What over-the-counter (OTC) weight loss medications have evidence supporting their use?

Over-the-Counter Weight Loss Medications with Evidence

Orlistat (Alli) is the only FDA-approved over-the-counter medication for weight loss with substantial evidence supporting its efficacy, producing modest weight loss of approximately 3 kg over 12 months when combined with lifestyle modifications. 1, 2

Mechanism and Efficacy of Orlistat

• Orlistat works by inhibiting gastrointestinal lipases, decreasing fat absorption from the gastrointestinal tract by approximately 30% 1
• Available over-the-counter as Alli at a 60 mg dose (taken three times daily with meals containing fat) 2
• Produces modest weight loss of approximately 2.89 kg at 12 months compared to placebo when combined with dietary interventions 1
• Most weight loss occurs in the first 6 months of treatment 2

Proper Usage of Orlistat

• Should be taken with each meal containing fat (maximum 3 capsules daily) 2
• Must be used with a reduced-calorie, low-fat diet and exercise program 2
• A multivitamin should be taken once daily at bedtime when using orlistat to prevent potential nutrient deficiencies 2
• Appropriate for adults with BMI ≥27 kg/m² with obesity-related comorbidities or BMI ≥30 kg/m² 1

Side Effects and Considerations

• Common side effects include abdominal pain, oily spotting, fecal urgency, and flatulence 1
• Gastrointestinal side effects are more pronounced when consuming high-fat meals 1
• Contraindicated in patients with chronic malabsorption syndrome or cholestasis 1
• May reduce absorption of fat-soluble vitamins (A, D, E, K), necessitating supplementation 2

Monitoring and Expectations

• If response is insufficient (<5% weight loss after 3 months) or if there are significant safety or tolerability issues, the medication should be discontinued 1
• Efficacy and safety should be assessed at least monthly for the first 3 months of treatment 1
• Weight regain is common after discontinuation; continued lifestyle modification is essential 2

Other Considerations

• No other over-the-counter medications have FDA approval or substantial evidence supporting their use for weight loss 1
• Weight loss medications should always be used as adjuncts to diet, physical activity, and behavioral counseling 1, 3
• For patients who struggle with weight loss despite lifestyle modifications, prescription medications may be considered under medical supervision 1
• Close follow-up, ideally every 4-6 weeks, enables clinicians to support lifestyle changes and address adverse effects 1

Clinical Pitfalls to Avoid

• Avoid using orlistat without concurrent lifestyle modifications, as it is significantly less effective without dietary changes 3
• Do not exceed the recommended dosage (maximum 3 capsules daily) as this increases side effects without improving efficacy 2
• Be aware that many weight loss supplements sold over the internet lack evidence for efficacy and safety, and may be used without medical supervision 4
• Recognize that pharmacotherapy alone, without behavior modification, is not effective; patients typically regain weight when the drug is discontinued 4