Explore the possible side effects of orlistat and how they can be avoided.

What is Orlistat?

Orlistat is the active ingredient in Xenical and Prolistat. It is used to treat people with a BMI greater than 30. It can be considered for those with a BMI of greater than 27 with other risk factors such as diabetes, high blood pressure, high cholesterol or other heart conditions. 

Orlistat belongs to a group of medicines called lipase inhibitors. It works by targeting the absorption of dietary fats in the body rather than suppressing appetite. Orlistat is to be used with a low calorie diet, low fat diet, and exercise program to achieve weight loss.  

Xenical capsules are 120mg in strength and are to be taken one with each meal (3 times a day). It’s advisable to use XENICAL alongside a balanced calorie-controlled diet that includes an average of 30% of calories from fat, along with a variety of fruits and vegetables. 

If a dose is missed, it can be taken up to 1 hour after the meal. If it’s been a few hours, individuals should skip the missed dose and continue treatment with the next meal. It is not to be used in pregnant and breast-feeding women or people under 18 years of age. 

Information on Orlistat

Side effects of Orlistat

Bowel discomfort:

Xenical works by blocking the absorption of dietary fats which can lead to some digestive side effects. Individuals can experience urgency to have a bowel movement or increased number of bowel movements with/without oily or loose stools. 

They may notice oily spots on their underwear. Some people can also experience flatulence with an oily discharge from rectum. 

Abdominal discomfort:

Some individuals may experience abdominal pain/stomach pain or cramping. It is also reported that people may get indigestion, nausea or bloating whilst taking Xenical three times daily. 

Bowel or abdominal discomfort are more likely to occur when individuals consume a high-fat meal hence it’s important to follow a low-fat diet or to spread or divide the fat content between the three meals to limit digestive issues. 

The common reported side effects of orlistat are usually mild to moderate and usually resolve when medication is discontinued.

Xenical may have some interactions with other medications. A common drug interaction is with the contraceptive pill. Whilst taking xenical, women may experience severe diarrhea which may hinder the absorption of the pill in the body. It is thus recommended to use additional protection to prevent unwanted pregnancy. 

Other interactions can be with heart medications, blood thinners or diabetes medications. There is a possibility that these conditions are due to excess weight so once weight reduces, call your doctor for a review of condition and medication status.  

Following a diet to lose weight may risk deficiencies in certain vitamins and minerals and especially if using Xenical as an addition. Orlistat works by preventing absorption of fat and can also affect absorption of fat soluble vitamins and minerals. 

It is important to ensure maintenance of normal levels of nutrients and why it’s recommended to take a daily multivitamin as a supplement. It should be consumed 2 hours after the xenical tablet or at bedtime.

The serious side effects include experiencing symptoms of liver disease such as loss of appetite, dark urine or light colored stools, yellowing of skin or eyes etc. Individuals can also have symptoms of pancreatitis which cause severe stomach pain, nausea and vomiting. These are rare serious side effects and may need urgent medical attention.

Consulting doctor or pharmacist

It is best to consult with a health professional for any bothering side effects, allergic reactions or serious adverse effects.

To begin or continue the weight loss journey, having a team of doctors and dietitians can be extremely important for a successful outcome.

Consult a dietitian


XENICAL orlistat 120mg | Therapeutic Goods Administration (TGA)