Yes! You can switch from Saxenda to Mounjaro, but there are some important steps to follow to do it safely and get the best results.
Saxenda vs Mounjaro: how do they compare?
Before looking at how to switch, it helps to understand what differs between these two treatments.
Mounjaro targets two appetite-regulating hormones (GLP-1 and GIP), while Saxenda targets only one (GLP-1). Clinical trial data shows Mounjaro produces up to 21% average body weight loss, compared to around 5-10% with Saxenda. That difference is significant and it’s the main reason patients are making the switch.
Additionally, Mounjaro lasts longer so it only needs to be taken once a week and keeps a steadier effect throughout the week. Saxenda doesn’t last as long so it needs to be taken every day to keep working consistently. For many patients, the switch from daily to weekly dosing alone is a significant quality-of-life improvement.
Studies also show that between 5-10% of people discontinue Mounjaro due to side effects, compared to around 27% on Saxenda, suggesting Mounjaro is better tolerated by most patients.
How to switch from Saxenda to Mounjaro safely
Switching between weight loss injections isn’t as simple as stopping one and starting the other the same day. Because both treatments affect the same pathways, careful timing is needed to avoid overlapping effects and unnecessary side effects.
Step 1: Speak to your Prescribing Pharmacist
Before making any changes to your treatment, discuss the switch with your prescriber. They’ll review your current progress and medical history and confirm whether switching is appropriate for you. At Phlo Clinic, our Prescribing Pharmacists can assess your suitability as part of your ongoing treatment review.
Step 2: Allow a washout period
You can safely start Mounjaro after a 10 day wash-out period following your last Saxenda dose.
Step 3: Always start Mounjaro at the lowest dose
This is non-negotiable. Regardless of how long you’ve been on Saxenda or what dose you were taking, you must start Mounjaro at the lowest dose of 2.5mg once weekly. Tirzepatide is a different molecule working through a different mechanism and so your body needs time to adjust. Starting at a higher dose increases the risk of side effects, including nausea and gastrointestinal discomfort.
Step 4: Monitor how you feel during the transition
The first few weeks after switching to Mounjaro are an adjustment period while your body gets used to the new medication. During this time, it’s normal to notice some changes in appetite and digestion.
Many people feel fuller more quickly and notice less hunger or interest in snacking, especially in the early weeks or following dose titrations.
Weight loss is usually gradual at first as the starting dose is designed to help your body adjust rather than deliver maximum results straight away.
Common side effects can include nausea, constipation or diarrhoea and mild stomach discomfort, but these are usually temporary.
Our Mounjaro side effects guide covers practical tips for managing each of these in more detail.
Is Mounjaro right for you?
To be eligible for Mounjaro, you’ll usually need to meet the following criteria:
- You have a BMI of 30 or above
- You have a BMI of 27 or above alongside a weight-related health condition, such as high blood pressure, high cholesterol, or type 2 diabetes.
- The medication is considered safe for you to take, meaning you do not have any medical conditions or take any medicines that could cause problems or interactions.
- If you’re already taking a GLP-1 weight-loss medication and are switching to Phlo Clinic, you may still be eligible with a BMI of 23 or above, as long as you can provide supporting evidence of your current treatment.
For a full overview of how Mounjaro works and what to expect from treatment, see our complete Mounjaro guide.
Ready to make the switch from Saxenda to Mounjaro?
At Phlo Clinic, our prescribing pharmacists are qualified to assess your suitability, guide you through the switch and support you with monthly check-ins throughout your treatment.
References
- NHS England. Weight management injections: tirzepatide (Mounjaro). Available at: https://www.england.nhs.uk/ourwork/prevention/obesity/medicines-for-obesity/weight-management-injections/ [Accessed April 2026]
- Jastreboff AM, et al. Tirzepatide Once Weekly for the Treatment of Obesity. New England Journal of Medicine. 2022;387:205-216. Available at: https://www.nejm.org/doi/full/10.1056/NEJMoa2206038 [Accessed April 2026]
- Pi-Sunyer X, et al. A Randomized, Controlled Trial of 3.0 mg of Liraglutide in Weight Management. New England Journal of Medicine. 2015;373:11-22. Available at: https://www.nejm.org/doi/full/10.1056/NEJMoa1411892 [Accessed April 2026]
- National Institute for Health and Care Excellence (NICE). Tirzepatide for managing overweight and obesity (TA1026). Available at: https://www.nice.org.uk/guidance/ta1026 [Accessed April 2026]
- Medicines and Healthcare products Regulatory Agency (MHRA). Mounjaro (tirzepatide): authorisation for weight management in adults. Available at: https://www.gov.uk/government/organisations/medicines-and-healthcare-products-regulatory-agency [Accessed April 2026]
