From Wegovy to Mounjaro: What to expect when making the switch

While it can be a controversial topic, there's no denying that weight loss medications can be life-changing for those who are eligible for them.

For many, it feels like a huge weight off their shoulders when after endless unsuccessful attempts with diet and exercise, they finally find something that works for their bodies.

That said, finding the right treatment option isn't always a case of 'one and done.' There are now several different types of weight loss injections available on the market, and it can be a process of trial and error to find the one that is best suited to you.

Whether you're struggling with the side effects or you're not losing weight as quickly as you might like, there are many reasons you may decide to switch from Wegovy to Mounjaro (or vice versa). While it is possible to do so in some cases with the guidance of a medical professional, there are important considerations to keep in mind.

Read on for everything you need to know about switching from Wegovy to Mounjaro, safely and effectively.

What are the main differences between Wegovy and Mounjaro?

As Wegovy and Mounjaro are both part of a class of medications called GLP-1 (glucagon-like peptide agonists) they work in a similar way to help patients lose weight.

Both mimic the effect of the hormone GLP-1 which is naturally released in the pancreas when we eat, signalling to the brain that you're full [1].

This, in turn, can lead to weight loss, as users tend to eat smaller portions and have fewer cravings between meals. Another similarity is that Wegovy and Mounjaro are both injectable medications that are administered once a week.

However, Wegovy and Mounjaro are ultimately different drugs, and they are approved for different purposes.

Wegovy is the brand name for the active medication semaglutide, which is manufactured by the US company Novo Nordisk. It's the same medication as Ozempic — however unlike the diabetes drug, it has been approved specifically for weight loss.

Meanwhile, Mounjaro is an injectable medication used to treat type 2 diabetes, which also has the side effect of weight loss.

It uses the active ingredient tirzepatide which is a 'twincretin' — meaning, it mimics GIP (a hormone that regulates lipid handling in the intestine), as well as GLP-1. Working together, these hormones are particularly effective in helping regulate blood sugar levels in the body [2].

Wegovy and Mounjaro also have different dosing schedules, eligibility criteria, and side effects — as we'll explore in this article.

Can you switch from Wegovy to Mounjaro?

It's important to note that Wegovy and Mounjaro are not interchangeable as weight loss treatments. You cannot switch between the two (for example, take Wegovy one week or Mounjaro the next), or use both at the same time.

They also have different eligibility criteria. In the UK, Wegovy can be prescribed to those with a body mass index (BMI) over 35, who have a weight-related health condition such as pre-diabetes or high blood pressure.

Another important eligibility factor is that patients have attempted to lose weight through conventional methods such as diet and exercise and it hasn't worked.

Meanwhile, Mounjaro can be prescribed to people who are living with obesity and have a body mass index (BMI) score of 30 or more; or have a BMI score of 27-30, but also have another weight-related medical condition, such as pre-diabetes, high blood pressure, heart problems, or high cholesterol [11].

Wegovy and Mounjaro also have different dosing schedules, which is another key reason you can't take them interchangeably.

Wegovy has a fixed titration schedule: starting at 0.25 mg for 4 weeks, 1.0 mg for 4 weeks, 1.7 mg for 4 weeks, and ultimately working up to the maintenance dose of 2.4 mg [4].

Meanwhile, Mounjaro has a higher starting dose of 2.5 mg. It is also more flexible, in that it's increased in 2.5 increments every 4 weeks as needed, with a maximum maintenance dose of 17 mg [5].

If you were to switch from one medication to the other, you would need to start on the lowest dose — even if you were previously one the highest dose of the other medication.

Common reasons to switch weight loss medications

Here are some of the factors that can play a role in switching from Wegovy to Mounjaro, or any other weight loss treatment.

Side effects

It's important to note that all weight loss drugs have some side effects. However, these can vary amongst medications.

Common side effects in Wegovy include gastrointestinal symptoms like nausea, vomiting, diarrhoea, constipation, indigestion, and stomach pain [6].

Meanwhile, Mounjaro has similar side effects, but may also be accompanied by symptoms that are more typical of a GLP medication. For example, hypoglycaemia, gallbladder issues, injection site reactions, fatigue, and dizziness are all slightly more common in Mounjaro than in Wegovy [7].

At the end of the day, medications affect everyone differently.

Some can experience unpleasant side effects on Mounjaro but none on Wegovy — while, for others, the opposite can be true.

That's why it's so crucial to work alongside a healthcare professional to find the right option for you.

Effectiveness

Both Wegovy and Mounjaro have been found to be highly effective in achieving significant weight loss. However, there is some evidence that Mounjaro may have a slight advantage.

While the two have not been directly compared in studies, clinical trials have found people with diabetes taking the highest dose of Mounjaro lost 15.7% in 18 months [8].

Meanwhile, in a different study, people with diabetes lost 9.6% of their body weight on Wegovy within a similar timeframe [9].

That is likely due to Mounjaro's dual-action mechanism for regulating blood sugar. However, more research needs to be conducted to determine if the same enhanced weight loss results occur in those without diabetes.

Cost and availability

Due to supply and demand, the availability of weight loss medications can fluctuate, often due to shortages.

Therefore, someone may choose to switch between weight loss medications to make it more affordable.

Using a reputable, medically-assisted weight loss service like Juniper can help ensure you have reliable access to your weight loss medication, at a stable price.

How to safely transition from Wegovy to Mounjaro

So, you've decided that Mounjaro is a better fit for your needs, and are ready to make the switch. What happens next?

Your healthcare provider will provide you with a treatment plan with instructions on how to change medications, without missing a beat. However, if you need a refresher, this is what the process normally entails:

How to stop Wegovy

After taking the last dose of Wegovy, cease your weekly injections. You should wait at least 5 weeks before starting Mounjaro, as it can take this amount of time for the medication to leave your body, and it can be unsafe to double up.

How to start Mounjaro

First, if you haven't already, check your eligibility through Juniper. If you have the green light, your clinician will organise for your new medication to coincide with the end of that 5-week period.

Then, you'll choose your desired injection day (this should be the same day every week) and follow your dosing schedule to titrate up to your maintenance dose.

Will you experience withdrawal symptoms between treatments?

Thankfully, there are no withdrawal symptoms typically associated with stopping weight loss medications like Mounjaro and Wegovy.

That said, if you have diabetes, it can be dangerous to abruptly stop taking Mounjaro as it can cause a rebound effect on your blood sugar levels [10].

You'll also be glad to hear that you may still experience some of the appetite suppression effects during the 5-week transition period when switching from Wegovy to Mounjaro.

However, it's still important to keep up with positive habits such as following a balanced diet. Juniper's Weight Loss Programme combines injectable weight loss medications with coaching — giving you the lifelong skills you need to sustain your results for life.

Ultimately, switching from Wegovy to Mounjaro (or, the opposite) is a personal choice, and there's no one medication that's right for everyone.

While it's important to give any chronic weight management treatment enough time to work, you know your body best. If you're ready to set yourself up for long-term success, speak to your clinician or get started with Juniper's Weight Reset Programme here.

Image credit: Pexels/George Milton