The first 7 days set the trajectory. Here's the realistic expectation for symptoms, lifestyle, and what to flag.
About this article
Reviewed byDr. J. Bottoni, M.D.
RoleEditor-in-Chief, Medicine
First publishedMay 20, 2026
Last reviewedMay 20, 2026
Page typeIn-depth editorial guide
Sources15+ cited sources
Day 1 — injection day
Take your first 0.25 mg semaglutide or 2.5 mg tirzepatide dose in the morning or evening (consistent each week). Most patients feel nothing immediately. Some report mild nausea within hours.
Days 2–4 — peak nausea window
Nausea, if it appears, typically peaks days 2–4. Strategies: small meals every 3–4 hours, low-fat foods, hydrate consistently, avoid alcohol.
Days 5–7 — stabilization
Symptoms typically ease. Appetite reduction begins to be noticeable. Most patients can resume normal eating patterns by day 5–7.
What to flag
- Vomiting that limits fluid intake.
- Severe abdominal pain.
- Injection site reaction beyond mild redness.
What's normal
- Mild nausea, especially with rich/greasy food.
- Reduced appetite — this is the mechanism working.
- Constipation starting.
- Slight injection site soreness for <24h.