Alli, also known as orlistat, is a popular weight loss aid. Although Alli is safe for many people to use, it can cause problems for those taking certain medications, including the blood thinner Coumadin. If you take Coumadin, talk to your doctor before taking Alli or any other weight loss medication.
How Alli Works
To understand how Alli affects Coumadin, you need to understand the mechanism of Alli. Alli blocks the activity of an enzyme known as lipase. Lipase works in the intestines to break down fats, which allows absorption. By interfering with lipase, Alli impairs the intestinal absorption of fat from your diet. Because fats are calorie-dense, taking Alli keeps you from absorbing all the calories you obtain from your diet, making it easier to lose weight.
Alli and Vitamins
Alli does not interfere with the absorption of Coumadin, but it does block the absorption of some vitamins. Some vitamins, such as vitamins A, D, E and K are fat-soluble. This means that they dissolve better and are better absorbed when they are consumed in the presence of fat. By decreasing the amount of fat that your intestines absorb, Alli also interferes with the absorption of these fat-soluble vitamins.
Vitamin K and Coumadin
The problem with taking Alli and Coumadin stems from problems with vitamin K. Vitamin K is important for the formation of blood clots. Coumadin works by interfering with the activity of vitamin K in the blood and helps thin the blood. However, if your vitamin K levels drop due to using Alli, your blood can become too thin. This can cause you to bleed or bruise excessively and increases your risk of internal bleeding.
Considerations
Tell your doctor if you are taking Alli or are thinking of starting this medication, especially if you are also taking blood thinners. Your doctor may recommend against using Alli and if you do take it, he may need to monitor how it affects your blood clotting to prevent excessive bleeding. Your doctor may recommend alternative weight loss medications.
