Xenical Side Effects

In studies, commonly reported Xenical side effects included stomach pain, oily spotting, gas, and fecal urgency. These side effects are typically minor and easily treated -- especially if you pay attention to the amount of fat in your diet. Some side effects of Xenical, however, should be reported to your healthcare provider right away, such as kidney stones or signs of an allergic reaction.

 

An Introduction to Xenical Side Effects

As with any medicine, side effects are possible with Xenical® (orlistat); however, not everyone who takes the drug will experience side effects. In fact, most people tolerate it quite well. If Xenical side effects do occur, in most cases, they are minor and either require no treatment or are easily treated by you or your healthcare provider. 
 
(This article covers many, but not all, of the possible side effects with Xenical. Your healthcare provider can discuss a more complete list of Xenical side effects with you.)
 

Common Side Effects of Xenical

Xenical has been studied thoroughly in clinical trials. In these studies, the side effects that occur in a group of people taking the drug are documented and are then compared to side effects that occur in another group of people not taking the medicine. This way, it is possible to see what side effects occur, how often they appear, and how they compare to the group not taking the medicine.
 
In these studies, side effects that affected the digestive system were common (as would be expected, based on how Xenical works). These Xenical side effects included:
 
  • Oily spotting (uncontrolled anal oil seepage) -- in up to 26.6 percent of people
  • Abdominal pain (stomach pain) or discomfort -- up to 25.5 percent
  • Gas with a small amount of oil or stool -- up to 23.9 percent
  • Fecal urgency (an urgent but controlled need to have a bowel movement) -- up to 22.1 percent
  • Fatty or oily stool -- up to 20 percent
  • Oily evacuation (bowel movements of just oil, without stool) -- up to 11.9 percent
  • Increased frequency of bowel movements -- up to 10.8 percent
  • Nausea -- up to 8.1 percent
  • Uncontrolled, spontaneous bowel movements (known as fecal incontinence) -- up to 7.7 percent.
     
Many of the side effects that affect the digestive tract can be avoided or reduced by decreasing the amount of fat in your diet. Because Xenical decreases the absorption of fat, more fat stays in the digestive tract, causing many of the bothersome and sometimes embarrassing Xenical side effects. You are more likely to experience these side effects if you eat too much fat. As you continue to take Xenical, you will learn how different foods and different amounts of fat affect you. In fact, in studies, these side effects occurred much less commonly in the second year of treatment. If you have consumed a meal that is high in fat and have taken Xenical, you may want to prepare for possible side effects.
 
Other common side effects (occurring in 4 to 40 percent of people) included:
 
 
(Xenical Side Effects Continued: Page 2)
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Written by/reviewed by: Kristi Monson, PharmD; Arthur Schoenstadt, MD
Last reviewed by: Kristi Monson, PharmD;