Alli is a nonprescription drug for weight loss that contains orlistat, the same active pharmaceutical ingredient found in the prescription drug Xenical that has been tested in more that 30,000 patients. Alli works by inhibiting 25 percent of dietary fat from getting absorbed into the body. Alli is an effective weight loss product when used with a low calorie, low fat diet, exercise and a multivitamin. However, there are some unpleasant and potentially dangerous side effects.
Gastrointestinal Effects
Alli has a unique mechanism of action for a weight loss drug. Alli blocks lipase, an enzyme that normally breaks down dietary fat and enables small fat molecules called fatty acids to get absorbed into the body. By blocking lipase, about 25 percent of the fat in foods do not get broken down or absorbed into the body. The result is fewer calories from food enter the body. The unabsorbed fat instead travels through the intestinal tract and out of the body through the anus.
People who take Alli may notice some changes in bowel movements, especially during the first few weeks of using the drug. Some of the common gastrointestinal side effects from Alli include intestinal gas, a sudden and urgent need to defecate, loose, oily stools, diarrhea and more frequent and hard to control bowel movements, according to MayoClinic.com. These side effects could occur when least expected. The manufacturer states that these side effects are more likely to occur after meals that contain more than 15g of fat. Furthermore, foods cooked in oil are likely to exacerbate these side effects. Therefore, it is best to choose meals low in fat.
Vitamin Deficiencies
Alli can also reduce the amount of fat soluble vitamins that get absorbed into the body from food and supplements. These include beta carotene and vitamins A, D and E. Vitamin deficiencies could lead to a cascade of biological effects that could increase risk for various medical conditions. People who take Alli for weight loss need to take a daily vitamin supplement that contains these fat soluble vitamins at a time different from when Alli is taken to prevent potential nutrient deficiencies, according to MayoClinic.com. The National Institute of Diabetes and Digestive and Kidney Diseases recommends that people being treated with orlistat medications take a multivitamin at least two hours before or after taking the drug.
Other Side Effects
The Food and Drug Administration announced in 2009 that it received 32 reports of serious liver injury in patients taking orlistat, of which 27 were hospitalized and six resulted in liver failure. Symptoms from these adverse effects include stomach pain and jaundice, a yellowing of the skin or whites of the eyes. MayoClinic.com recommends that people who take Alli that experience fatigue, fever, jaundice or brown urine should contact a physician. Other side effects from Alli include influenza, upper and lower respiratory infections, back pain, headaches, dizziness, rash and dry skin, inflammation of the vagina, urinary tract infections, anxiety, depression and high blood pressure, according to Drugs.com.
References
- GlaxoSmithKline: Alli
- Genentech: Xenical Prescribing Information
- MayoClinic.com: Alli Weight-Loss Pill: Does It Work?
- National Institute of Diabetes and Digestive and Kidney Diseases: Prescription Medications for the Treatment of Obesity
- Food and Drug Administration: FDA Issues Early Communication About Ongoing Safety Review of Weight Loss Drug Orlistat. Review Includes Both Prescription Drug Xenical and OTC Drug Alli.
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