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The first month sets expectations. Most patients experience appetite reduction within days, GI side effects within the first week, and the first real weight loss by week 3-4.
First injection at sub-therapeutic starter dose (Wegovy 0.25 mg, Zepbound 2.5 mg, Mounjaro 2.5 mg). Nausea and mild GI effects start within 24-72 hours for ~40% of users. Appetite suppression is often noticeable by day 7. Weight change in the first 4 weeks averages 2-4 lbs (1-2% body weight).
Severe nausea or vomiting requiring medical contact. Signs of dehydration (dark urine, dizziness, headaches). Hypoglycemia symptoms if you are on insulin or sulfonylureas. Injection-site reactions beyond mild redness.
STEP-1 (Wegovy) and SURMOUNT-1 (Zepbound) both showed peak nausea incidence during titration weeks 1-12. Most users adapt; <10% discontinue in the first 8 weeks due to GI effects.
The biggest mistake new users make is treating the first 4 weeks as the steady state. The starter dose is sub-therapeutic. Real weight loss accelerates after week 8. Do not judge efficacy yet.
Editorial summary, not medical advice. Cycling, dose changes, and discontinuation should be coordinated with your prescriber.