WIN Weight-control Information Network

U.S. DEPARTMENT

OF HEALTH AND

HUMAN SERVICES

besity is a chronic disease that affects many people and often

requires long-term treatment to promote and sustain weight

loss. As in other chronic conditions, such as diabetes or high blood

pressure, long-term use of prescription medications may be

appropriate for some people.

Prescription weight-loss medications should be used only by patients

who are at increased medical risk because of their weight. They

should not be used for “cosmetic” weight loss. Prescription weightloss drugs are approved only for those with a body mass index

(BMI) of 30 and above, or 27 and above if they have obesity-related

conditions, such as high blood pressure, dyslipidemia (abnormal

amounts of fat in the blood), or type 2 diabetes. BMI is a measure

of weight in relation to height. A BMI of 18.5 to 24.9 is considered

healthy. (See WIN’s brochure Weight and Waist Measurement: Tools

for Adults for more information.)

Although most side effects of prescription medications for obesity

are mild, serious complications have been reported. Also, there are

few studies lasting more than 2 years evaluating the safety or

effectiveness of weight-loss medications. Weight-loss medications

should always be combined with a program of healthy eating and

regular physical activity.

The information in this fact sheet may help you decide if and what

kind of weight-loss medication may help you in your efforts to reach

and stay at a healthy weight. It does not replace medical advice from

your doctor.

Medications That Promote Weight Loss

■ Appetite suppressants. Most available weight-loss medications

approved by the Food and Drug Administration (FDA) are

appetite-suppressant medications. Appetite-suppressant medicaPrescription

Medications for the

Treatment of Obesity

Weight-loss

medications

should always be

combined with a

program of healthy

eating and regular

physical activity.

O
2

tions promote weight loss by decreasing appetite or increasing the

feeling of being full. These medications make you feel less hungry

by increasing one or more brain chemicals that affect mood and

appetite. Phentermine and sibutramine are the most commonly

prescribed appetite-suppressants in the U.S.

NOTE: Amphetamines are a type of appetite suppressant. However,

amphetamines are not recommended for use in the treatment of

obesity due to their strong potential for abuse and dependence.

■ Lipase inhibitors. One drug works in a different way. Orlistat

works by reducing the body’s ability to absorb dietary fat by about

one third. It does this by blocking the enzyme lipase, which is

responsible for breaking down dietary fat. When fat is not broken

down, the body cannot absorb it, so fewer calories are taken in.

■ Other medications (not FDA-approved for the treatment of

obesity).

Drugs to treat depression. Some antidepressant medications have

been studied as appetite-suppressant medications. While these

medications are FDA-approved for the treatment of depression,

their use in weight loss is an “off-label” use (see box). Studies of

these medications generally have found that patients lose modest

amounts of weight for up to 6 months, and tend to regain weight

while they are still on the drug. One exception is bupropion. In one

study, patients taking buproprion maintained weight loss for up to

1 year.

What is “off-label” use?

Although the FDA regulates how a medication can be advertised or

promoted by the manufacturer, these regulations do not restrict a

doctor’s ability to prescribe the medication for different conditions,

in different doses, or for different lengths of time. The practice of

prescribing medication for periods of time or for conditions not FDAapproved is known as “off-label” use. While such use often occurs

in the treatment of many conditions, you should feel comfortable

about asking your doctor if he or she is using a medication or

combination of medications in a manner that is not approved by the

FDA

Until more

information on

their safety or

effectiveness is

available, using

combinations of

medications for

weight loss is not

recommended,

except as part of

a research study.
3

Drugs to treat seizures. Two medications used to treat seizures,

topiramate and zonisamide, have been shown to cause weight loss.

Whether these drugs will be useful in treating obesity is being

studied.

Drugs to treat diabetes. The diabetes medication metformin may

promote small amounts of weight loss in people with obesity and

type 2 diabetes. How this medication promotes weight loss is not

clear, although research has shown reduced hunger and food

intake in people taking the drug.

Drug combinations. The combined drug treatment using

fenfluramine and phentermine (“fen/phen”) is no longer available

due to the withdrawal of fenfluramine from the market after some

patients experienced serious heart and lung disorders. (See page 5

for more information.) Little information is available about the

safety or effectiveness of other drug combinations for weight loss,

including fluoxetine/phentermine, phendimetrazine/phentermine,

orlistat/sibutramine, herbal combinations, or others. Until more

information on their safety or effectiveness is available, using

combinations of medications for weight loss is not recommended,

except as part of a research study.

