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 was 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these reports, the manufacturer has voluntarily withdrawn two medications,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 studies lasting more than 2 years evaluating the safety or effectiveness
of weight-loss medications. In particular, the safety and effectiveness
of combining more than one weight-loss medication or combining weight-loss
medications with other medications for the purpose of weight loss is unknown.
Weight-loss 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.
Most available weight-loss medications are "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.
In 1999, the drug orlistat was approved by the Food and Drug Administration
(FDA) as an obesity treatment. Orlistat works by reducing the body's ability
to absorb dietary fat by about one third.
Most currently available weight-loss medications are approved by the
U.S. Food and Drug Administration (FDA) for short-term use, meaning a
few weeks or months. Sibutramine and orlistat are the only weight-loss
medications approved for longer-term use in significantly obese patients,
although the safety and effectiveness have not been established for use
beyond 1 year. (See table 1 for the generic and trade names of prescription
weight-loss 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 weight-loss medication at a time (combined drug treatment) is
an example of an off-label use. Using weight-loss medications other than
sibutramine or orlistat for more than a short period of time (i.e., more
than "a few weeks") is also considered off-label use.
Table 1
Prescription Weight-Loss Medications
| Generic Name |
Trade Name(s) |
| Dexfenfluramine |
Redux (withdrawn) |
| Diethylpropion |
Tenuate, Tenuate dospan |
| Fenfluramine |
Pondimin (withdrawn) |
| Mazindol |
Sanorex, Mazanor |
| Orlistat |
Xenical |
| Phendimetrazine |
Bontril, Plegine, Prelu-2, X-Trozine |
| Phentermine |
Adipex-P, Fastin, Ionamin, Oby-trim |
| Sibutramine |
Meridia |
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Several weight-loss 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 weight-loss
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 year. Both orlistat and
sibutramine have been studied for as long as 2 years in some patients.
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.
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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, Xenical/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.
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Over the short term, weight loss in obese individuals may reduce a number
of health risks. Studies looking at the effects of weight-loss medication
treatment on obesity-related health risks have found that some agents
lower blood pressure, blood cholesterol, and 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 weight-loss medications can improve health.
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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 many weight-loss medications. 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 4 to 6 months while still on medication. While
some patients and physicians may be concerned that this shows tolerance
to the medications, the 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.
- 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. The
belief that persons choose to be obese adds to the hesitation of health
professionals and patients to accept the use of long-term appetite-suppressant
medication treatment to manage obesity. Obesity, however, is more appropriately
considered a chronic disease than a lifestyle choice. Other chronic
diseases, such as diabetes and high blood pressure, are managed by long-term
drug treatment, even though these diseases also improve with changes
in lifestyle, such as diet and exercise. Although this issue may concern
physicians and patients, social views on obesity should not prevent
patients from seeking medical treatment to prevent health risks that
can cause serious illness and death. Appetite-suppressant medications
are not "magic bullets" or a one-shot fix. They cannot take the place
of improving one's diet and becoming more physically active. The major
role of medications appears to be to help a person stay on a diet and
exercise plan to lose weight and keep it off.
- Side Effects
Because weight-loss 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. Rarely, serious
and even fatal outcomes have been reported. Two approved appetite-suppressant
medications that affect serotonin release and reuptake have been withdrawn
from the market (fenfluramine, dexfenfluramine). Medications that affect
catecholamine levels (such as phentermine, diethylpropion, and mazindol)
may cause symptoms of sleeplessness, nervousness, and euphoria (feeling
of well-being).
Sibutramine acts on both the serotonin and catecholamine systems,
but unlike fenfluramine and dexfenfluramine, sibutramine does not
cause release of serotonin from cells. The primary known side effects
of concern with sibutramine are elevations in blood pressure and pulse,
which are usually small but may be significant in some patients. People
with poorly controlled high blood pressure, heart disease, irregular
heart beat, or history of stroke should not take sibutramine, and
all patients taking the medication should have their blood pressure
monitored on a regular basis.
