Xenical: An Anti-Obesity Drug

Xenical is a drug that works by absorbing fat instead of suppressing appetite. This means that approximately 30% of the fats ingested in foods are eliminated without metabolizing.
Xenical: An Anti-Obesity Drug

Last update: 23 August, 2020

Xenical is an anti-obesity drug whose active substance is orlistat. This active principle exerts its effect by reducing the absorption of the fats you consume in meals by 30%.

How does Xenical work?

Xenical is a drug that works by absorbing fats from foods. However, it doesn’t affect appetite, like other types of drugs indicated to treat obesity do.

Your body dissolves the fats that you consume with your meals by the action of enzymes called lipases. This drug exerts its action on them, preventing the absorption of fats. As a consequence of this action, 30% of the fats you ingest in your meals are eliminated without metabolizing in the feces.

Due to its mechanism of action, Xenical helps people lose weight and keep the weight off for a long time. It can also improve some cardiovascular risk factors, such as high blood pressure, high cholesterol levels, and high glucose levels.

Indications of Xenical

An obese man.

This drug is indicated for obese people with a body mass index (BMI) equal to or greater than 30 kg/m2. However, it’s also an option in the case of overweight patients with a BMI equal to or greater than 28 kg/m2 provided that, in addition to being overweight, they have associated risk factors.

If the patient doesn’t lose at least 5% of their initial weight after three months of treatment with Xenical, they need to stop the treatment.

How to take Xenical

The usual dose in adults is 120 mg. They have to take it immediately before, during, or up to an hour after each main meal.

According to studies, the main route of elimination is fecal excretion. Almost 100% of the dose is eliminated in the feces, unaltered. The effect of this drug causes a big increase in fecal fat after 24-48 hours.

When you start treatment with this drug, you should also follow a balanced low-calorie diet. Your diet must contain a daily intake of fats, carbohydrates, and proteins, distributed among the three main meals of the day.

Contraindications of this drug

Like all medications, Xenical has some contraindications, including the following:

  • Malabsorption syndrome
  • Children
  • Lactating women

There are no studies of the effect of this drug in obese patients who also have liver and/or kidney disorders, as well as in the elderly and children.

An obese man weighing himself.

Does it interfere with other medications?

Xenical interacts with other drugs, due to the fact that it modifies the absorption of certain active ingredients, which can change its effects.

Very rarely, hypothyroidism with thyroid abnormalities can occur. This effect can occur as a consequence of this drug decreasing the absorption of iodine salts or levothyroxine.

Additionally, Xenical decreases the absorption of antiepileptic drugs, which can lead to seizures. Also, it reduces the absorption of fat-soluble vitamins, such as vitamin E and beta-carotene. For this reason, while you’re taking this drug, the medical professional may advise you to take a vitamin supplement. However, it’s important to follow a balanced diet rich in fruits and vegetables.

On the other hand, Xenical enhances the effect of some medications that are used to lower blood cholesterol levels. Therefore, it may be necessary for patients to readjust the dose of the cholesterol treatment they’re taking.

If you’re taking birth control pills, to prevent possible accidents, which could occur if you suffer from severe diarrhea due to the effect of Xenical, the medical professional will recommend you to use barrier contraceptive methods.


Xenical helps you lose weight and keep it off. In addition, it helps you to improve cholesterol levels and reduce other cardiovascular risk factors.

Nevertheless, it’s essential to follow a low-calorie diet during treatment and exercise regularly. If you have any questions, ask your doctor or pharmacist.

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  • Torgerson, J. S., Hauptman, J., Boldrin, M. N., & Sjöström, L. (2004). XENical in the Prevention of Diabetes in Obese Subjects (XENDOS) Study: A randomized study of orlistat as an adjunct to lifestyle changes for the prevention of type 2 diabetes in obese patients. Diabetes Care. https://doi.org/10.2337/diacare.27.1.155

  • Drew, B. S., Dixon, A. F., & Dixon, J. B. (2007). Obesity management: Update on orlistat. Vascular Health and Risk Management.

  • Romero Ramos, H., Martínez Brocca, M. A., Pereira Cunill, J. L., & García Luna, P. P. (2005). Tratamiento farmacológico de la obesidad. Revista Espanola de Obesidad. https://doi.org/10.11565/arsmed.v26i1.1210