Is Orlistat Safe?

According to the World Health Organization Regional Office for Europe, obesity is one of the greatest public health challenges of the 21st century.
The prevalence of obesity has tripled in many countries of the WHO European Region since the 1980s.
The number of people affected by obesity is steadily increasing, especially among children.
Obesity increases the risk of developing several noncommunicable diseases such as cardiovascular disease, cancer and diabetes.
2-8% of health costs and 10-13% of deaths in different parts of Europe are due to obesity.
More than 42 million children under the age of 5 years were overweight in 2013.

Content of this article

What is obesity?

Obesity is a condition where a person has accumulated so much body fat that it might have a negative effect on their health.
If a person’s body weight is at least 20% higher than it should be, he or she is considered obese. If your Body Mass Index (BMI) is between 25 and 29.9 you are considered overweight. If your BMI is 30 or over, you are considered obese.


What is the body mass index (BMI)?

The body mass index (BMI) is a measure of a person’s weight relative to their height that links fairly well with body fat. The BMI is accepted as the most useful measure of obesity for adults (those aged 18 years and over) when only weight and height data are available. It is calculated as a person’s weight (in kilograms) divided by the square of his or her height (in meters).
BMI = weight (kg) / height (m²)
The following subdivision (according to the WHO) is used to classify results for the BMI:

  • < 18.50: underweight;
  • 18.50 – < 25.00: normal range;
  • ≥ 25.00: overweight;
  • ≥ 30.00: obese.


What causes obesity?

The most common specific causes of obesity include:

  • eating a poor diet of foods high in fats and calories;
  • having a sedentary (inactive) lifestyle;
  • not sleeping enough, which can lead to hormonal changes that make you feel hungrier and crave certain high-calorie foods;
  • genetics, which can affect how your body processes food into energy and how fat is stored;
  • growing older, which can lead to less muscle mass and a slower metabolic rate, making it easier to gain weight;
  • pregnancy (weight gained during pregnancy can be difficult to lose and may eventually lead to obesity).
  • Medical conditions which may lead to the occurrence of obesity include:
  • polycystic ovary syndrome (PCOS): a condition that causes an imbalance of female reproductive hormones;
  • Prader-Willi syndrome: a rare condition that an individual is born with which causes excessive hunger;
  • Cushing syndrome: a condition caused by having an excessive amount of the hormone cortisol in your system;
  • hypothyroidism (underactive thyroid): a condition in which the thyroid gland doesn’t produce enough of certain important hormones;
  • osteoarthritis (and other conditions that cause pain that may lead to inactivity).


Which are the health risks of being overweight?

Several conditions are linked to obesity or overweight. These conditions include:

  • Bone and cartilage degeneration (Osteoarthritis): obesity affects especially the knee joint. The risk of developing knee osteoarthritis is nine times increased in obese women.
  • Heart diseases: extra weight leads to high levels of blood pressure and cholesterol.
  • Gallbladder disease: in the case of obesity, the liver over-produces cholesterol which is delivered into the bile. Therefore, the bile becomes supersaturated, leading to the occurrence of gallstones.
  • Dyslipidaemia: the primary dyslipidaemia related to obesity is characterized by increased triglycerides, decreased HDL levels, and abnormal LDL composition.
  • Respiratory problems;
  • Several cancers: cancer of the colon, breast cancer, endometrium cancer, kidney cancer, oesophagus cancer, gallbladder cancer, ovaries cancer and pancreas cancer have been reported to be linked with obesity.
  • Gout: Gout is a disease that affects the joints. It happens when you have high levels of uric acid in your blood. The uric acid can form crystals that deposit in the joints.
  • Sleep apnoea: it represents a breathing condition that is linked to overweight. Sleep apnoea may cause a person to snore heavily and to briefly stop breathing during sleep. This condition may also cause daytime sleepiness and increases the risk of heart diseases and stroke.
  • Stroke: obesity is linked to more strokes among women aged 35 to 54.
  • Type 2 diabetes: obesity represents one of the strongest risk factors for type 2 diabetes. Most people diagnosed with type 2 diabetes are overweight or obese. Risk of developing type 2 diabetes was shown to be decreased by eating a balanced diet and becoming more physically active.


