Why does taking Orlistat cause black oily stools?
I recently noticed black, oily stools resembling fatty substances after taking Orlistat, and I've also experienced more frequent bowel movements. Could you please explain why this is happening? Is this a normal reaction to the medication?
Doctor's answer (1)
Passing black oily stools is usually a normal response to taking orlistat, but it may also be caused by side effects of the medication or upper gastrointestinal bleeding.
Orlistat is a medication commonly used in the treatment of obesity. Its mechanism of action involves inhibiting the activity of gastrointestinal lipases, thereby preventing the digestion and absorption of some dietary fats. Unabsorbed fats are excreted in the feces.
The phenomenon of "passing black oil," which may occur after taking orlistat, is actually the result of unabsorbed fats combining with bile acids, altering the color and texture of the stool. The stool may appear oily and black or dark green, a condition medically termed steatorrhea.
Common side effects of orlistat include gastrointestinal discomfort, such as diarrhea and abdominal pain. These side effects may lead to changes in stool color and consistency, resulting in the passage of black oily stools. If the stool passed is black and tarry, upper gastrointestinal bleeding should be considered.
It is important to note that long-term and excessive use of orlistat may lead to deficiencies in fat-soluble vitamins. When using orlistat, it is essential to follow medical instructions to ensure safe medication use.
