Obesity 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 individuals. While most side effects of prescription medications for obesity are mild, serious complications have been reported. Valvular heart disease has recently been reported to occur in association with the use of certain appetite suppressant medications. As a result of these reports, the manufacturer has voluntarily withdrawn two medications, fenfluramine (Pondimin) and dexfenfluramine (Redux) from the market. There are few long-term studies evaluating the safety or effectiveness of other currently approved appetite suppressant medications. In particular, the safety and effectiveness of combining more than one appetite suppressant medication or combining appetite suppressant medications with other medications for the purpose of weight loss is unknown. Appetite suppressant medications should be used only by patients who are at increased medical risk because of their obesity and should not be used for "cosmetic" weight loss.
| The medications most often used
in the management of obesity are commonly known as "appetite
suppressant" medications. Appetite suppressant medications
promote weight loss by decreasing appetite or increasing the
feeling of being full. These medications decrease appetite by
increasing serotonin or catecholamine--two brain chemicals that
affect mood and appetite.
Most currently available appetite suppressant medications are approved by the U.S. Food and Drug Administration (FDA) for short-term use, meaning a few weeks or months. Sibutramine is the only appetite suppresant medication approved for longer-term use in significantly obese patients, although the safety and effectiveness have not been established for use beyond one year. (See table 1 for the generic and trade names of prescription appetite suppressant medications.) While 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 approved 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. The use of more than one appetite suppressant medication at a time (combined drug treatment) is an example of an off-label use. Using currently approved appetite suppressant medication for more than a short period of time (i.e., more than "a few weeks" is also considered off-label use.
| Several appetite suppressant
medications are available to treat obesity. In general, these
medications are modestly effective, leading to an average weight
loss of 5 to 22 pounds above that expected with non-drug obesity
treatments. People respond differently to appetite suppressant
medications, and some people experience more weight loss than
others. Some obese patients using medication lose more than 10
percent of their starting body weight--an amount of weight loss
that may reduce risk factors for obesity-related diseases, such
as high blood pressure or diabetes. 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. Studies suggest that if a patient does not lose at
least 4 pounds over 4 weeks on a particular medication, then
that medication is unlikely to help the patient achieve
significant weight loss. Few studies have looked at how safe or
effective these medications are when taken for more than 1
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. Studies of these medications generally have found that patients lost modest amounts of weight for up to 6 months. However, most studies have found that patients who lost weight while taking antidepressant medications tended to regain weight while they were still on the drug treatment.
NOTE: Amphetamines and closely-related compounds are not recommended for use in the treatment of obesity due to their potential for abuse and dependence.
| Combined drug treatment using
fenfluramine and phentermine ("fen/phen") is no longer available
due to the withdrawal of fenfluramine from the market. Little
information is available about the safety or effectiveness of
other drug combinations for weight loss, including
fluoxetine/phentermine, phendimetrazine/phentermine, 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 obese individuals may reduce a number of health risks.
Studies looking at the effects of appetite suppressant
medication treatment on obesity-related health risks have found
that some agents lower blood pressure, blood cholesterol,
triglycerides (fats) and decrease insulin resistance (the body's
inability to use blood sugar) over the short term. However,
long-term studies are needed to determine if weight loss from
appetite suppressant medications can improve health.
| When considering long-term
appetite suppressant medication treatment for obesity, you
should consider the following areas of concern and potential
Some animal studies have suggested that appetite suppressant medications affecting the serotonin system, such as fenfluramine and dexfenfluramine, can lead to damage to the central nervous system. Damage to the central nervous system has not been reported in humans. Some patients have reported depression or memory loss when using some appetite suppressant medications or combinations of medications, but it is not known if these problems are caused by the medication or by other factors.
