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.

Three key takeaways

• Studies show Mounjaro helps people lose a bit more weight on average (around 22.5%) compared to Wegovy (around 21%). This is often the main reason people think about switching.
• Wegovy stays in your system for a while, so it's best to leave about five weeks between stopping Wegovy and starting Mounjaro. Never take both at the same time, and always check with your prescriber first.
• Mounjaro can make oral contraception less effective, so you might need a backup method. It's also more expensive than Wegovy, which is something to consider.

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 Mounjaro side effects & Wegovy side effects 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 21% body weight on average, Mounjaro has been shown to reduce body weight by 22.5%. 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. You can then increase to the maximum dose of Wegovy 7.2mg. 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.

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.

Frequently asked questions about switching

Can you switch from the Wegovy pill back to injections?

Yes, you can. We’d advise you to wait seven days (one week) after your last Wegovy pill before you start on Mounjaro injections. Your prescriber will advise on the right dose to restart on based on where you are in your treatment.

Sources

• Tirzepatide once weekly for the treatment of obesity. (2022) Journal of the American Medical Association. [Accessed 9th July 2026].
• Efficacy and Safety of Semaglutide 7.2 mg in Obesity: The STEP UP Trial. (2025). Novo Nordisk. [Accessed 9th July 2026].