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Thursday 18 June
Switching from Mounjaro to Wegovy: All You Need to Know
By Irfan Mahmud, Pharmacist & Independent Prescriber
Key Takeaways
In September 2025, the price of tirzepatide (Mounjaro) increased by 170% in the UK. As a result, many patients are now considering switching to semaglutide (Wegovy), a similar weight loss medication that is currently much cheaper.
While switching from Mounjaro to Wegovy is possible, it may be necessary to take a 7-day break between medications. You may also need to start on the lowest dose of Wegovy before working your way back up to the strongest dose.
Because there is no definitive clinical guidance on which strength dose of Wegovy you should switch to, you should always seek the advice of a medical professional before making any changes.
Mounjaro Price Increase
On 1st September 2025, the price of the weight loss injection Mounjaro increased by 170% in the UK. It could now cost upwards of £330 for a month’s supply of the strongest dose. Whether you’re a current Mounjaro patient or not, this news will understandably cause anxiety for many people.
However, the similar weight loss injection Wegovy hasn’t been subject to the same price increases. At Cuva Health, the price of a month’s supply of Wegovy ranges from £129.50 for the lowest dose (0.25 mg) to £239.90 for the strongest dose (2.4 mg).
So what is Wegovy, how does it differ from Mounjaro, and is it safe to switch between them? Let’s take a look.
Mounjaro vs Wegovy: Similarities and Differences
| Drug | Mounjaro | Wegovy |
|---|---|---|
| Average Weight Loss* | 21% | 17% |
| Mode of Action | GLP-1 and GIP agonist | GLP-1 agonist |
| Strengths | 2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg, 15 mg | 0.25 mg, 0.5 mg, 1 mg, 1.7 mg, 2.4 mg |
| Price Range | £130 – £330 | £120 – £250 |
| Dose | Once-weekly injection | Once-weekly injection |
| Common Side Effects | Nausea, vomiting, diarrhoea, constipation | Nausea, vomiting, diarrhoea, constipation |
The first thing to note about Wegovy is that it broadly works in the same way as Mounjaro: by suppressing appetite and slowing the emptying of the stomach to reduce calorie intake. The two medications are similar in a number of other ways:
- Both medications are once-weekly injections.
- A major clinical study found Wegovy to be an effective treatment for obesity. On average, users lose 17% of their starting body weight after 18 months of treatment.
- Wegovy and Mounjaro have similar side effects, the most common (affecting at least 1 in 10 people) being nausea, constipation, diarrhoea, and vomiting.
- The eligibility requirements for Wegovy are the same as for Mounjaro. Wegovy is prescribed only to patients with a BMI of 30 or higher, or with a BMI of at least 27 and a weight-related condition.
However, there are also some key differences to be aware of:
- Mounjaro works by mimicking both the GIP and GLP-1 receptors in the brain, which help regulate feelings of fullness. Wegovy only mimics the GLP-1 receptor.
- This difference may explain why Wegovy users see slightly less average weight loss than Mounjaro users. While Wegovy users lose an average of 17% of their body weight over 18 months, Mounjaro users may lose around 21%.
- Though it’s difficult to compare doses side by side, Mounjaro is generally considered a stronger medication due to its dual-action mechanism.
- Mounjaro is also more expensive than Wegovy.
Because Wegovy is a similar, safe, and effective alternative, many patients are now exploring the option of switching. But is it possible?
Can You Switch from Mounjaro to Wegovy?
In most cases, switching from Mounjaro to Wegovy is possible — but you should always consult with a medical professional first. They’ll review your medical history, previous response to weight loss medication, and current progress to ensure the switch is safe.
That said, switching is certainly feasible, provided you follow a few important guidelines.
How to Switch from Mounjaro to Wegovy
If your clinician approves the switch, here are key points to keep in mind:
- It’s generally recommended to take a break of around 7 days between the two medications — roughly the time when you’d normally take your next Mounjaro dose.
This is because it typically takes around five half-lives for a drug to reach steady state and another five half-lives for most of it to leave your system. This break helps reduce the risk of the medications overlapping. Your clinician can provide personalised advice on how long your transition period should be. - You should ideally start Wegovy on the lowest dose before gradually increasing.
If you’re worried about losing the effects of Mounjaro during this period, your clinician might consider starting you on a higher Wegovy dose — but this is usually only recommended if you haven’t experienced significant side effects.
Although it’s difficult to directly compare strengths, the table below gives a reasonable guide for safe dose transitions to help minimise side effects and maintain treatment benefits.
| Mounjaro | Wegovy |
|---|---|
| 2.5 mg | 0.5 mg or lower |
| 5 mg | 0.5 mg or lower |
| 7.5 mg | 1 mg or lower |
| 10 mg | 1.7 mg or lower |
| 12.5 mg | 2.4 mg or lower |
| 15 mg | 2.4 mg or lower |
Summary & Final Advice
Overall, the most important takeaway is to consult your clinician before switching from Mounjaro to Wegovy. While it’s possible to make the change, it’s essential to do so safely and under medical supervision.
Reviewed by Irfan Mahmud, Pharmacist & Independent Prescriber (GPhC Reg. No: 2080386)
Irfan is a UK-registered pharmacist and independent prescriber with expertise in weight management, primary care, and lifestyle medicine. As the founder of Cuva Health, he is dedicated to providing safe, clinically approved treatments and clear, trustworthy health guidance.