Treatment of obesity

Treatment of obesity has two main objectives:

  • Reach the healthy weight;
  • Maintain the healthy weight.

Treatment of obesity starts by changing your lifestyle, which should include:

  • Self-monitoring of caloric intake and physical activity;
  • Goal setting;
  • Stimulus control;
  • Non-food rewards;
  • Relapse prevention.

According to the Endocrine Society newly released guidelines, the treatment of obesity should include the following:

  • Diet, exercise and behavioural modification should be used in case of body mass index of 25 kg/m2 or higher.
  • Pharmacotherapy is indicated if the level of the body mass index is 27 kg/m2 or higher with comorbidity or body mass index over 30 kg/m2.
  • In case of body mass index of 35 kg/m2with comorbidity or body mass index over 40 kg/m2, bariatric surgery in indicated.
  • The comorbid medical conditions such as hypertension, dyslipidaemia, type 2 diabetes mellitus and obstructive sleep apnoea are suggested to be ameliorated.
  • Pharmacological treatment for weight loss should be continued only if the patient losses 5% or more of body weight at 3 months and the medication is considered safe for the patient.
  • In patients with type 2 diabetes mellitus who are overweight or obese, antidiabetic medications that have additional actions to promote weight loss (such as glucagon-like peptide-1 [GLP-1] analogues or sodium-glucose-linked transporter-2 [SGLT-2] inhibitors) are suggested, in addition to the first-line agent for type 2 diabetes mellitus and obesity, metformin.
  • Angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), and calcium channel blockers, rather than beta-adrenergic blockers, should be considered as first-line therapy for hypertension in patients with type 2 diabetes mellitus who are obese.

The drugs approved by the European Medicines Agency for obesity treatment are:

  • Xenical (orlistat);
  • Saxenda (liraglutide);
  • Mysimba (naltrexone, bupropion).


What is Orlistat?

Orlistat is the active substance of Xenical, a drug approved by both European Medicines Agency and U.S. Food and Drug Administration for the treatment of obesity. Orlistat was launched in the United Kingdom in 1998. Orlistat is recommended to be used together with dieting for the treatment of obese patients with body mass index greater than or equal to 30 kg/m2, or overweight patients (body mass index greater than or equal to 28 kg/ m2) who are at risk of illness because of their weight.
Orlistat is available only by prescription.


How does Orlistat work?

Orlistat acts as an anti-obesity agent by inhibiting gastrointestinal lipases (enzymes that digest fat), thereby reducing absorption of dietary fat. It exerts its therapeutic activity in the lumen of the stomach and small intestine by forming a covalent bond with the active serine site of the gastric and pancreatic lipases. Therefore, the body cannot use this dietary fat for energy and convert into fat tissue, so the weight will be reduced. Orlistat does not affect the appetite. At the recommended therapeutic dose of 120 mg three times a day, Orlistat inhibits dietary fat absorption by approximately 30%. Because some vitamins are fat soluble, the effect of Orlistat is to reduce their body absorption. Therefore, the drug should only be taken in conjunction with fatty meals, and a multivitamin tablet containing these vitamins (D, E, K and beta-carotene) should be taken once a day, at least 2 hours before or after taking the drug.


From: £51.99

Is Orlistat safe?

