Switching from Mounjaro to Wegovy

Yes, it is generally safe to switch from Mounjaro (tirzepatide) to Wegovy (semaglutide), as long as it is approved by a doctor or pharmacist.

Both medications work in a similar way to support weight loss, but your prescriber will assess whether Wegovy is suitable for you, before making the switch.

If you already meet the eligibility criteria for Mounjaro, you are likely to qualify for Wegovy too.

You must leave at least 7 days between your final Mounjaro injection and your first Wegovy dose to allow your body time to adjust safely.

Step 1: Medical review and reason for switching

Discuss why you are switching, for example side effects, plateaued weight loss, product availability or cost.

We will assess your current dose, duration on Mounjaro, and weight stability.

Step 2: Washout period

You should not overlap Mounjaro and Wegovy.

Mounjaro stays in your system for a while, so you will need to wait 7 days before you can start using Wegovy.

A longer gap may be recommended if you were on a higher Mounjaro dose or experienced side effects.

Step 3: Starting Wegovy

Your prescriber will start you on the equivalent Wegovy dose.

You will need to take this dose, 7 days after having used Mounjaro.

Step 4: Managing side effects

Expect possible temporary gastrointestinal symptoms again, even if you tolerated Mounjaro well.

Eat smaller meals, avoid high-fat foods, and stay hydrated to manage nausea.

Step 5: Monitoring and follow-up

Regularly check your weight, blood sugar levels (if diabetic), blood pressure, and side effects.

You may notice that your appetite has increased slightly, but this should settle as your treatment is adjusted.

Step 6: Avoid restarting Mounjaro later without medical input

Your body responds differently to each medication, so going back or alternating between different treatments can cause stronger side effects.

Step 7: Supportive habits

Continue healthy eating, hydration, and activity to maintain results during the adjustment phase.

If dizziness, low appetite, or dehydration occur, notify your prescriber early.

The table below provides a guide to approximate equivalent doses when switching from Mounjaro to Wegovy*

*These are guideline doses (“up to”). Your doctor or pharmacist may adjust your dose based on your previous dose, how well you tolerated Mounjaro, and your overall health. Always follow professional medical advice and do not start or change doses on your own.

Safety and health checks

Neither medicine is suitable for people with certain conditions such as a history of thyroid cancer, pancreatitis, or severe digestive problems.

Different active ingredients

Wegovy contains semaglutide, which works on one hormone (GLP-1) to help control appetite and support weight loss.

Mounjaro works on two hormones (GLP-1 and GIP), which means that you may notice a difference in how full you feel when switching medications.

Weight-loss potential

On average, people using Wegovy lose around 15-17% of their body weight, while Mounjaro users often lose closer to 20–22%.

Although the weight loss may be slightly less than with Mounjaro, Wegovy can be a more affordable option for many people.

It is also important to note that you can lose more than 17% of your starting weight on Wegovy by combining treatment with a calorie reduced diet and exercise.

How quickly they work

Wegovy tends to build up gradually over several weeks.

Mounjaro’s dual action can cause a quicker drop in appetite, sometimes noticeable within the first two to three weeks.

Access and cost

Wegovy is cheaper than Mounjaro and the key driver for most people switching.

It is a good idea to check availability and cost before stopping Mounjaro to ensure a smooth transition.

Dosing difference

Even if you were on a higher dose of Mounjaro, you will need to start Wegovy on a lower dose, allowing your body to adjust.

The dose is then gradually increased every four weeks as tolerated, reducing the chances of side effects.

Timing your switch

You should wait at least one week after having taken Mounjaro, before injecting Wegovy. It is important not to take both medicines at the same time.

Cost

Eli Lilly, the manufacturer of Mounjaro, announced an increase in the price it charges UK providers. As a result, all pharmacies and clinics offering Mounjaro have adjusted their prices.

This change makes Wegovy a more affordable alternative for many people seeking to use weight loss injections.

If you are currently using Mounjaro and are concerned about the price increase, our clinicians can help you review your options. We have streamlined the process of switching from Mounjaro to Wegovy, to ensure a smooth transition with minimal disruption to your treatment.

Improved cardiovascular benefits

Wegovy (semaglutide) has demonstrated proven cardiovascular benefits in clinical studies.

Research has shown that it can significantly reduce the risk of major heart-related events, including heart attack, stroke by up to 20%.

This additional benefit may make Wegovy a more suitable option for people with weight-related heart risks, or those looking to improve overall cardiovascular health alongside weight loss.

Other reasons for changing from Mounjaro to Wegovy

You might also consider switching from Mounjaro to Wegovy for other reasons, such as:

• Availability – One treatment may be easier to obtain than the other due to stock shortages.
• Side effects – Some patients find Wegovy easier to tolerate if they experience nausea or other side effects on Mounjaro.
• Weight loss results – If Mounjaro has not delivered the results you hoped for, Wegovy may offer a better response.
• Prescriber’s recommendation – Your prescriber may advise switching based on your health profile, progress, and treatment goals.

You will not experience withdrawal symptoms when switching from Mounjaro to Wegovy. The recommended 7-day break between treatments aligns with your usual dosing schedule, so you should not notice any significant changes during this time.

Some people may find that their appetite increases slightly during the transition. This happens because the starting dose of Wegovy is often lower than the equivalent Mounjaro dose, giving your body time to adjust safely.

Once you begin Wegovy, you may experience mild side effects, especially when starting or increasing your dose. These effects are usually temporary and tend to settle as your body adapts.

Common Wegovy side effects include:

• Headache
• Nausea (feeling sick)
• Vomiting
• Diarrhoea
• Constipation
• Stomach pain
• Fatigue or weakness

It is possible to experience Wegovy side effects even if you did not have any with Mounjaro, as the two medications contain different active ingredients. Most side effects improve on their own within a few weeks.

There are no specific side effects linked to the switch itself if you follow medical guidance and take the recommended 7-day break. Skipping this gap can increase the risk of nausea, vomiting, or other more serious side effects. Contact your doctor immediately if you start treatment without leaving enough time between doses.