Over the short

term, weight loss

in individuals who

are obese may

reduce a number

of health risks.

Table 1. FDA-Approved Prescription Weight-loss Medications

Generic Name Trade Name(s) Drug Type FDA Approval Date

Generic Name Trade Name(s) Drug Type FDA Approval Date
4

Drugs in development. Many medications are being tested as

potential treatments for obesity. Two are being studied with patients in clinical trials. Rimonabant affects brain chemicals and

ciliary neurotrophic factor affects hormones to control appetite.

Currently, these medications are only available in clinical trials.

Clinical trials are research studies with human volunteers so that

specific health questions can be answered.

Potential Benefits of Medication Treatment

People respond differently to weight-loss medications, and some

people experience more weight loss than others. Weight-loss

medications lead to an average weight loss of 5 to 22 pounds more

than what you might lose with non-drug obesity treatments. Some

patients using medication lose more than 10 percent of their starting

body weight. Maximum weight loss usually occurs within 6 months

of starting medication treatment. Weight then tends to level off or

increase during the remainder of treatment.

Over the short term, weight loss in individuals who are obese may

reduce a number of health risks. Studies have found that weight loss

with some medications improves blood pressure, blood cholesterol,

triglycerides (fats), and insulin resistance (the body’s inability to use

blood sugar). New research suggests that long-term use of weightloss medications may help individuals keep off the weight they have

lost. However, more studies are needed to determine the long-term

effects of weight-loss medications on weight and health.

Potential Risks and Concerns

When considering long-term weight-loss medication treatment for

obesity, you should consider the following areas of concern and

potential risks.

■ Potential for abuse or dependence. Currently, all prescription

medications to treat obesity except orlistat are controlled substances, meaning doctors need to follow certain restrictions when

prescribing them. Although abuse and dependence are not common with non-amphetamine appetite-suppressant medications,

doctors should be cautious when they prescribe these medications

for patients with a history of alcohol or other drug abuse.

■ Development of tolerance. Most studies of weight-loss medications show that a patient’s weight tends to level off after 6 months

while still on medication. Although some patients and doctors may

be concerned that this shows tolerance to the medications, the

Because weightloss medications

are used to treat

a condition that

affects millions

of people, many

of whom are

basically healthy,

the possibility

that side effects

may outweigh

benefits is of

great concern.
5

leveling off may mean that the medication has reached its limit of

effectiveness. Based on the currently available studies, it is not

clear if weight gain with continuing treatment is due to drug

tolerance. It is clear, however, that weight gain would be much

faster if the patient stopped taking the drug.

■ Reluctance to view obesity as a chronic disease. Obesity often is

viewed as the result of a lack of willpower, weakness, or a lifestyle

“choice”—the choice to overeat and underexercise. Such social

views on obesity should not prevent patients from seeking medical

treatment to prevent health risks that can cause serious illness and

death. Weight-loss medications, however, are not “magic bullets”

or a one-shot fix for this chronic disease. They should be combined with a healthy eating plan and increased physical activity.

■ Side effects. Because weight-loss medications are used to treat a

condition that affects millions of people, many of whom are

basically healthy, the possibility that side effects may outweigh

benefits is of great concern. Most side effects of these medications

are mild and usually improve with continued treatment. Rarely,

serious and even fatal outcomes have been reported. Side effects of

medications are explained below.

Orlistat. Some side effects of orlistat include cramping, intestinal

discomfort, passing gas, diarrhea, and leakage of oily stool. These

side effects are generally mild and temporary, but may be worsened by eating foods that are high in fat. Also, because orlistat

reduces the absorption of some vitamins, patients should take a

multivitamin at least 2 hours before or after taking orlistat.

Sibutramine. The main side effects of sibutramine are increases in

blood pressure and heart rate, which are usually small but may be

of concern in some patients. Other side effects include headache,

dry mouth, constipation, and insomnia. People with poorly controlled high blood pressure, heart disease, irregular heartbeat, or

history of stroke should not take sibutramine, and all patients

taking the medication should have their blood pressure monitored

on a regular basis.

Other appetite suppressants. Phentermine, phendimetrazine, and

diethylpropion may cause symptoms of sleeplessness, nervousness, and euphoria (feeling of well-being). People with heart

disease, high blood pressure, an overactive thyroid gland, or

glaucoma should not use these drugs.

Two appetite-suppressant medications, fenfluramine and

dexfenfluramine, were withdrawn from the market in 1997.

