns with using prescription medications to lose weight?

Experts are concerned that, in some cases, the side effects of prescription medications to treat overweight and obesity may outweigh the benefits. For this reason, you should never take a weight-loss medication only to improve the way you look. In the past, some weight-loss medications were linked to serious health problems. For example, the FDA recalled fenfluramine and dexfenfluramine (part of the “fen-phen” combination) in 1997 because of concerns related to heart valve problems.

Possible side effects vary by medication and how it acts on your body. Most side effects are mild and most often improve if you continue to take the medication. Rarely, serious side effects can occur.

Tips for Taking Weight-loss Medication

  • Follow your doctor's instructions about weight-loss medications.
  • Buy your medication from a pharmacy or web distributor approved by your doctor.
  • Take weight-loss medication to support your healthy eating and physical activity program.
  • Know the side effects and warnings for taking any medication.
  • Ask your doctor if you should stop taking your medication if you are not losing weight after 12 weeks.
  • Discuss other medications, including supplements and vitamins, you are taking with your doctor when considering weight-loss medications.
  • Avoid taking weight-loss medications during pregnancy or if you are planning a pregnancy.

Which weight-loss medication might work for me?

Choosing a medication to treat overweight or obesity is a decision between you and your doctor. Important factors to consider include

  • the likely benefits of weight loss
  • the medication’s possible side effects
  • your current health issues and other medications
  • your family’s medical history
  • cost
Doctor in lab coat weighing obese patient in blue shirt.
Talk with your doctor about which weight-loss medication might be right for you.

How long will I need to take weight-loss medication?

How long you will need to take weight-loss medication depends on whether the drug helps you lose and maintain weight and whether you have any side effects. If you have lost enough weight to improve your health and are not having serious side effects, your doctor may advise that you stay on the medication indefinitely. If you do not lose at least 5 percent of your starting weight after 12 weeks on the full dose of your medication, your doctor will probably advise you to stop taking it. He or she may change your treatment plan or consider using a different weight-loss medication. Your doctor also may have you try different lifestyle, physical activity, or eating programs; change your other medications that cause weight gain; or refer you to a bariatric surgeon to see if weight-loss surgery might be an option for you.

Because obesity is a chronic condition, you may need to continue changes to your eating and physical activity habits and other behaviors for years—or even a lifetime—to improve your health and maintain a healthy weight.

Will I regain some weight after I stop taking weight-loss medication?

You will probably regain some weight after you stop taking weight-loss medication. Developing and maintaining healthy eating habits and increasing physical activity may help you regain less weight or keep it off. Federal physical activity guidelines recommend at least 150 minutes of physical activity per week for adults—that’s about 30 minutes a day most days of the week. You may need to do more to reach or maintain your weight-loss goal.

Will insurance cover the cost of weight-loss medication?

Some, but not all, insurance plans cover medications that treat overweight and obesity. Contact your insurance provider to find out if your plan covers these medications.

What medications are available to treat overweight and obesity?

The table below lists FDA-approved prescription medications for weight loss. The FDA has approved five of these drugs—orlistat (Xenical, Alli), lorcaserin (Belviq), phentermine-topiramate (Qsymia), naltrexone-bupropion (Contrave), and liraglutide (Saxenda)—for long-term use. You can keep taking these drugs as long as you are benefiting from treatment and not having unpleasant side-effects.

Some weight-loss medications that curb appetite are approved by the FDA only for short-term use, or up to 12 weeks. Although some doctors prescribe them for longer periods of time, not many research studies have looked at how safe and effective they are for long-term use.

Pregnant women should never take weight-loss medications. Women who are planning to get pregnant also should avoid these medications, as some of them may harm a fetus.

