Switching from Wegovy to Mounjaro in the UK:
Safe Transition Guide

Both Wegovy (semaglutide) and Mounjaro (tirzepatide) are effective GLP 1 receptor agonists used for weight management. But they work differently and for some patients, that difference matters.

Common reasons patients switch from Wegovy to Mounjaro include:

• Weight loss plateau on Wegovy—progress has stalled at a lower-than-expected level
• Clinical evidence suggesting tirzepatide produces greater average weight loss
• Persistent side effects on Wegovy that may differ with a different mechanism
• Change in clinical guidance or availability from their provider

The key clinical distinction lies in receptor targets:

• Wegovy targets the GLP-1 (glucagon-like peptide-1) receptor only, reducing appetite and slowing gastric emptying.
• Mounjaro targets both GLP-1 and GIP (glucose-dependent insulinotropic polypeptide) receptors. This dual mechanism may enhance the metabolic effect compared to single-receptor agonism.

See our detailed Wegovy vs Mounjaro comparison for a full side by side breakdown.

Head to head clinical trial data and published research consistently shows greater average weight loss with Mounjaro:

Switching from Wegovy to Mounjaro requires a structured approach. Never overlap both medications they both act on the GLP 1 receptor and combining them significantly increases side effect risk.

The standard transition protocol is:

• Step 1 — Stop Wegovy: Take your final Wegovy dose and do not administer another.
• Step 2 — Wait 4–5 weeks: Allow sufficient time for semaglutide to clear your system. This washout period is important for safety.
• Step 3 — Start Mounjaro at 2.5mg: Regardless of your previous Wegovy dose, always begin at the lowest tirzepatide dose. This gives your body time to adapt.
• Step 4 — Titrate gradually: Increase the dose every 4 weeks as directed by your prescribing clinician, following the Mounjaro SmPC titration schedule.

The washout period between Wegovy and Mounjaro can feel challenging. As semaglutide clears your system, you may temporarily experience:

• Increased hunger — appetite suppression reduces as Wegovy clears
• Mild digestive changes — your gastrointestinal system adjusts
• Lower energy — a temporary effect as your body adapts
• Minor weight regain — some patients regain a small amount during the gap period

These effects typically stabilise once Mounjaro treatment begins. During the transition, focus on maintaining consistent nutrition and regular physical activity to minimise any temporary setbacks. See our guide on understanding Mounjaro plateaus for context on what to expect long term.

Always consult a healthcare provider before switching medications. This is especially important when transitioning between two prescription only treatments that act on overlapping pathways.

• Your prescribing clinician can confirm the right washout period for your specific dose of Wegovy
• Inform your GP and pharmacist about the switch so your medical records are updated
• If you experience severe nausea, vomiting, or blood sugar changes during the transition, contact your clinician promptly
• Do not attempt to self-prescribe or source Mounjaro without a valid prescription from a registered UK prescriber