In July, 1997, researchers at the Mayo Clinic reported a case series of 24 women who developed an unusual form of disease of the heart valves. All 24 women were using the combination of fenfluramine and phentermine. The disease primarily affected the left side of the heart, and five patients required valve replacement. In cases where samples of valve tissue were obtained, there was an unusual appearance of the heart valves generally only seen with a serotonin-producing tumor called carcinoid or with excessive amounts of medications containing ergot. Following these initial case reports, the Food and Drug Administration (FDA) has continued to receive a number of reports of similar valve disease from physicians. Some of these cases involved patients who were taking fenfluramine or dexfenfluramine alone. No cases were reported in patients taking phentermine alone. In addition, physicians at five sites provided information to the FDA regarding patients, most of whom did not have signs or symptoms of valve disease. About 30% of patients at these sites showed some evidence of damaged valves, usually mild or moderate. While this was not a controlled study, and further studies are needed to determine how common the problem is in treated patients compared to the general population of overweight people, the findings were of enough concern to prompt the FDA to ask the manufacturers of fenfluramine and dexfenfluramine to voluntarily recall the drugs. This withdrawal took place on September 15th 1997. Patients who were on fenfluramine or dexfenfluramine have been advised to discontinue the drug, and to contact their physicians for an evaluation to look for signs and symptoms of heart disease and to determine the need for an echocardiogram. For more information about the withdrawal of fenfluramine and dexfenfluramine, you can access the FDA website on Questions and Answers about Withdrawal of Fenfluramine (Pondimin) and Dexfenfluramine (Redux) at http://www.fda.gov/cder/news/phen/fenphenqa2.htm. Two small studies looking at relationships between sibutramine and valvular heart disease did not find any increase in valve lesions in patients taking sibutramine compared with placebo.
| Q: Can medications replace
physical activity or changes in eating habits as a way to lose
A: No. The use of appetite suppressant medications to treat obesity should be combined with physical activity and improved diet to lose and maintain weight successfully over the long term.
A: Probably. Most studies show that the majority of patients who stop taking appetite suppressant medications regain the weight they had lost. Maintaining healthy eating and physical activity habits will increase your likelihood of keeping weight off.
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 nondrug, may need to be continued for years, and perhaps a lifetime, to improve health and maintain a healthy weight. There is little information on how safe and effective appetite suppressant medications are for more than 1 year of use.
A: There is no one correct dose for appetite suppressant medications. Your doctor will decide what works best for you based on his or her evaluation of your medical condition and response to treatment.
A: Appetite suppressant medications may be appropriate for carefully selected patients who are at significant medical risk because of their obesity. They are not recommended for use by people who are only mildly overweight unless they have health problems that are made worse by their weight. These medications should not be used only to improve appearance.
| Before choosing appetite
suppressant medication treatment for the long-term management of
obesity, you should talk to your doctor about any concerns you
may have. In addition, it is important that you discuss the
following issues with your doctor.
Your physician will look at a number of factors to determine if you are a good candidate for prescription appetite suppressant medication treatment of obesity. He or she will determine how overweight you are and where your body fat is distributed (see WIN's fact sheet Understanding Adult Obesity for further information). Your doctor may do the following:
It is important that you notify your physician if you have any of the following medical conditions:
What type of program will be provided along with the medication to help me improve my eating and physical activity habits?
Studies show that appetite suppressant medications work best when combined with a weight-management program that helps you improve your eating and physical activity habits. Ask your doctor any questions or concerns that you may have about good nutrition and physical activity.
| If you and your doctor believe
that the use of appetite suppressant medications may be helpful
for you, it is important to discuss the goals of treatment.
Improving your health and reducing your risk for disease should
be the primary goals. For most severely obese people, achieving
an "ideal body weight" is both unrealistic and unnecessary to
improve their health and reduce their risk for disease. Most
patients should not expect to reach an ideal body weight using
the currently available medications. Even a modest weight loss
of 5 to 10 percent of your starting body weight can improve your
health and reduce your risk factors for disease. Use of
appetite suppressant medications for cosmetic purposes is not
Appetite suppressant medications should be used with a program of behavioral treatment and nutritional counseling, designed to help you make long-term changes in your diet and physical activity. You should see your physician regularly so that he or she can monitor how you are responding to the medication, not only in terms of weight loss, but how it effects your overall health. Again, if you experience any serious symptoms, such as chest pains or shortness of breath, contact your doctor immediately.
Long-term use of prescription appetite suppressant medications may be helpful for carefully selected individuals, but little information is available on the safety and effectiveness of these medications when used for more than 1 year. By evaluating your risk of experiencing obesity-related health problems, you and your physician can make an informed choice as to whether medication can be a useful part of your weight-management program.
Weight-control Information Network
1 Win Way
The Weight-control Information Network (WIN) is a service of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), part of the National Institutes of Health, under the U.S. Public Health Service. Authorized by Congress (Public Law 103-43), WIN assembles and disseminates to health professionals and the public information on weight control, obesity, and nutritional disorders. WIN responds to requests for information; develops, reviews, and distributes publications; and develops communications strategies to encourage individuals to achieve and maintain a healthy weight.
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NIH Publication No. 97-4191
e-text last updated: 16 March 1998