GLP-1 Side Effects: What's Common vs. Rare

Short answer: the most commonly reported GLP-1 side effects are gastrointestinal, nausea, vomiting, diarrhea, and constipation, especially when starting or increasing a dose. Serious risks are much less common but are worth discussing with a provider before starting treatment.

Commonly reported side effects

• Nausea, particularly after starting or increasing dose
• Vomiting or diarrhea
• Constipation
• Stomach pain or bloating
• Fatigue

These effects are most pronounced during dose escalation, GLP-1 medications are typically started at a low dose and increased gradually, which is intended to reduce how severe these effects are.

Less common but serious risks

GLP-1 receptor agonists carry a boxed warning regarding thyroid C-cell tumors observed in animal studies, and they are not recommended for people with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2. Other reported risks include pancreatitis, gallbladder problems, and kidney issues related to dehydration from vomiting or diarrhea. This is general information, not a complete list, your provider will review the full prescribing information with you.

What determines your own risk

Individual tolerance varies significantly. A licensed provider evaluates your medical history, current medications, and other risk factors before prescribing, which is why GLP-1 medications require a prescription and medical evaluation rather than being available over the counter.