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Medication in the Treatment of Obesity (cont.)

What Medications Are Used in the Treatment of Obesity?

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These medications have been approved by the U.S. Food and Drug Administration (FDA) for the treatment of obesity. They are available in the United States only by prescription. Ask your health care professional about these medications.

Sibutramine (Meridia) is a prescription medication approved by the FDA in 1996. It may be recommended for people who are more than 30 pounds overweight. Unlike phentermine, sibutramine is a nonamphetamine appetite suppressant that may also have antidepressant properties.

  • This drug may increase blood pressure, so regular monitoring is essential.
  • It affects levels of two brain chemicals, serotonin and norepinephrine, which control mood and appetite.
  • In clinical trials, the average weight loss was 5%-10% of body weight, when combined with a reduced calorie diet. It may also help to maintain weight loss.
  • Sibutramine may cause serotonin syndrome, a rare but serious condition.
  • This medication should not be used in the following instances:
    • People younger than 16 years
    • Pregnant or breastfeeding women
    • People taking an MAO inhibitor medication or an SSRI for depression (such as Prozac, Zoloft, or Paxil)
    • Anyone taking other prescription or over-the-counter diet aids
    • People taking prescription pain relievers such as Demerol, Duragesic, or Talwin

Orlistat (Xenical, Alli) is a prescription medication approved by the FDA in 1999. Your doctor may prescribe it if you weigh more than 30% over healthy body weight or have a BMI greater than 30.

  • Orlistat works in the digestive system to block the digestion of about 30% of dietary fat that you eat. The undigested fat is then eliminated in bowel movements.
  • You must adhere to a reduced-calorie diet that contains no more than 30% fat. This medication will also block digestion of the fat-soluble vitamins A, D, E, and K, so a supplement should be taken.
  • The undigested fat will cause changes in your bowel movements. They will increase in frequency and number. You may be unable to control your bowel movements. They may also be oily in consistency. These effects will be more pronounced if your meals contain more than 30% fat.
  • Over one year, people treated with orlistat in addition to a reduced fat and calorie diet lost an average of 13.4 pounds. A comparison group that used diet only without orlistat lost an average of 5.8 pounds.
  • This medication should not be used in the following instances:
    • People with chronic problems absorbing food
    • Anyone with gallbladder problems
    • Pregnant or breastfeeding women
  • Lorcaserin (Belviq 10 mg one to two times daily) was just approved by the FDA in June 2012. It may be considered if your BMI is 30 or greater or if you have a BMI greater than 27 with weight-related conditions. Studies demonstrated that almost half of patients lost an average of 5% of their body weight when combined with diet and exercise (compared to 25% of patients with diet and exercise alone). Lorcaserin works by activating the serotonin 2C receptor in the brain, which helps you feel full after smaller portions. The most common side effects were headache, nausea, and dizziness.
  • Qsymia (combination of phentermine and topiramate) was just approved by the FDA in July 2012. It is only approved for those with a BMI greater than 27 with weight-related conditions. When combined with diet and exercise, studies have shown that half of the participants lost 10% of their body weight and four-fifths lost 5% (which equates to 12 pounds in a 227-pound person). Topiramate is associated with a high risk of birth defects such as cleft lip and palate. Phenteramine (an appetite suppressant) was one of the ingredients in fen-phen and is associated with an elevation in heart rate. Because of these potentially serious side effects, Qsymia is only available through mail order. Other side effects include tingling, dizziness, alterations in taste, insomnia, dry mouth, and constipation.


Phentermine (Adipex-P, Ionamin, Fastin) is a prescription stimulant medication approved by the FDA in 1959. It is an appetite suppressant. It is approved for short-term use (a few weeks) for weight loss in addition to calorie restriction, exercise, and behavioral modification.

  • It is the phen in the fen-phen combination that was taken off the market in 1997 because of serious safety concerns. It is currently found in the recently approved medication, Qsymia as discussed above.
  • The serious heart and lung conditions caused by the combination of phentermine and fenfluramine or dexfenfluramine cannot be completely ruled out with use of phentermine alone. Although phentermine remains on the U.S. market, it has been taken off the market in Europe because of safety concerns.
  • Phentermine works by increasing the amount of the catecholamine norepinephrine in the brain. This stimulates the nervous system, suppressing appetite and possibly increasing the number of calories burned.
  • Many people taking this drug complain of palpitations (rapid heart beat), nervousness, restlessness, insomnia, shakiness, or feeling anxious.
  • This drug may give a positive result for stimulants on a urine drug test.
  • This drug has the potential for abuse. Many health care professionals are reluctant to prescribe phentermine, especially now that safer drugs are available.
  • Phentermine should not be used in the following instances:
Medically Reviewed by a Doctor on 11/21/2017
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