Understanding the rankings
Best tolerability: Xenical
Xenical's side effects are the most predictable and controllable of any weight loss medication. They're entirely tied to dietary fat intake — eat low-fat meals and you'll experience minimal GI effects. Eat a greasy meal and you'll know immediately. Many patients view this as "built-in dietary accountability" rather than a traditional side effect. The medication barely enters your bloodstream, making systemic side effects essentially non-existent.
The trade-off: Xenical produces the least weight loss (3–5%).
Runner-up: Mounjaro
Despite being the most effective weight loss medication (~21% loss), Mounjaro has notably lower GI side effect rates than Wegovy. Nausea affects ~29% of Mounjaro users vs ~44% for Wegovy. Vomiting is ~12% vs ~24%. This is a significant tolerability advantage — you get more weight loss with less nausea.
Fastest side effect resolution: Contrave
Contrave's nausea typically resolves within 2–4 weeks — faster than either GLP-1 medication (8–20 weeks). If getting through the initial side effect period quickly matters to you, Contrave has an advantage here.
Most persistent side effects: Duromine
Unlike other medications where side effects improve over time, Duromine's stimulant effects (insomnia, elevated heart rate, restlessness) persist throughout the entire 12-week treatment. They don't get better because they're inherent to how the medication works.
Tips for managing side effects on any medication
- Start slow: All medications with dose escalation are designed to minimise side effects — don't rush the escalation
- Eat smaller meals: Particularly important for GLP-1 medications
- Stay hydrated: Dehydration worsens almost every side effect
- Avoid trigger foods: High-fat for Xenical, rich/greasy for GLP-1s, caffeine for Duromine
- Communicate with your doctor: They can adjust doses, extend escalation periods, or prescribe anti-nausea medication