Facts & Myths About Xenical

Myth: Xenical will give me side effects.

Fact: Not everyone who takes Xenical will get side effects. Some side effects, especially those that affect the digestive tract are common, especially at the beginning of taking Xenical. In clinical trials, greater than 1 out of 10 people had side effects affecting the digestive tract. Eating a low fat, low calorie diet helps to avoid digestive side effects. When taking Xenical other types of side effects are possible, but the side effects range in frequency from common, uncommon or rare among the individuals taking this medication.

Myth: Xenical and Alli are the same.

Fact: Xenical and Alli are different. Xenical is a stronger medication than Alli. Both Xenical and Alli are used for weight reduction and for maintaining the lower weight. Both Xenical and Alli contain the same active ingredient, orlistat. Both Xenical and Alli are taken with every one of the three main meals (breakfast, lunch, and dinner) daily that include fat. The amount of orlistat in each Xenical capsule (120 mg) is twice as much as the amount of orlistat (60 mg) in each Alli pill. So, the daily dose of Xenical contains 360mg of orlistat in total, whereas the daily dose of Alli contains 180mg of orlistat. Due to the fact that the daily dose of orlistat in Xenical is twice as much as the daily dose of orlistat in Alli, Xenical is more effective in reducing weight than Alli. Another difference is that Xenical can be obtained only by prescription. Alli on the other hand can be purchased over-the-counter.

Myth: Xenical is addictive.

Xenical is not addictive. So, there is no potential for overuse of Xenical by the person for whom it has been prescribed.

Myth: I don’t need a prescription for Xenical.

Fact: Xenical requires a prescription. In order to get a prescription for Xenical, the person has to be an adolescent or an adult. Secondly, they must be overweight to a certain extent, which has not been helped adequately by diet and exercise. This might be connected to a weight-related condition, or certain other medical difficulties.

Myth: I can’t take antibiotics with Xenical.

Fact: You can take antibiotics (medicines that fight bacterial infections) with Xenical. Antibiotics do not interfere with the action of Xenical, and vice versa; Xenical does not interfere with the actions of antibiotics. But Xenical interferes with certain medications (classified as antivirals) used to treat HIV and AIDS. In addition, if you take certain other medications for other medical conditions with Xenical, the doses of the other medications may have to be adjusted, or you may have to be monitored medically for side effects.

Myth: I can’t take oral contraceptives with Xenical.

Fact: You can take oral contraceptives with Xenical, however, if you have severe diarrhoea (six to eight bowel movements that are watery within a 24-hour period of time), this can lower the effectiveness of hormonal contraception. Take an extra pill from the end of the package of oral contraceptives for the following month and use an additional method of contraception (e.g., condoms) while you are experiencing diarrhoea and for two days following your recovery. In the case of severe diarrhoea while taking Xenical and an oral contraceptive, consult your doctor, a family planning clinic or your pharmacist to see if emergency contraception (the morning after pill) is recommended. You should use an additional method of contraception (such as condoms) until you recover.

Myth: Xenical can be used by anyone.

Fact: Only some people can get a prescription for Xenical, if they are an adolescent or an adult, are overweight to a certain extent, have not been helped sufficiently by diet and exercise, have a weight-related condition and do not have certain medical conditions. Xenical is prescribed for weight reduction only if the patient is at least 12 years of age and has one of the following conditions:

  • A body mass index (ratio of weight to height) of at least 30
  • A BMI of 27.9 AND a weight-related condition such as high blood pressure, heart problems, high level of fat in the blood and diabetes.

In order for Xenical to be effective and to avoid certain side effects you have to be on a low fat, low calorie diet and perform exercise regularly.

Xenical cannot be taken by individuals who have any of the following conditions:

  • Allergic reaction to orlistat or any of the inactive ingredients in Xenical
  • Pregnancy or suspected pregnancy
  • Breastfeeding an infant
  • Problems with gallbladder, as loss of significant weight can increase risk of gallstones
  • Chronic malabsorption syndrome, which means that your body cannot absorb foods in the correct way

If you have any of the following conditions, ask your doctor whether Xenical is right for you:

  • Non-insulin dependent diabetes mellitus (NIDDM, also called type 2 diabetes)
  • Type 1 (insulin dependent) diabetes
  • High levels of cholesterol in the blood
  • Inflammation of the pancreas (called pancreatitis)
  • High blood pressure
  • Metabolic syndrome, which is a combination of type 2 diabetes, high levels of cholesterol, and high blood pressure
  • Thyroid that is underactive
  • Kidney stones
  • Problems with the liver
  • Anorexia (thinking that you are overweight when you are not and avoiding food because of that perception)
  • Bulimia (vomiting in order to lose weight)


Myth: Xenical is the only clinically proven diet pill.

Fact: Orlistat is the only clinically proven inhibitor of lipase enzymes, which block absorption of dietary fat in the body and lead to weight reduction when used with a low fat, low calorie diet and regular exercise. Orlistat is the active ingredient in the prescription medication; Xenical and the over-the-counter medication; Alli. Xenical has twice the amount of orlistat that Alli does, so Xenical is more effective in reducing weight. At the present time Xenical is the only clinically proven prescription diet pill that is covered by the NHS in the UK. Other clinically proven diet pills include certain appetite suppressants. However, appetite suppressants, such as phentermine, are not covered by the NHS and have to be obtained by prescription from private weight loss (bariatric) physicians who practice in slimming clinics.


  1. Accessed at http://www.emedexpert.com/facts/orlistat-facts.shtml