Gastrointestinal Adverse Events

Gastrointestinal Adverse Events

Gastrointestinal adverse events (GI AEs) are the most common side effects of GLP-1 receptor agonists and related incretin-based drugs. They include nausea, vomiting, diarrhea, constipation, abdominal pain and reduced appetite. They come mainly from GLP-1 receptor-driven slowing of gastric emptying and from effects on nausea and fullness pathways in the brain. GI AEs are usually worst in the first weeks of treatment and while the dose is being raised, and most are mild to moderate.

Managing GI AEs is a key part of treatment with incretin drugs. Gradual dose increases are designed to let the gut adjust to rising drug levels, which cuts how often these events happen and how severe they are. Changes to eating, such as smaller meals, avoiding high-fat foods and drinking enough fluids, can also ease symptoms. In clinical trials, GI AEs are the most common reason people stop treatment, which makes tolerability a key way competing drugs differ.

In the 48-week retatrutide Phase 2 obesity trial, nausea was the most common event: 45% of the 12 mg group and up to 60% in an 8 mg group that started at 4 mg, against 11% on placebo. Vomiting affected 19% and diarrhea 15% of the 12 mg group. These events were more common at higher doses, happened mainly while the dose was being raised and were mostly mild to moderate. Severe GI AEs were reported in 2% of participants overall, and GI events were the most common reason for stopping treatment (6% to 16% of retatrutide groups stopped for any adverse event). In the Phase 3 TRIUMPH-4 trial, nausea was reported in 43.2% at 12 mg over 68 weeks. The Phase 3 TRIUMPH program uses a refined dose escalation schedule designed to cut GI-related dropouts further while keeping the full benefit of higher doses.