Common Side Effects

• In pre-approval clinical trials with Alli, as detailed by eMedTV, the most common side effects were abdominal pain, an urgent need to have a bowel movement, gas, oily anal seepage, and fatty or oily stool. These effects were experienced by 17 to 20 percent of people in some studies.
  
  

Other Side Effects

• Other common side effects occurring in 3 to 12 percent of people were diarrhea, bowel movements of just oil, soft stools, greater frequency of bowel movements and uncontrolled bowel movements (incontinence).
  
  

Non-Gastrointestinal Side Effects

• Back pain was another common side effect. Additionally, up to 10.6 percent of participants in some studies developed sinus infections.
  
  

Serious Side Effects

• Alli is associated with development or worsening of kidney stones and gallbladder disease. It also can cause severe stomach pain.
  
  

Allergic Reaction

• Rarely, some people have an allergic reaction to Alli. Signs are rash or hives, itching, swelling of the face or mouth, wheezing, difficulty breathing, difficulty swallowing and persistent stomach pain.