In the evolving landscape of weight-loss injections, many patients in the UK are considering switching from Mounjaro to Wegovy due to rising costs, limited availability, or new clinical preferences.
In this guide, we will help you compare the benefits, understand the dosing differences, and ensure a safe switch. With clear advice and ongoing support, we aim to make your journey towards sustainable weight loss as smooth as possible.
Difference Between Mounjaro and Wegovy
Mounjaro (tirzepatide) and Wegovy (semaglutide) are both once-weekly injectable treatments classified as GLP-1 receptor agonists, helping to reduce appetite and slow gastric emptying. While they share similarities as GLP-1 receptor agonists, Mounjaro shares a distinct advantage of being a dual agonist targeting both GLP-1 and GIP receptors.
Clinical evidence highlighting the difference:
- Mounjaro (tirzepatide): In the SURMOUNT-1 trial, participants without diabetes achieved an average weight loss of up to 22.5% of body weight over 72 weeks at the highest dose (15 mg).
- Wegovy (semaglutide): In the STEP-1 trial, participants without diabetes reported an average weight loss of about 14.9% of body weight over 68 weeks when combined with lifestyle changes.
Both medications can cause gastrointestinal side effects such as nausea, constipation, or fatigue. However, because Mounjaro acts on two hormonal pathways, some patients may experience more pronounced side effects compared to Wegovy.
Mounjaro Price Increase
As of 1 September 2025, the manufacturer Eli Lilly raised UK private prices for Mounjaro by up to 170%, moving from around £122 to £330 for the highest dose. While NHS patients remain protected under separate agreements and continue paying the previous pricing rates, private patients now face a substantial financial burden.
This cost surge has made long-term treatment financially challenging for many patients and prompted consideration of more affordable alternatives like Wegovy.
Mounjaro Shortage UK
Following the recent price increase, patients across the UK have also faced significant shortages of Mounjaro. Eli Lilly paused supplies, and wholesalers faced allocation limits, leading to stock outages across major chains, causing difficulty for patients to continue treatment consistently.
The combination of higher costs and supply constraints has created uncertainty for patients relying on Mounjaro. In some cases, individuals have had to delay their treatment, while others are now considering switching to Wegovy, which remains more widely available and comparatively more affordable.
Why are Patients Switching from Mounjaro to Wegovy?
Demand for Wegovy has increased sharply as a result, with some reports noting a surge of more than 2,500% in UK orders following the announcement of Mounjaro’s price hike. For patients switching, there is a need for seeking professional guidance before making changes to their treatment plan, especially when transitioning between medications with different mechanisms and dosing schedules.
Medical Consultation
Our healthcare professional will assess your current Mounjaro dosage, tolerance, and treatment goals.
One-Week Transition Period
The commonly advised one-week gap between the last Mounjaro dose and starting Wegovy is reflected in UK clinical guidance and pharmacy advice, though it is not directly sourced from Eli Lilly publications.
Some UK clinics note that Eli Lilly has suggested a longer 30-day gap to minimise overlapping side effects, but in practice, a 7-day interval is more widely adopted.
Starting Dose of Wegovy
Depending on your Mounjaro dose and tolerability, your Wegovy starting dose may be higher than the standard initial dose, though typically slightly lower than an equivalent strength to help ease the switch.
Titration and Monitoring
Wegovy dosing is gradually increased, e.g., 0.25 mg to 0.5 mg to 1 mg to 1.7 mg to 2.4 mg maintenance, depending on tolerance and therapeutic response. You’ll be monitored for side effects and progress.
Support and Follow-Up
Batley Pharmacy ensures ongoing support during and after the switch, including dosage guidance, lifestyle advice, and side-effect management.
By following these standard protocols, the Switch from Mounjaro to Wegovy can be smooth and safe.
Conclusion
At Batley Pharmacy, we understand the pressures many patients face: rising costs, uncertain supply, and treatment decisions. Our aim is to support you with clear guidance on how to switch from Mounjaro to Wegovy, ensuring safety, continuity, and value through expert clinical supervision. Reach out to our prescribing pharmacy team to discuss your personalised plan and continue confidently toward your weight-loss goals.
FAQs
Side-effects vary individually. Mounjaro’s dual-hormone action may lead to stronger effects, but both drugs can cause similar symptoms, like nausea, and tolerability depends on the person.
Yes, under clinical guidance you may begin a higher than the usual starting dose of Wegovy, based on your current Mounjaro dose and side-effect profile.
Mounjaro shows slightly greater average weight-loss in trials (22%) compared to Wegovy (17–21%), but individual response and safety profile matter in clinical decisions.
Yes, switching is safe when overseen by a healthcare professional, ensuring there is no overlap and side-effect risks are minimised.
No specific foods or medications must be avoided. Monitor for new triggers and maintain your existing diet and exercise routine.
Main reasons include steep private price increases for Mounjaro, supply shortages, and Wegovy’s comparatively lower cost and greater availability.
You should not overlap treatments; a one-week interval between your last Mounjaro dose and your first Wegovy dose is recommended.
Wegovy averages between £85–239.99 per month, substantially lower than Mounjaro, which has increased to £270–£330 per month for higher doses.
Access to Mounjaro via NHS began in mid-2025 but remains limited regionally. Wegovy could be available privately and may gain broader NHS access later, subject to NICE and NHS commissioning guidance; currently, access remains predominantly private.