How to Switch from Wegovy to Mounjaro

Weight loss injections have become a popular treatment for obesity, 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 side 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. Please note that when switching using our dose conversion guide, you may not experience the same effect (which can improve with dose titration), as the treatments are not necessarily medically equivalent.

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 but Mounjaro contains tirzepatide and, although both can potentially cause side effects, your body may tolerate one better than the other.

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 21% using Wegovy at the highest maintenance dose over 72 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.

Who can switch from Wegovy to Mounjaro?

You can switch under the guidance of a doctor if you meet the following prescribing guidelines:

• over 18 years old
• 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

If you are already prescribed Wegovy, you are likely to be able to use Mounjaro. You may be able to switch even if you've reached a healthy BMI of 25 or lower.

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 you are thinking about switching from Wegovy to Mounjaro and you are:

New to our service: Make an account with us and request treatment for Mounjaro. You’ll need to fill in a short questionnaire, and one of our doctors will assess your eligibility and medical history to check whether Mounjaro is suitable for you.

Already a patient with us: Fill in a health questionnaire and let us know that you want to switch. In most cases, if you are eligible for Wegovy, you will be eligible for Mounjaro too, but our doctors always check if a treatment is safe for you.

If your request is approved, you will 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 7 days to allow Wegovy levels to lower in your system before starting Mounjaro.
3. After 7 days, start your first Mounjaro dose.

What is the criteria for qualifying for Mounjaro?

For doctors to prescribe 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

These BMI requirements are the same for Mounjaro as Wegovy, so you’ll likely be able to take both, but a doctor will make sure before prescribing.

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

Your doctor will assess which dose of Mounjaro to start you on, depending on which dose of Wegovy you are currently on or were previously taking. For instance, if you are taking 1mg of Wegovy or less, you’ll start on the first dose of Mounjaro, which is 2.5mg. If you are taking 1.7 or 2.4mg of Wegovy, you can usually start on 5mg of Mounjaro.

Mounjaro is thought to have a more potent effect because it mimics 2 hormones instead of 1, so it’s not safe to start on a higher dose, as your body needs to get 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. There is only a 7-day switching period, which is the same amount of time you wait between taking your weekly injections, so you should not notice much of a change. You may get side effects when you start Mounjaro, but this is not withdrawal symptoms.

When you switch from Wegovy to Mounjaro, you may notice several changes as Wegovy leaves your system. For example:

• a change in appetite
• side effects caused by taking a new treatment

You may notice some appetite changes because Mounjaro needs to build up in your system, especially because you’ll start on a lower dose. This is not anything to worry about and will be a temporary effect. As you continue with 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 should not experience any withdrawal symptoms when you switch from Wegovy to Mounjaro, especially as the switching period is only 7 days.

Just like Wegovy, Mounjaro can cause side effects, although not everyone will get them. Some common Mounjaro side effects that may be likely when you start taking it 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 and go away completely. Some people get 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 on our service, you will need to wait at least 7 days between your last Wegovy dose and your first Mounjaro dose.

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 21% of their body weight in 72 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.