GLP-1 side effects
Most GLP-1 side effects are mild and improve with slow dose titration. Here are the most common reactions, how often they happen, and how to manage them.
Nausea
Prevalence: 20–44%Most common, typically subsides 4–8 weeks after dose changes. Eat smaller meals and avoid high-fat foods.
Vomiting
Prevalence: 5–24%Often paired with nausea, more frequent at dose increases. Slow titration helps.
Diarrhea
Prevalence: 8–30%Usually mild; stay hydrated. Persistent symptoms warrant a clinical check.
Constipation
Prevalence: 6–24%Fiber intake and hydration usually resolve.
Headache
Prevalence: 10–14%Often related to dehydration from reduced food/fluid intake.
Fatigue
Prevalence: 5–11%Common during early weeks; typically improves.
Injection-site reaction
Prevalence: ~5%Rotate injection sites; usually self-limited.
Hypoglycemia
Prevalence: Higher with concurrent insulin/sulfonylureasDiscuss with your clinician if you take diabetes medications.
Severe abdominal pain, persistent vomiting, signs of an allergic reaction, vision changes, or symptoms of pancreatitis require immediate medical attention. GLP-1s carry a boxed warning about thyroid C-cell tumors in rodent studies; patients with a personal or family history of medullary thyroid carcinoma or MEN 2 should not use these medications.
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