What Is Orlistat?

Orlistat is a drug that is used to promote weight loss in persons who are overweight or obese. The medication is available both as a prescription and over the counter under various brand names. Orlistat belongs to a class of medications known as lipase inhibitors, which prevent dietary fat from being absorbed in the digestive tract. A low-calorie, low-fat diet and exercise program should be followed for ultimate weight loss success.

In clinical studies, orlistat has been shown to have several benefits for patients who are obese. Patients have been shown to lose significantly more weight by dieting and taking orlistat than by dieting alone. This drug also has been shown to effectively block the absorption of more than 20 percent of consumed fat in some patients.

Physicians typically prescribe or recommend this medication for patients who are obese with a body mass index of 30 or greater. Patients who have a body mass index of 27-30 might also be considered for medical weight loss intervention if co-morbid conditions such as high blood pressure, diabetes or hypercholesterolemia are present. Although orlistat is available as an over-the-counter medication, patients should be monitored by a physician to ensure against drug-drug interactions and nutrient deficiencies. The most common side effects of orlistat include loose bowel movements and the urgent need to have a bowel movement.

Some vitamins, including vitamins A, D, E and K, bind to fat, so orlistat might inhibit their absorption. Patients taking this medication should therefore take a daily multivitamin that contains these fat-soluble vitamins. They also should separate their intake of the medication and the supplement by at least two hours to prevent interaction. Vitamin K is involved in blood clotting, so patients who are taking warfarin should have their blood levels monitored regularly while taking orlistat to prevent abnormal bleeding.