These drugs, used alone and in combination with phentermine

Ask your doctor

about ways you

can improve your

eating plan and

become more

physically active.
(“fen/phen”) were linked to the development of valvular heart

disease and primary pulmonary hypertension (PPH), a rare but

potentially fatal disorder that affects the blood vessels in the

lungs. There have been only a few case reports of PPH in patients

taking phentermine alone, but the possibility that phentermine use

is associated with PPH cannot be ruled out.

Commonly Asked Questions About Weight-Loss

Medications

Q: Can medications replace physical activity or changes in

eating habits as a way to lose weight?

A: No. Studies show that weight-loss medications work best when

combined with a weight-control program that helps you improve

your eating and physical activity habits. Ask your doctor about ways

you can improve your eating plan and become more physically

active.

Q: What medical conditions or medications might influence my

decision to take a weight-loss drug?

A: Let your doctor know if you have any of the following medical

conditions, which may affect which weight-loss drugs you can take,

if any:

■ Pregnancy or breast-feeding

■ History of drug or alcohol abuse

■ History of anorexia or bulimia

■ History of depression or manic depressive disorder

■ Use of monoamine oxidase (MAO) inhibitors or antidepressant

medications

■ Migraine headaches requiring medication

■ Glaucoma

■ Diabetes

■ Heart disease or heart condition, such as an irregular heart beat

■ High blood pressure

■ Plan to have surgery that requires general anesthesia.

Because obesity is

a chronic disease,

any treatment,

whether drug or

non-drug, may

need to be

continued for

years, and

perhaps a lifetime,

to improve health

and maintain a

healthy weight.

6
Q: How long will I need to take weight-loss medications to treat

obesity?

A: The answer depends upon whether the medication helps you to

lose and maintain weight and whether you have any side effects.

Because obesity is a chronic disease, any treatment, whether drug or

non-drug, may need to be continued for years, and perhaps a

lifetime, to improve health and maintain a healthy weight. However,

like many other types of drugs, there is still little information on how

safe and effective weight-loss medications are for many years of use.

At least one study has shown that intermittent use (one month on

medication and one month off medication) may help some people

lose and maintain weight, but more research is needed.

Q: Will I regain some weight after I stop taking weight-loss

medications?

A: Probably. Most studies show that the majority of patients who

stop taking weight-loss medications regain the weight they lost.

Maintaining healthy eating and physical activity habits may help

you regain less weight.

Q: Can children or teens use weight-loss medications?

A: Orlistat is currently approved for use in teens age 12 or above.

Other weight-loss medications are not approved for use in children

under the age of 16, although studies in children and teens are

ongoing.

Q: Will insurance cover the cost of weight-loss medication?

A: Many insurance companies currently will not pay for weight-loss

prescriptions, but this is changing as insurers begin to recognize

obesity as a chronic disease. Contact your insurance company to find

out if prescription weight-loss medication is covered under your

plan. The cost of one month of a prescription can cost about 60

dollars a month to more than twice this amount. Ask a staff member

at your pharmacy the cost of a 1-month supply of the medication

you are considering taking.

■ ■ ■

Most patients should not expect to reach an “ideal” body weight

using currently available medications. However, even a modest

weight loss of 5 to 10 percent of your starting body weight can

improve your health. Together, you and your doctor can make an

informed choice as to whether medication can be a useful part of

your weight-control program.

Together, you

and your doctor

can make an

informed choice

as to whether

medication can

be a useful part

of your weightcontrol program.

7
NIH Publication No. 04-4191

November 2004

Weight-control

Information

Network

1 WIN WAY

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This publication is not copyrighted. WIN

encourages users of this fact sheet to duplicate

and distribute as many copies as desired.

This fact sheet is also available at

www.win.niddk.nih.gov

National Institute of Diabetes and

Digestive and Kidney Diseases

The Weight-control Information

Network (WIN) is a national

information service of the National

Institute of Diabetes and Digestive

and Kidney Diseases of the National

Institutes of Health, which is the

Federal Government’s lead agency

responsible for biomedical research

on nutrition and obesity. Authorized

by Congress (Public Law 103-43),

WIN provides the general public,

health professionals, the media, and

Congress with up-to-date, sciencebased health information on weight

control, obesity, physical activity,

and related nutritional issues.

Publications produced by WIN are

reviewed by both NIDDK scientists

and outside experts. This fact sheet

was also reviewed by Myrlene

Staten, Ph.D., Senior Advisor,

Diabetes Translational Research;

Division of Diabetes, Endocrinology,

and Metabolic Diseases; NIDDK.