Switching from Wegovy to Zepbound

Why consider switching

Common reasons to switch: insurance formulary change, plateaued weight loss on Wegovy, intolerable side effects on Wegovy, or preference for tirzepatide's slightly stronger efficacy profile (SURMOUNT-5 head-to-head trial showed Zepbound's mean weight loss exceeded Wegovy's by several percentage points). Lilly's self-pay vial program ($349-549/mo) is also often cheaper than Novo's NovoCare ($499/mo) for cash patients.

What changes

Active ingredient changes from semaglutide (GLP-1 agonist) to tirzepatide (dual GLP-1 + GIP agonist). The added GIP activity produces stronger appetite suppression and weight loss in trials. Side-effect profile is similar but some patients report stronger GI symptoms on tirzepatide at equivalent body-weight-loss-effectiveness doses. Injection device and pen design differ.

Dose conversion

There is no exact dose-equivalence between semaglutide and tirzepatide because they hit different receptor combinations. Standard practice is to start Zepbound at 2.5mg regardless of your Wegovy dose, then titrate per Zepbound's standard schedule (2.5 → 5 → 7.5 → 10 → 12.5 → 15mg every 4 weeks as tolerated). Some clinicians starting from high-dose Wegovy will jump to Zepbound 5mg, but the safer default is to restart titration.

Transition timeline

1. 1
   Week 0

   Last Wegovy injection; clinician prescribes Zepbound.

2. 2
   Weeks 1-4

   Start Zepbound 2.5mg. Allow 1-week washout from last Wegovy if possible.

3. 3
   Weeks 5-20

   Titrate every 4 weeks toward chosen maintenance dose (typically 5-15mg).

4. 4
   Month 6+

   Steady state. Many patients see additional weight loss in months 3-6 after switching from Wegovy plateau.

What to watch for

• ·Returning GI side effects with each Zepbound dose step (you may have tolerated Wegovy fully and need to re-acclimate)
• ·Same MTC/MEN2 contraindications apply
• ·Hypoglycemia if on other diabetes medications
• ·Pancreatitis warning signs

Cost impact

Zepbound list price (~$1,060/mo) is lower than Wegovy (~$1,349/mo). LillyDirect Self-Pay vials run $349-549/mo for cash patients, often cheaper than Novo's $499/mo NovoCare. Lilly's commercial savings card can drop insured copay to as low as $25/mo for 6 months. For most cost-conscious patients, Zepbound is the cheaper option.