Like all medicines, this medicine can cause side effects, although not everybody gets them.
If you do not feel well while you are taking Orlistat, call immediately your doctor or your pharmacist.
Most of the unwanted effects related to the use of Orlistat result from its local action in your digestive system. These symptoms are generally mild, occur at the beginning of treatment and are particularly experienced after meals containing high levels of fat. Normally, these symptoms disappear if you continue treatment and keep to your recommended diet.
Very common side effects of Orlistat (may affect more than 1 in 10 people) include:

  • a headache,
  • abdominal pain/discomfort,
  • urgent or increased need to open the bowels,
  • flatulence (wind) with or without discharge,
  • oily discharge, oily or fatty stools,
  • liquid stools,
  • low blood sugar levels (experienced by some people with type 2 diabetes),
  • upper respiratory infections,
  • flu.

Common side effects of orlistat (may affect up to 1 in 10 people) include:

  • rectal pain/discomfort,
  • soft stools,
  • incontinence (stools),
  • bloating (experienced by some people with type 2 diabetes),
  • tooth/gum disorder,
  • the irregularity of menstrual cycle,
  • tiredness,
  • anxiety,
  • lower respiratory infections,
  • urinary tract infections.

Side effects with unknown frequency (frequency cannot be estimated from the available data) of Orlistat include:

  • allergic reactions: the main symptoms are itching, rash, wheels (slightly elevated, itchy skin patches that are paler or redder than surrounding skin), severe difficulty in breathing, nausea, vomiting and feeling unwell.
  • skin blistering (including blisters that burst),
  • diverticulitis (inflammation of small outpouchings along the wall of the colon),
  • bleeding from the back passage (rectum),
  • increases in the levels of some liver enzymes may be found in blood tests,
  • hepatitis (inflammation of the liver): symptoms can include yellowing skin and eyes, itching, dark coloured urine, stomach pain and liver tenderness (indicated by pain under the front of the rib cage on your right-hand side), sometimes with loss of appetite.
  • gallstones,
  • pancreatitis (inflammation of the pancreas),
  • oxalate nephropathy (build-up of calcium oxalate which may lead to kidney stones),
  • effects on clotting with anti-coagulants.

If such symptoms occur, stop taking Orlistat and tell your doctor.


Safety and efficacy of Orlistat in clinical trials

Safety and efficacy of Orlistat were assessed on eighty obese patients (BMI>30). The subjects were randomized in two groups. Group 1 received Orlistat 120 mg three times a day and group 2 received placebo three times a day. Weight, waist circumference, BMI, total cholesterol, triglycerides, HDL, LDL were measured at baseline and then at 8th, 16th and 24th week.
Various haematological and biochemical parameters were assessed for safety evaluation, also the adverse events reported by patients were recorded.
The results have shown that compared to placebo, Orlistat caused significant reduction in weight (4.65 kg vs 2.5 kg; orlistat vs placebo, respectively), BMI (1.91 kg/m2 vs 0.64 kg/m2) and waist circumference (4.84 cm vs 2 cm), cholesterol (10.68 mg vs 6.18 mg) and LDL level (5.87 mg vs 2.33 mg). In the Orlistat group, the gastrointestinal side effects like loose stools, oily stools/spotting, abdominal pain and faecal urgency were observed.
The safety profile of Orlistat was assessed in another post-marketing surveillance study. Patients were identified from dispensed prescriptions issued by primary care physicians for Orlistat between December 1998 and November 1999. The outcome data were event reports obtained by sending questionnaires (green forms) to the prescribing doctor at least 6 months after the first prescription for an individual patient.
The questionnaires of 16021 patients were analysed. The median age of the patients was 45 and 80.1% were females.
The events reported most frequently during the 1st month of treatment were ‘not effective’ (639; 4.0% of cohort), diarrhoea (371; 2.3%) and weight loss (230; 1.4%).
The incidence of some adverse events was significantly greater in the first month of treatment compared with months 2 and 3. These events included: non-specific events (e.g. intolerance, malaise/lassitude, unspecified side effects), weight loss and vaginitis/vulvitis.
Other reported gastrointestinal adverse events included diarrhoea, pain abdomen, flatulence, nausea/vomiting, rectal discharge, faecal incontinence and gastrointestinal unspecified events.
According to the results, Orlistat is well tolerated by the patients.


