Switching from Wegovy to Mounjaro
If you are currently taking Wegovy and thinking of switching to Mounjaro, it's important that you do your research to make an informed decision that is right for you. While there are many reasons why you may want to switch, such as if you are experiencing side effects, it’s always important to first discuss changing weight loss treatment with your prescribing clinician.
Why switch weight loss treatments?
Results
Weight loss management with the injections is an individual journey, with each treatment working differently for each patient. However, if you feel that you are not experiencing significant results, it may be time to consider a different weight loss treatment like Mounjaro.
Side effects
Even though the common side effects of both medicines are similar, i.e. headaches, nausea and vomiting, it's important to remember that they are different treatments. Although your body may not respond well to Wegovy, it does not mean it will react the same way when taking Mounjaro.
Effectiveness
Whilst recent studies have shown that Wegovy helps people lose roughly 15%-17 % body weight on average[1], Mounjaro has been shown to reduce body weight by up to 25%[2]. This has been the leading factor in most people's decision to switch.
The differences between doses for Wegovy and Mounjaro
The doses of both treatments are similar. Both are taken via a weekly injection, and each pen contains four doses. However, Wegovy comes in five different strengths compared to Mounjaro's six.
Wegovy
Starting at 0.25mg, Wegovy doses increase strength every four weeks to 0.5mg, 1mg, 1.7mg, and 2.4mg—the last of which you are encouraged to maintain. Maintaining a dose of any weight loss medication is a joint decision between you and your prescribing clinician.
Mounjaro
Like Wegovy, if you follow the titration plan, Mounjaro doses increase in strength every four weeks. However, Mounjaro continues to increase at the same increment of 2.5mg (2.5mg, 5mg, 7.5mg, 10mg, 12.5mg and 15mg).
With this treatment, maintenance dosing is slightly different. You will work directly with your prescriber to increase your dose until you find the most suitable strength for you. You will likely be advised to stay on the lowest yet still effective dose. Mounjaro maintenance doses range between 5mg and 15mg.
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How long does it take to switch from Wegovy to Mounjaro?
Semaglutide, the active ingredient in Wegovy, has a long half-life, meaning it can take a while to clear out of your system. We advise you to allow up to five weeks for this to ‘wash out’ before taking any other weight loss medication. You must remember that, as your health comes first, do not take Wegovy and Mounjaro simultaneously.
Side effects of coming off Wegovy
Stopping Wegovy may still cause side effects, as the treatment remains within your system for up to five weeks after you stop injecting. Appetite suppression will start to subside, and you may notice your hunger returning.
You may experience withdrawal symptoms such as:
- Putting weight back on
- Gastrointestinal symptoms
To reduce your likelihood of experiencing these symptoms, we recommend gradually reducing your Wegovy dosage strength before stopping the treatment.
Starting on Mounjaro
After stopping your Wegovy weight loss treatment and allowing the medicine to wash out of your system for five weeks, you are ready to start Mounjaro.
Discussing with your prescriber
The first step is to consult your prescribing clinician to discuss which dose you should start on. You will usually start from the lowest strength of the Mounjaro KwikPen, 2.5mg. While this may seem like a step backwards, it ensures that you continue your weight loss journey in the safest way possible.
Titration
Like Wegovy, Mounjaro requires you to gradually increase your dosage (known as titration). Titration can help reduce any potential side effects you may experience when starting the treatment by slowly letting your body get used to the medication.
If you do not titrate properly, and increase the strength of your dosage too quickly, or even skip strengths, this can lead to intensified side effects and could result in you becoming unwell.
Things to consider before switching
Contraception
A recent study has shown that Mounjaro can interact with oral contraception, making it less effective, whilst Wegovy currently has no known interaction. This is due to Mounjaro being both a GIP and GLP-1 receptor agonist rather than just a GLP-1 like Wegovy, making the way it works in the body slightly different.
If you are going to make the switch, then we would advise using an external form of contraception such as a condom, cap or even an implant or copper coil, which offer more reliable protection whilst on weight loss treatments. Additionally, we recommend coming off all weight loss treatment for at least two months if you have a planned pregnancy.
Cost
When looking at the weight loss injections, the starting dose of Wegovy is slightly cheaper than the starting dose of Mounjaro. However, this should not be a primary factor in your decision-making.
As mentioned earlier, the aim when on Mounjaro is to have your maintenance strength be as low as possible while still being effective. On the other hand, when maintaining on Wegovy, you will likely have to stay on the strongest dose. This could mean that switching to Mounjaro might make your weight loss journey more affordable.
