Background: Liraglutide 3.0 mg, with diet and exercise, produced substantial weight loss over 1 year that was sustained over 2 years in obese non-diabetic adults. Nausea was the most frequent side effect.

Objective: To evaluate routinely collected data on nausea and vomiting among individuals on liraglutide and their influence on tolerability and body weight.

Design: A randomized, placebo-controlled, double-blind 20-week study with an 84-week extension (sponsor unblinded at 20 weeks, open-label after 1 year) in eight European countries (Clinicaltrials.gov: NCT00422058).

Subjects: After commencing a 500-kcal/day deficit diet plus exercise, 564 participants (18-65 years, body mass index (BMI) 30-40 kg m(-2)) were randomly assigned (after a 2-week run-in period) to once-daily subcutaneous liraglutide (1.2, 1.8, 2.4 or 3.0 mg), placebo or open-label orlistat (120 mg × 3 per day). After 1 year, participants on liraglutide/placebo switched to liraglutide 2.4 mg, and subsequently, to liraglutide 3.0 mg (based on 20-week and 1-year results, respectively).

Results: The intention-to-treat population comprised 561 participants (n=90-98 per arm, age 45.9±10.3 years, BMI 34.8±2.7 kg m(-2) (mean±s.d.)). In year 1, more participants reported ⩾1 episode of nausea/vomiting on treatment with liraglutide 1.2-3.0 mg (17-38%) than with placebo or orlistat (both 4%, P⩽0.001). Most episodes occurred during dose escalation (weeks 1-6), with 'mild' or 'moderate' symptoms. Among participants on liraglutide 3.0 mg, 48% reported some nausea and 13% some vomiting, with considerable variation between countries, but only 4 out of 93 (4%) reported withdrawals. The mean 1-year weight loss on treatment with liraglutide 3.0 mg from randomization was 9.2 kg for participants reporting nausea/vomiting episodes, versus 6.3 kg for those with none (a treatment difference of 2.9 kg (95% confidence interval 0.5-5.3); P=0.02). Both weight losses were significantly greater than the respective weight losses for participants on placebo (P<0.001) or orlistat (P<0.05). Quality-of-life scores at 20 weeks improved similarly with or without nausea/vomiting on treatment with liraglutide 3.0 mg.

Conclusion: Transient nausea and vomiting on treatment with liraglutide 3.0 mg was associated with greater weight loss, although symptoms appeared tolerable and did not attenuate quality-of-life improvements. Improved data collection methods on nausea are warranted.