Precautions before taking Orlistat

Before taking Orlistat, inform your doctor or your pharmacist if you suffer or you have been suffering from:

  • Type 2 diabetes mellitus: the results of clinical trials have shown that the decrease in body weight with Orlistat treatment was less in patients with type 2 diabetes than in non-diabetic patients. The treatment with antidiabetics should be closely monitored at patients who are taking
  • Orlistat.
  • Rectal bleeding;
  • Digestive problems including chronic malabsorption syndrome;
  • Gallbladder problems (cholestasis);
  • Hypothyroidism;
  • Eating disorders such as anorexia nervosa and bulimia;
  • HIV infections;
  • Seizures;
  • Chronic kidney disease: the use of orlistat may be associated with hyperoxaluria and oxalate nephropathy leading sometimes to renal failure.

During the treatment with Orlistat, it is recommended to use an additional contraceptive method to prevent the failure of oral contraception that could occur in case of severe diarrhoea.


Contraindications of Orlistat

Orlistat is contraindicated in the following situations:

  • Hypersensitivity to the active substance or to any of the excipients;
  • Chronic malabsorption syndrome;
  • Cholestasis;
  • Breastfeeding.


Orlistat drug interactions

Before starting the treatment with Orlistat, tell your doctor or your pharmacist if you are taking or have recently taken any other medicines. Orlistat may modify the activity of the following drugs:

  • Anticoagulants;
  • Ciclosporin;
  • Iodine salts and/or levothyroxine;
  • Amiodarone;
  • Medicines to treat HIV.

Also, Orlistat reduces the absorption of supplements of some fat-soluble nutrients, particularly beta-carotene and vitamin E. You should, therefore, follow your doctor’s advice in taking a well-balanced diet rich in fruit and vegetables. Your doctor may suggest a multivitamin supplement intake for a period of time.


How should I take Orlistat?

Orlistat should be taken exactly as your doctor has indicated. The usual dose of Orlistat is one capsule taken with each of the three main meals per day. It can be taken before, during a meal or up to one hour after a meal. The capsule should be swallowed with water.
Orlistat should be taken with a well-balanced, calorie-controlled diet that is rich in fruit and vegetables and contains an average of 30 % of the calories from fat.
Your daily intake of fat, carbohydrate and protein should be distributed over three meals. This means you will usually take one capsule at breakfast time, one capsule at lunch time and one capsule at dinner time. To gain optimal benefit, avoid the intake of food containing fats between meals, such as biscuits, chocolate and savoury snacks.
Orlistat only works in the presence of dietary fat. Therefore, if you miss a main meal or if you have a meal containing no fat, Orlistat does not need to be taken.
Tell your doctor if, for any reason, you have not taken your medicine exactly as prescribed. Otherwise, your doctor may think that it was not effective or well tolerated and may change your treatment unnecessarily.
Your doctor will discontinue the treatment with Orlistat after 12 weeks if you have not lost at least 5% of your body weight as measured at the start of treatment with Orlistat.


  2. Arroyo-Johnson C, Mincey K. Obesity Epidemiology Worldwide. Gastroenterology Clinics of North America. 2016;45(4):571-579.
  3. Https://
  11. Jain S, Ramanand S, Ramanand J, Akat P, Patwardhan M, Joshi S. Evaluation of efficacy and safety of orlistat in obese patients. Indian Journal of Endocrinology and Metabolism. 2011;15(2):99.
  12. Acharya NV, Wilton LV, Shakir SA. Safety profile of orlistat: results of a prescription-event monitoring study. Int J Obes (Lond). 2006 Nov;30(11):1645-52. Epub 2006 Mar 21

Assured Pharmacy is not liable for the currency or accuracy of the information contained in this blog post. For specific information about your personal medical condition, please contact our doctors or pharmacists for advice on [email protected]