If you’ve decided to switch from Mounjaro to Wegovy, you might be worried about side effects. Will there be any new ones? And does switching cause additional discomfort?
We know starting a new treatment can be daunting. To help you navigate this change, here’s what you can expect – and how to deal with potential side effects that may arise.
Is it Safe to Switch From Mounjaro to Wegovy?
Yes, it is safe to switch from Mounjaro to Wegovy, as long as a doctor or clinician has confirmed the medication is suitable for you.
A healthcare professional will review information, like your medical history and current weight, before prescribing the medication. If you’re buying Wegovy from an online provider, you’ll have to fill in an online assessment form. For your safety, it’s important you fill in this form accurately.
When switching, you should leave a week between your last dose of Mounjaro and your first dose of Wegovy. If you take your last dose of Mounjaro on a Monday, you should not take your first dose of Wegovy until the following Monday. If possible, take it at the same time of day as your last dose.
Both Wegovy and Mounjaro follow the same dosing schedule (one injection per week, with four doses per pen).
Is Wegovy Stronger Than Mounjaro?
It can be difficult to compare the “strength” of two different medications.
Both are GLP-1 receptor agonist medications. However, the medications work in different ways and have different active ingredients. Wegovy contains semaglutide, while Mounjaro contains tirzepatide.
Some patients may find Wegovy to be more effective than Mounjaro, while others will find the opposite. In some cases, patients have reported their side effects were worse when using Mounjaro.
Clinical trials have shown that, over a period of 72 weeks, patients using the highest Mounjaro dose can expect to see an average weight loss of around 22.5%, while patients using Wegovy over 68 weeks saw an average of around 17%. Based on this, it may be safe to say Mounjaro is more effective for weight loss than Wegovy, but these are averages. Some patients will lose more on Wegovy, while some will find Mounjaro more effective.
Common Side Effects of Wegovy vs Mounjaro
The overall side effects of Wegovy are similar to the side effects of Mounjaro.
“Side effects are often similar to those experienced on Mounjaro, with things like nausea or stomach upset,” explains Abdal Alvi, Simple’s Chief Clinical Officer. “But if you have tolerated Mounjaro well, you’ll likely manage Wegovy well too.”
For Wegovy, the most common side effects include:
- Headache
- Feeling sick (nausea) or being sick (vomiting)
- Diarrhoea or constipation
- Stomach pain
- Low blood sugar (in patients with type 2 diabetes)
These are just the most common side effects. You can learn more about possible side effects by reading the Wegovy Patient Information Leaflet that comes with your medicine.
Abdal adds: “And remember, our clinical team is here to support you if you need dose adjustments or have any concerns.”
You can contact our Patient Care team by filling out this form. They can answer your questions and share your details with our clinical staff.
Are There Side Effects of Switching?
There are no known side effects of switching, beyond the side effects you might experience when you start the new medication. As both medications are GLP-1 receptor agonists, the side effects are relatively similar between them.
Some patients will switch to a higher dose of Wegovy, rather than starting on the lowest dose. In some cases, this may cause some side effects to be more severe. For many patients, switching to a higher dose should not cause any extra side effects.
If you’re on a higher dose of Mounjaro and concerned about side effects, you can choose to start on the lowest dose of Wegovy and increase your dose gradually.
How to Manage Side Effects When You Switch
When you switch weight loss injections, you’ll likely experience similar side effects to when you started your previous medication. So if you know how to manage the side effects of Mounjaro, you should know how to manage side effects on Wegovy.
To help manage the most common side effects, we recommend focusing on three key areas – nutrition, movement and mindset.
- Eat Regular Meals: Get plenty of fibre, and take the time to move throughout your day. This can help with nausea, headaches and low mood. Ideally, you will already be doing some of these. Changing your eating habits and living a healthier lifestyle will help you achieve the best results from medications.
- Drink Enough Water. Aim for 2-3 litres a day. This can help you feel much better throughout your weight loss journey.
- Take Your Dose in the Evening. This can allow you to be at home and comfortable when side effects are strong. You may even sleep through the worst of them.
As one of the most common side effects, dealing with nausea is a chief concern for many patients. If you’re experiencing nausea, ginger (including non-alcoholic ginger beer) can help settle your stomach.
How Long Does It Take My Body to Adjust to Wegovy?
In many cases, patients will adjust to Wegovy within a few weeks. Many patients say that they still experience some side effects when they increase their dose, though these can pass quickly.
Patients who start at a lower dose of Wegovy may find that the medication is not as effective as Mounjaro. This is why we allow patients to switch from Mounjaro to a higher dose of Wegovy. Patients who start at lower doses may find it takes several doses before they feel the appetite-suppressing effects and see weight loss results.
If side effects don’t go away, or they get worse, tell your provider or your GP. For additional support, our clinical team and patient care team are always here for you. Call us on 0141 774 5023.
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Key Takeaways
- Safe to Switch: Moving from Mounjaro to Wegovy is safe if you leave at least one week between doses.
- Wegovy and Mounjaro Have Similar Side Effects: Both medications can cause nausea, stomach upset, and headaches. But most patients tolerate them well.
- Focus on Lifestyle Tweaks to Manage Symptoms: Stay hydrated and eat balanced meals. Gentle movement and remedies like ginger can also help ease side effects.
- Adjustment Period: Most patients adapt to Wegovy within a few weeks. Although side effects may return temporarily when doses increase.
References
Package leaflet: Information for the patient Mounjaro KwikPen ® solution for injection in pre-filled pen Mounjaro ® (n.d.). Available at: https://www.medicines.org.uk/emc/files/pil.15481.pdf.
Package leaflet: Information for the patient wegovy FlexTouch. (n.d.). Available at: https://www.medicines.org.uk/emc/files/pil.13800.pdf.
Eli Lilly and Company. (2024). Statement: America’s leading role in biopharmaceutical innovation | Eli Lilly and Company. [online] Available at: https://investor.lilly.com/news-releases/news-release-details/statement-americas-leading-role-biopharmaceutical-innovation.
Jastreboff, A.M., Aronne, L.J., Ahmad, N.N., Wharton, S., Connery, L., Alves, B., Kiyosue, A., Zhang, S., Liu, B., Bunck, M.C. and Stefanski, A. (2022). Tirzepatide Once Weekly for the Treatment of Obesity. New England Journal of Medicine, [online] 387(3), pp.205–216. doi:https://doi.org/10.1056/nejmoa2206038.
Wilding, J.P.H., Batterham, R.L. and Calanna, S. (2021). Once-Weekly Semaglutide in Adults with Overweight or Obesity. The New England Journal of Medicine, [online] 384(11), pp.989–1002. doi:https://doi.org/10.1056/NEJMoa2032183.
Authorship
Authored by Ian Coakley
Medical Content Writer
Ian is a content writer at Simple Online Pharmacy. With a background in science communication, editing, and freelance writing, Ian aims to empower readers with accessible health information.
Medically Reviewed by Richard Wood
Pharmacist / Clinical Specialist
GPhC reg:
2078802
Richard is a pharmacist and content reviewer at Simple Online Pharmacy. He officially joined the team in 2024 after several years of working with the company as a contractor. Prior to that, he spent over 11 years as a community pharmacist, building a strong foundation in patient care.
