GLP-1 Side Effects

Side effects on GLP-1 receptor agonists are common, mostly gastrointestinal, dose-dependent, and largely resolve. Knowing which symptoms are normal vs which warrant medical attention is the difference between successful long-term therapy and unnecessary discontinuation.

Common side effects (>10% of patients)

• Nausea — most common. Peaks within 1–2 weeks of each dose escalation, then declines.
• Constipation — slowed GI transit. Hydration, fiber, gentle laxatives if needed.
• Diarrhea — some patients experience loose stools, especially early.
• Decreased appetite — this is the mechanism, not a side effect to "fix." Ensure adequate protein and nutrient intake.
• Vomiting — less common; concerning if persistent.
• Heartburn / reflux — delayed gastric emptying can worsen GERD.

Concerning symptoms — call your prescriber

• Severe persistent abdominal pain (especially radiating to back) — possible pancreatitis. Stop, evaluate urgently.
• Severe vomiting with inability to keep liquids down — dehydration and AKI risk.
• Severe constipation with bloating and inability to pass gas — possible ileus.
• Right-upper-quadrant pain with fever — possible gallbladder disease.
• Vision changes — uncommon but reported.
• Severe depression or suicidal thoughts — investigated but not established as causal; report regardless.

Managing nausea — what works

• Smaller, more frequent meals. Don't try to eat large meals.
• Avoid greasy/fatty foods, alcohol, very sweet foods.
• Eat slowly. Hydrate consistently — small frequent sips.
• Bland foods during titration weeks.
• Ondansetron (Zofran) prn if needed; discuss with prescriber.
• Slow the titration if needed.

The "GLP-1 face"

Rapid weight loss from any cause produces facial volume loss. Remedy: slow the weight loss rate, ensure adequate protein, consider volumizing treatments once weight stabilizes.

Muscle loss

Rapid weight loss reduces lean mass in ~70:30 (fat:lean) ratio under typical conditions. Resistance training + protein (1.6–2.0 g/kg target weight) shifts this favorably. Not optional for patients over 40.

Side effects that get better, side effects that don't

Most GI side effects improve once dose is stable. Some effects — reduced appetite, reduced alcohol tolerance, food-noise reduction — persist as long as the drug is continued. These are mechanism, not toxicity.