Xenical (orlistat) is a prescription lipase inhibitor intended for the treatment of obesity in patients carrying a lot of excessive weight. The effects of Xenical are based on preventing the intestines from absorbing too much fat from the food you consume. Make sure you talk to your health care provider before taking Xenical and report any drugs you are taking at the moment that can affect the success of your treatment because of causing interactions with Xenical. The following ones are important to mention: medications for diabetes, anticoagulants, medications to control blood pressure, medications for thyroid, and other weight loss medications. However, if you are taking any other herbal supplements or vitamins, or drugs not mentioned ere – also tell your doctor about them. If you have eating disorder, pancreatitis, gallbladder disease, thyroid disease, diabetes, or kidney stones, your dose may need to be adjusted- so report those medical issues to your doctor as well. Mild side effect are common and include gas with oily spotting, loose stools, headache, irregular menstrual periods, oily or fatty stools, stomach pain, anxiety, urgent need to have a bowel movement, oily spotting, and increased number of bowel movements.