Switching from Wegovy to Mounjaro: A Guide (2024)

Wegovy and Mounjaro are injectable weight loss treatments. They’re both used to help people lose weight and maintain weight loss and should be taken alongside dietary and exercise changes that you’d normally follow as part of a weight loss plan. They’re also both taken once a week.

Wegovy contains the active ingredient semaglutide, which is known as a glucagon-like peptide-1 (GLP-1) receptor agonist. It mimics the GLP-1 hormone, which is a naturally occurring hormone released by your body after you eat. Semaglutide sends signals to your brain that you’re full, reducing your appetite and making it easier to follow a diet plan. It also slows down the emptying of your stomach, which means you’ll feel fuller for longer.

Mounjaro contains the active ingredient tirzepatide, another GLP-1 agonist that can reduce your appetite and delay the emptying of your stomach. Tirzepatide also mimics a second hormone called glucose‐dependent insulinotropic polypeptide (GIP) which is believed to further enhance the effects of GLP-1 for appetite suppression.

Semaglutide, the active ingredient in Wegovy, is also found under another name: Ozempic. This is a type 2 diabetic injection that manages blood sugar levels by helping the body produce more insulin. The media have labelled Ozempic as a weight loss drug and it can sometimes be prescribed off-label for this purpose. This is when a medication is prescribed by a doctor for a purpose other than intended, as long as it’s safe to do so. Asda Online Doctor only recommends taking UK-approved weight loss injections.

Mounjaro is also a type 2 diabetes injection found under the same name.

Find out more about the differences between Wegovy, Mounjaro, and Ozempic in our guide.

There are multiple reasons why people switch from Wegovy to Mounjaro:

• The highest weight loss results in clinical trials are for those taking Mounjaro. On the highest maintenance dose (15mg), Mounjaro helped people lose up to 22.5% of their weight after 72 weeks of treatment. On the highest maintenance dose of Wegovy (2.4mg), people lost up to 15% of their weight after 68 weeks. It’s important to note that the clinical trials didn’t run for the same amount of time and both medications are still very effective for weight loss.
• Wegovy was available in the UK before Mounjaro. Some people simply want to try the newer weight loss injection to see if their results are different or as a personal preference.
• Wegovy is an effective weight loss medication, although not every person who takes it loses the weight they want to. If this happens, your doctor may recommend switching from Wegovy to Mounjaro to see if your body reacts differently to another active ingredient.
• Some people want to try the active ingredient tirzepatide instead of semaglutide. Tirzepatide mimics 2 hormones, so although it works in the same way, this may further enhance the effects of the medication.
• Wegovy and Mounjaro both have side effects, although not everyone will get them. You may want to try Mounjaro if Wegovy is causing severe or ongoing side effects that aren’t getting better, even at lower doses. Everyone reacts differently to medications and getting side effects on one medication doesn’t mean you’ll get side effects on another.
• The demand for Wegovy in the UK has been higher than the manufacturer anticipated. Due to this, there’s been supply shortages and some people haven’t been able to increase their dose or get the maintenance dose. For this reason, some people have switched to Mounjaro, as there are more maintenance doses available and more dosage options.

“Switching from one medication to another is a personal choice that should be discussed with your doctor. You may want to switch if you’re not seeing the results you want, or if you’d rather try the active ingredient tirzepatide. Either way, it’s important to consider all options before making the switch. We can support you through the process if you want to move from Wegovy to Mounjaro.”

Dr Babak Ashrafi, Clinical Lead for Service Expansion

Switching from Wegovy to Mounjaro involves a few simple steps, but remember to always follow any specific instructions given by your doctor. Below are the steps you’ll follow if you choose to switch:

1. After discussing this option with your doctor, stop taking Wegovy when your last pen is finished. You may stop straight away if you’re switching due to side effects and don’t want to finish your medication.
2. You’ll need to wait at least 5 weeks before starting Mounjaro. This break between medications allows enough time for Wegovy to leave your system before starting a new medication.
3. Start taking Mounjaro, following the medication’s dosage schedule. Even if you were taking Wegovy at the highest dose, you’ll need to start taking Mounjaro from the lowest dose (2.5mg). If you’re happy with your Mounjaro weight loss results and you aren’t getting ongoing or severe side effects, you can continue following the dosage schedule or choose to stay at one of the lower maintenance doses.

You can switch from Wegovy to Mounjaro if you’re eligible to take both medications. Your doctor will check that you meet the following criteria:

• A body mass index (BMI) of between 27 and 30 with a weight-related condition or risk factor, such as prediabetes, or a BMI of 30 or more.
• No pre-existing or previous medical conditions that make weight loss injections unsuitable, such as an allergy to the active ingredient.
• Not pregnant or breastfeeding.
• Not taking any medication that could interact with these weight loss injections and cause severe side effects.
• Over 18 years old.