The information provided here is meant to give you a general idea about each of the medications listed below. Only the most general side effects are included, so ask your health care provider if you need to take any special precautions. Use each of these medications as recommended by your health care provider, or according to the instructions provided. If you have further questions about usage or side effects, contact your health care provider.

Medications for obesity may be used to supplement a weight loss program that includes reduced caloric intake, regular exercise, other behavior changes, and psychological counseling, if appropriate. However, medications alone are not a viable option for losing weight and keeping it off.

Prescription Medications

Central nervous system medications

  • Phentermine
  • Sibutramine (Meridia)

Fat absorption blockers

  • Orlistat (Xenical)

Over-the-Counter (OTC) Medications

OTC medicines advertised as promoting weight loss are generally considered ineffective. They can, however, have potential side effects, such as headaches, anxiety, and heart palpitations.

Prescription Medications

Cental nervous system medications

Common names include:

  • Sibutramine (Meridia)
  • Phentermine
    • Profast (SA)
    • Fastin
    • Ionamin
    • Adipex-P

These medications act on your brain to suppress your appetite. Phentermine is classified as a stimulant. Of drugs in this class, only sibutramine and phentermine are recommended for obesity treatment, and only sibutramine is recommended for long-term use up to about 2 years. The starting dose of sibutramine is 10 mg per day. Phentermine doses start at 20 to 30 mg a day, often in divided doses one-half hour before meals. It is only recommended for short-term use (up to about 12 weeks). Used alone, phentermine does not seem to produce the heart damage caused by its combination with fenfluramine (Phen-Fen), which was withdrawn from the market. (Fenfluramine was also withdrawn from the market in 1997 because of side effects causing heart damage.)

Possible side effects include:

Phentermine

  • Abuse
  • Tolerance to the effect
  • Interactions with many psychoactive drugs
  • Elevation of blood pressure
  • Heart problems
  • Nervousness, insomnia, shakiness, headache, mental changes
  • Dry mouth, nausea, diarrhea, constipation
  • Difficulty urinating
  • Rashes

Sibutramine

  • Elevation of blood pressure
  • Increased heart rate
  • Dry mouth, constipation
  • Increased sweating
  • Headache
  • Insomnia

Fat Absorption Blockers

Common names include:

  • Orlistat (Xenical)

Taken at a dose of 120 milligrams three times a day, Orlistat prevents ingested fat from being absorbed by blocking digestive enzymes. About 30% of the fat you eat will remain in your bowels. In as many as 25% of people taking the drug, the fat is excreted by the body between bowel movements as an oily discharge. It is recommended for long-term use (up to about 2 years).

Possible side effects include:

  • Staining of underwear
  • Gas
  • Pressure to empty bowels
  • Leakage of stool
  • Increased frequency of bowel movements

Special Considerations

Whenever you are taking a prescription medication, take the following precautions:

  • Take them as directed—not more, not less, not at a different time.
  • Do not stop taking them without consulting your health care provider.
  • Don’t share them with anyone else.
  • Know what effects and side effects to expect, and report them to your health care provider.
  • If you are taking more than one drug, even if it is over-the-counter, be sure to check with a physician or pharmacist about drug interactions.
  • Plan ahead for refills so you don’t run out.