Orlistat is a lipase inhibitor medication approved for weight management in adults with a body mass index (BMI) of 30 or greater, or 27 or greater with other risk factors such as hypertension, type 2 diabetes, or dyslipidemia. It functions by inhibiting gastric and pancreatic lipases in the gastrointestinal tract, thereby reducing the hydrolysis of dietary triglycerides into absorbable free fatty acids and monoglycerides. This results in approximately 30% reduction in dietary fat absorption, supporting a calorie-controlled diet and sustainable weight loss when used as part of a comprehensive weight management program under medical supervision.

Features

• Contains orlistat as the active pharmaceutical ingredient
• Available in 60 mg (over-the-counter) and 120 mg (prescription-only) formulations
• Lipase inhibitor class; not systemically absorbed
• Requires three-times-daily dosing with fat-containing meals
• Typically supplied in capsules of 60 or 120 mg

Benefits

• Supports clinically meaningful weight loss when combined with a reduced-calorie diet
• Improves cardiovascular and metabolic risk profiles, including reductions in LDL cholesterol and systolic blood pressure
• Delays progression to type 2 diabetes in at-risk individuals
• Promotes long-term weight maintenance when incorporated into a structured lifestyle intervention
• Provides a non-centrally acting mechanism, avoiding effects on neurotransmitters
• Encourages adherence to dietary modifications through physiologic feedback

Common use

Orlistat is indicated as an adjunct to a reduced-calorie diet for weight management in adults with obesity (BMI ≥30 kg/m²) or overweight (BMI ≥27 kg/m²) with comorbidities. It is commonly used in individuals who have not achieved adequate weight loss through diet and exercise alone. Treatment is typically initiated alongside a medically supervised weight management program and is most effective when patients adhere to a nutritionally balanced, hypocaloric diet containing no more than 30% of calories from fat.

Dosage and direction

The recommended dosage is one 120 mg capsule taken three times daily with each main meal containing fat (up to 30% of total daily calories). Dosing may be timed during the meal or up to one hour after eating. If a meal is missed or contains no fat, the dose should be omitted. The 60 mg formulation is taken similarly but is available without prescription for adult use. Treatment should be discontinued if no meaningful weight loss (e.g., ≥5% of baseline body weight) occurs within 12 weeks.

Precautions

Use with caution in patients with chronic malabsorption syndromes or cholestasis. Monitor for potential decreases in fat-soluble vitamin (A, D, E, K) levels; a daily multivitamin supplement containing these vitamins should be taken at least 2 hours before or after orlistat administration. Not recommended for use during pregnancy or breastfeeding. Renal function should be monitored in those taking concomitant medications affected by renal impairment. Patients should be counselled on the importance of a nutritionally balanced diet to avoid gastrointestinal effects.

Contraindications

Hypersensitivity to orlistat or any component of the formulation; chronic malabsorption syndrome; cholestasis; organic causes of obesity; pregnancy and breastfeeding; concomitant use with cyclosporine or acarbose.

Possible side effects

Common gastrointestinal effects include oily spotting, flatus with discharge, fecal urgency, fatty/oily stool, oily evacuation, increased defecation, and fecal incontinence. These are generally dose-dependent, diminish with continued use, and can be mitigated by reducing dietary fat intake. Other reported effects include abdominal pain/discomfort, nausea, infectious diarrhea, headache, upper respiratory infection, anxiety, fatigue, menstrual irregularities, and dental/gum discomfort.

Drug interaction

Orlistat may reduce absorption of fat-soluble vitamins and some lipophilic drugs. Avoid concurrent use with cyclosporine (separate dosing by at least 3 hours). Monitor levels of amiodarone, warfarin (monitor INR closely), antiepileptic drugs, levothyroxine, and oral contraceptives. May enhance the hypoglycemic effect of acarbose; concomitant use is contraindicated. Can decrease plasma concentrations of antiretroviral drugs such as atazanavir and efavirenz.

Missed dose

If a dose is missed, it should be skipped and the regular dosing schedule resumed at the next meal. Do not double the dose to make up for a missed administration.

Overdose

Cases of overdose have reported increased severity of gastrointestinal effects such as abdominal discomfort, oily discharge, and steatorrhea. There is no specific antidote; treatment should be symptomatic and supportive. Maintain hydration and discontinue orlistat for several days following a significant overdose.

Storage

Store at room temperature (15–30°C/59–86°F) in a dry place. Keep in the original container, tightly closed, and protect from moisture and light. Keep out of reach of children and pets.

Disclaimer

This information is intended for medical professionals and should not replace individualized clinical judgment. Orlistat should be used only under appropriate medical supervision as part of a comprehensive weight management strategy. Patients must be evaluated for appropriate use, contraindications, and monitored for efficacy and adverse effects throughout treatment.

Reviews

Clinical trials and meta-analyses consistently demonstrate that orlistat, in combination with lifestyle modification, produces significantly greater weight loss than placebo over 1–4 years. In the XENDOS study, orlistat reduced the incidence of type 2 diabetes by 37% in obese patients with normal or impaired glucose tolerance. Real-world evidence supports its utility in motivated patients who adhere to dietary recommendations, though gastrointestinal side effects remain a common reason for discontinuation. Long-term data indicate sustained weight loss and metabolic benefits in adherent populations.