GLP-1 Guides
GLP-1 Side Effects Guide
Every common side effect on Ozempic, Wegovy, Mounjaro, and Zepbound — when in your dose cycle it peaks, how long it typically lasts, and what the evidence says actually helps.
Why timing matters
Most GLP-1 side effects are tied to when drug levels peak — around Day 1–2 post-injection for both semaglutide and tirzepatide. Understanding the cycle helps you predict rough days and plan around them.
Nausea
Most common, usually temporary
Ozempic · Wegovy · Mounjaro · Zepbound
Peaks
Day 1–3
→Vomiting
Less common, follows nausea pattern
Ozempic · Wegovy · Mounjaro · Zepbound
Peaks
Day 1–3
→Diarrhea
Often eases in 8–12 weeks
Ozempic · Wegovy · Mounjaro · Zepbound
Peaks
Day 1–4
→Constipation
Can be persistent — manage proactively
Ozempic · Wegovy · Mounjaro · Zepbound
Peaks
Day 3–7
→Fatigue
Often tied to reduced caloric intake
Ozempic · Wegovy · Mounjaro · Zepbound
Peaks
Day 1–3
→Injection site reactions
Mild redness or firmness, resolves in 1–3 days
Ozempic · Wegovy · Mounjaro · Zepbound
Peaks
Day 0–2
→Headache
Usually dehydration-related
Ozempic · Wegovy · Mounjaro · Zepbound
Peaks
Day 1–3
→Very low appetite
The intended effect — nutrition still matters
Ozempic · Wegovy · Mounjaro · Zepbound
Peaks
Day 1–7
→Where are you in your dose cycle?
Your drug level right now tells you a lot about why you feel the way you do.
Check your drug level →What to expect at your dose
Side effect patterns vary by dose. See what the clinical trials show for where you are.
See your phase guide →Information is evidence-informed and based on published clinical trial data. Not medical advice — always discuss symptoms with your healthcare provider.