Some side effects with orlistat include oily spotting, gas with discharge,
urgent need to go to the bathroom, oily or fatty stools, an oily discharge,
increased number of bowel movements, and inability to control bowel
movements. 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.
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. It should be noted
that the vast majority of cases of PPH have occurred in patients who
were taking fenfluramine or dexfenfluramine, either alone or in combination.
There have been only a few case reports of PPH in patients taking
phentermine alone, although the possibility that phentermine alone
may be associated with PPH cannot be ruled out. No cases of PPH have
been reported with sibutramine, but because of the low incidence of
this disease in the underlying population, it is not known whether
or not sibutramine may cause this disease.
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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. The use of weight-loss 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 weight-loss medications?
A: Probably. Most studies show that the majority of patients who stop
taking weight-loss 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 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 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 weight-loss medications are for many years of use.
Q: What dosage of weight-loss medication would be right for me?
A: There is no one correct dose for weight loss medications. Your doctor
will decide what works best for you based on his or her evaluation of
your medical condition and response to treatment.
Q: I only need to lose 10 pounds. Are weight-loss medications appropriate
for me?
A: Weight-loss 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.
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Before choosing weight-loss medication 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.
How will I be evaluated to determine if I am an appropriate candidate
for weight-loss medication?
Your physician will look at a number of factors to determine if you
are a good candidate for prescription weight-loss medication. 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:
- Take a careful medical history and perform a physical examination.
- Look at your personal weight history.
- Ask whether you have relatives with illnesses related to overweight,
such as
type 2 diabetes mellitus
or heart disease.
- Discuss the methods you have used to lose weight in the past.
- Evaluate your risk for obesity-related health problems by measuring
your blood pressure and doing blood tests.
If your doctor determines that you have obesity-related health problems
or are at high risk for such problems, and if you have been unable to lose
weight or maintain weight loss with nondrug treatment, he or she may recommend
that you use prescription weight-loss medications. Weight-loss medications
may be appropriate for carefully selected patients who are at significant
medical risk because of their obesity. They are not recommended for 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.
What other medical conditions or medications might influence my
decision to take a weight-loss medication?
It is important that you notify your physician if you have any of the
following medical conditions:
- Pregnancy or breast-feeding
- History of drug or alcohol abuse
- History of an eating disorder
- 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
- Planning to have surgery that requires general anesthesia
What type of program will be provided along with the medication to
help me improve my eating and physical activity habits?
Studies show that weight-loss 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.
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If you and your doctor believe that the use
of weight-loss medications may help you, discussing the goals of treatment
is important. 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 weight-loss
medications for cosmetic purposes is not appropriate.
Weight-loss 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 affects 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 weight-loss 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 2 years. 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.
End note: This e-text is a modified version of a review article
on the long-term use of appetite-suppressant medications to manage obesity
appearing in a 1996 issue of the Journal of the American Medical Association.
A table
summarizes the studies included in the review article. Both the review
article and this fact sheet were developed with the advice of the National
Task Force on Prevention and Treatment of Obesity, a working group of
leading obesity and nutrition researchers from across the country. This
e-text was revised in October 1997 in response to additional information
reported regarding an association between valvular heart disease and certain
weight-loss medications, in February 1998 in response to the approval
of sibutramine, and in November 2000 in response to the approval of orlistat.
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Weight-control Information Network
1 Win Way
Bethesda, MD 20892-3665
Phone: (202) 828-1025 or 1-877-946-4627
Fax: (202) 828-1028
Email: win@info.niddk.nih.gov
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.
Publications produced by the clearinghouse are carefully reviewed by
both NIDDK scientists and outside experts.
This e-text is not copyrighted. The network encourages users of this
e-pub to duplicate and distribute as many copies as desired.
From the NIDDK
NIH Publication No. 97-4191
December 1996
Updated June 2003
http://www.niddk.nih.gov/health/nutrit/pubs/presmeds.htm
Also see:
do you know the health risks of being overweight?
understanding adult obesity