Prescription Medications Approved for Overweight and Obesity Treatment

Weight-loss medication Approved for How it works Common side effects Warnings
Orlistat (Xenical)

Available in lower dose without prescription (Alli)
Adults and children ages 12 and older Works in your gut to reduce the amount of fat your body absorbs from the food you eat
  • diarrhea
  • gas
  • leakage of oily stools
  • stomach pain
Rare cases of severe liver injury have been reported. Avoid taking with cyclosporine. Take a multivitamin pill daily to make sure you get enough of certain vitamins that your body may not absorb from the food you eat.
Lorcaserin (Belviq) Adults Acts on the serotonin receptors in your brain. May help you feel full after eating smaller amounts of food.
  • constipation
  • cough
  • dizziness
  • dry mouth
  • feeling tired
  • headaches
  • nausea
Tell your doctor if you take antidepressants or migraine medications, since some of these can cause problems when taken together.
Phentermine-topiramate (Qsymia) Adults A mix of two medications: phentermine, which lessens your appetite, and topiramate, which is used to treat seizures or migraine headaches. May make you less hungry or feel full sooner.
  • constipation
  • dizziness
  • dry mouth
  • taste changes, especially with carbonated beverages
  • tingling of your hands and feet
  • trouble sleeping
Don’t use if you have glaucoma or hyperthyroidism. Tell your doctor if you have had a heart attack or stroke, abnormal heart rhythm, kidney disease, or mood problems.

MAY LEAD TO BIRTH DEFECTS. DO NOT TAKE QSYMIA IF YOU ARE PREGNANT OR PLANNING A PREGNANCY. Do not take if you are breastfeeding.
Naltrexone-bupropion (Contrave) Adults A mix of two medications: naltrexone, which is used to treat alcohol and drug dependence, and bupropion, which is used to treat depression or help people quit smoking. May make you feel less hungry or full sooner.
  • constipation
  • diarrhea
  • dizziness
  • dry mouth
  • headache
  • increased blood pressure
  • increased heart rate
  • insomnia
  • liver damage
  • nausea
  • vomiting
Do not use if you have uncontrolled high blood pressure, seizures or a history of anorexia or bulimia nervosa. Do not use if you are dependent on opioid pain medications or withdrawing from drugs or alcohol. Do not use if you are taking bupropion (Wellbutrin, Zyban).

MAY INCREASE SUICIDAL THOUGHTS OR ACTIONS.
Liraglutide (Saxenda)

Available by injection only
Adults May make you feel less hungry or full sooner. At a lower dose under a different name, Victoza, FDA-approved to treat type 2 diabetes.
  • nausea
  • diarrhea
  • constipation
  • abdominal pain
  • headache
  • raised pulse
May increase the chance of developing pancreatitis. Has been found to cause a rare type of thyroid tumor in animals.
Other medications that curb your desire to eat include
  • phentermine
  • benzphetamine
  • diethylpropion
  • phendimetrazine
Adults Increase chemicals in your brain to make you feel you are not hungry or that you are full.

Note: FDA-approved only for short-term use—up to 12 weeks
  • dry mouth
  • constipation
  • difficulty sleeping
  • dizziness
  • feeling nervous
  • feeling restless
  • headache
  • raised blood pressure
  • raised pulse
Do not use if you have heart disease, uncontrolled high blood pressure, hyperthyroidism, or glaucoma. Tell your doctor if you have severe anxiety or other mental health problems.

How do doctors use prescription medications “off-label” to treat overweight and obesity?

Sometimes doctors use medications in a way that’s different from what the FDA has approved, known as “off-label” use. By choosing an off-label medication to treat overweight and obesity, your doctor may prescribe

  • a drug approved for treating a different medical problem
  • two or more drugs at the same time
  • a drug for a longer period of time than approved by the FDA

You should feel comfortable asking your doctor if he or she is prescribing a medication that is not approved just for treating overweight and obesity. Before using a medication, learn all you need to know about it.

What other medications for weight loss may be available in the future?

Researchers are currently studying several new medications and combinations of medications in animals and people. Researchers are working to identify safer and more effective medications to help people who are overweight or obese lose weight and maintain a healthy weight for a long time.

Future drugs may use new strategies, such as to

  • combine drugs that affect appetite and those that affect addiction (or craving)
  • stimulate gut hormones that reduce appetite
  • shrink the blood vessels that feed fat cells in the body, thereby preventing them from growing
  • target genes that affect body weight
  • change bacteria in the gut to control weight

References

July 2016
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This content is provided as a service of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), part of the National Institutes of Health. The NIDDK translates and disseminates research findings through its clearinghouses and education programs to increase knowledge and understanding about health and disease among patients, health professionals, and the public. Content produced by the NIDDK is carefully reviewed by NIDDK scientists and other experts.

The NIDDK would like to thank:
Kishore Gadde, M.D., Pennington Biomedical Research Center