How to Switch from Wegovy to Mounjaro

Weight loss injections are a popular weight loss medication, particularly Wegovy and Mounjaro. Because Mounjaro is currently the most effective weight loss injection available, many people are keen to switch over from Wegovy. Switching medications can also be suitable if you have been experiencing Wegovy side effects. Because Mounjaro contains a different active ingredient, you may find that you tolerate it better than Wegovy, experiencing fewer adverse effects.

If you wish to switch from Wegovy to Mounjaro for weight loss, this guide will tell you all you need to know, including the benefits of switching, how you can do it safely, and what to expect.

Both Wegovy and Mounjaro are approved medications for weight loss in the UK. However, Mounjaro has been proven to be more effective for weight loss, resulting in an average 22.5% weight loss over 72 weeks at the highest maintenance dose compared to 15% using Wegovy at the highest maintenance dose over 68 weeks.

Although both Wegovy and Mounjaro are glucagon-like peptide-1 (GLP-1) receptor agonists which help you lose weight by mimicking the effects of the naturally occurring hormone GLP-1, Mounjaro also mimics the effects of another digestive hormone: glucose-dependent insulinotropic polypeptide (GIP). This dual action is thought to help increase the overall effectiveness of tirzepatide, the active ingredient in Mounjaro.

Because Mounjaro is the newest weight loss injection available in the UK, you may have already started your treatment with Wegovy and be keen to switch to Mounjaro to see if it can increase your weight loss, especially if you’re not getting the results you initially expected with Wegovy.

Alternatively, if you’ve experienced any Wegovy side effects, you may want to try Mounjaro to see if your body tolerates it better. Wegovy contains the active ingredient semaglutide whereas Mounjaro contains tirzepatide and, although both can potentially cause side effects, your body may tolerate one better than the other.

Who can switch from Wegovy to Mounjaro?

You can switch from Wegovy to Mounjaro if you still meet the criteria for weight loss injection treatment.

If you are already prescribed Wegovy, you are likely to be able to use Mounjaro. However, you can only switch under the guidance of a doctor, who will check that you meet the following eligibility criteria before helping you switch:

• over 18 years old
• a body mass index (BMI) between 27 and 30 and a weight-related health condition like high blood pressure, prediabetes, or obstructive sleep apnoea, or a BMI of 30 or more
• no pre-existing health conditions that would make Mounjaro unsuitable for you, such as an allergy to tirzepatide
• not currently taking any medications, prescription, over-the-counter, or herbal, that may interact with Mounjaro
• not currently breastfeeding or pregnant

Several simple steps are involved in switching from Wegovy to Mounjaro. But first you must discuss switching medications with your doctor, so they can assess if it is safe and suitable for you to do so.

If it is, you’ll need to:

1. Stop taking Wegovy after your last pen is finished. If you are getting side effects and would prefer not to continue Wegovy treatment, you can stop immediately.
2. Wait at least 5 weeks to allow Wegovy to fully leave your system before starting Mounjaro.
3. After 5 weeks, start your first Mounjaro dose – this will be the lowest 2.5mg dose – and then follow the usual Mounjaro dosage schedule until you reach the most suitable maintenance dose for you.

It doesn’t matter what Wegovy dose you were on when you switched to Mounjaro, you’ll always need to start with the lowest Mounjaro dose. This is because Mounjaro and Wegovy contain different active ingredients, so to reduce the risk of side effects, it’s best to start on the lowest dose and slowly increase it up to the most tolerable dose.

What is the criteria for qualifying for Mounjaro?

To qualify for Mounjaro treatment, you will need to have a BMI of:

• 30 or more
• 27 or more and a weight-related health condition such as high blood pressure

The criteria for qualifying for Mounjaro is the same as Wegovy, so you’ll likely be eligible for both but a doctor will make sure before prescribing.

Can you switch from Wegovy to Mounjaro on a higher dosage?

No, when you switch from Wegovy to Mounjaro you will start your treatment on the lowest dose of Mounjaro, even if you were on the highest Wegovy dose. This is to reduce side effects as your body gets used to the new medication.

Do you get withdrawal symptoms if you switch from Wegovy to Mounjaro?

No, you should not experience withdrawal symptoms when you switch from Wegovy to Mounjaro. You may notice changes in your appetite as Wegovy leaves your system, but these will only be temporary until you start Mounjaro.

When you switch from Wegovy to Mounjaro, you may notice several changes as Wegovy leaves your system. For example, as Wegovy leaves your body, semaglutide will no longer bind to the GLP-1 receptors in your brain, so you may notice that your appetite increases.

This isn’t anything to worry about and will be a temporary effect until you begin Mounjaro treatment. Once you start Mounjaro injections, tirzepatide will bind to the GLP-1 and GIP receptors in your brain which will signal that you are full, so your appetite will reduce.

You shouldn’t experience any withdrawal symptoms when you switch from Wegovy to Mounjaro, but you may notice body changes or an upset stomach. These are just signs that your body is returning to its baseline.

Just like Wegovy, Mounjaro can cause side effects, although not everyone will get them. Some common Mounjaro side effects include:

• feeling sick (nausea)
• being sick (vomiting)
• diarrhoea
• constipation
• stomach pain

As your body gets used to Mounjaro, these side effects should become more manageable or may go away completely. Some people experience temporary side effects as their dose increases. However, as your dose goes up and you get used to tirzepatide, you should notice better weight loss results.

Can you alternate between Wegovy and Mounjaro?

No, you cannot continuously alternate between Wegovy and Mounjaro or inject both medications as part of a treatment plan. However, you can make a permanent switch from one to the other under the guidance of your doctor or a registered health professional.

To switch from Wegovy to Mounjaro, you will need to wait at least 5 weeks between your last Wegovy dose and your first Mounjaro dose, to allow the active ingredients to completely leave your system. This is essential and if you do not wait, this is the same as taking both medications at the same time, massively increasing the risk and severity of side effects. If you take Mounjaro earlier than 5 weeks after your last Wegovy dose, speak to your doctor straight away.

Is Mounjaro stronger than Wegovy?

It is not that Mounjaro is a stronger medication than Wegovy, but the active ingredient in Mounjaro, tirzepatide, has a dual action because it binds to the receptors of 2 digestive hormones, making it more effective for weight loss.

For example, over 72 weeks, people taking the highest maintenance dose of Mounjaro can lose up to 22.5% of their starting body weight, whereas people on the highest Wegovy maintenance dose can lose up to 15% of their body weight in 68 weeks.

Can I get Mounjaro on the NHS for weight loss?

Yes, but you will need to be referred by your doctor. Mounjaro has recently been approved for weight loss on the NHS, but it will be rolled out gradually, potentially over 12 years to meet the demand. However, your doctor won’t be able to prescribe Mounjaro to you, instead, they will need to refer you to a specialist weight management service who will assess if you meet the necessary criteria needed to get Mounjaro on the NHS.

Mounjaro is available on a private prescription for qualifying people and can be requested from Superdrug Online Doctor.

Can I get Wegovy on the NHS for weight loss?

Yes, Wegovy is available on the NHS for weight loss, but you must be referred to a specialist weight management service to get it and meet the following criteria:

• a BMI of at least 35 or 32.5 if you’re of Asian, Chinese, Middle Eastern, Black African or African-Caribbean origin
• a BMI between 30 to 34.9, or 27.5 to 32.4 if you're of Asian, Chinese, Middle Eastern, Black African or African-Caribbean origin, and you meet other criteria required to be treated by a specialist weight management service

You will need to make an appointment with your doctor to discuss weight loss treatments on the NHS, including Wegovy.