Prescription medications for the treatment of obesity

White Paper by: National Institutes of Health, Jan 15, 1996

Side Effects

Because appetite suppressant medications are used to treat a condition that affects millions of people, many of whom are basically healthy, their potential for side effects is of great concern. Most side effects of these medications are mild and usually improve with continued treatment. Although rare, serious and even fatal outcomes have been reported. Minor side effects of medications that affect serotonin levels (such as fenfluramine and dexfenfluramine) include dry mouth, sleep disturbance, sleepiness, frequent urination, and diarrhea. Medications that affect catecholamine levels (such as phentermine, diethylpropion, and mazindol) may cause symptoms of sleeplessness, nervousness, and euphoria (feeling of well-being).

Primary pulmonary hypertension (PPH) is a rare but potentially fatal disorder that affects the blood vessels in the lungs and results in death within 4 years in 45 percent of its victims. Patients who use appetite suppressant medications for more than 3 months have a greater risk for developing this condition, estimated at 1 in 22,000 to 1 in 44,000 patients per year. While the risk of developing PPH is very small, physicians and patients should be aware of this possible complication when considering the risks and benefits of using appetite suppressant medications in the long-term treatment of obesity. Patients taking appetite suppressant medications should contact their doctors if they experience any symptoms such as shortness of breath, chest pain, faintness, or swelling in lower legs and ankles.

Some animal studies have suggested that appetite suppressant medications can lead to damage to the central nervous system. Damage to the central nervous system has not been reported in humans. However, more studies on the effects of long-term appetite suppressant medication treatment on the central nervous system are needed. 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.

Commonly Asked Questions About Appetite Suppressant Medication Treatment

Q: Can medications replace physical activity or changes in eating habits as a way to lose weight?

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.

Q: Will I regain some weight after I stop taking appetite suppressant medications?

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.

Q: How long will I need to take appetite suppressant 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 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.