Switching from Mounjaro to Wegovy pill: A guide

To make sure it’s effective, the Wegovy tablet must be taken:

• on an empty stomach, which means after at least 8 hours of fasting – most people take it in the morning as soon as they wake up
• with no more than 120ml of plain water – no coffee, tea, juice, or any other liquids must be used
• whole, as it cannot be crushed, dissolved, or broken in any way, as this may affect the absorption and effectiveness
• at least 30 minutes before any other drinks, foods, or oral medications

In most cases, you'll start Wegovy tablets when your next Mounjaro injection would normally have been due. This means waiting 1 week after your last Mounjaro injection before starting Wegovy tablets.

The waiting period helps reduce the risk of overlapping treatment and may lower the chance of side effects during the switch. You should only switch between weight loss medications with the help of your doctor.

Mounjaro to Wegovy pill dose conversion

There is no exact dose equivalent between Mounjaro and Wegovy tablets because they contain different active ingredients. Mounjaro contains tirzepatide, which works on both GLP-1 and GIP receptors, while Wegovy tablets contain semaglutide, which only works on GLP-1 receptors.

However, the following guide is commonly used when switching:

Most people currently taking Mounjaro can switch to Wegovy tablets. While you usually need a certain body mass index (BMI) to start weight loss treatment, this is not always necessary when switching treatments. Wegovy tablets may be suitable if you:

• are tolerating GLP-1 treatment well but would prefer a tablet rather than injections
• want to move on to weight maintenance (maintaining your weight with weight loss treatment) and would prefer tablets for the long-term
• and your doctor believes the switch is appropriate

Although both treatments help regulate appetite, switching from Mounjaro to Wegovy tablets is different because you’re switching between 2 different active ingredients. Because tirzepatide and semaglutide work slightly differently, you may notice some temporary changes while your body adapts. This is because it will take a few weeks for semaglutide to build up in your system, while at the same time, tirzepatide will slowly leave your body.

Changes in appetite and fullness

During the first few weeks after switching, you might notice:

• increased hunger between meals
• slightly stronger cravings
• feeling less full after eating
• more awareness of food (‘food noise’)

However, these changes are usually temporary and often improve as semaglutide levels build up in your body. It can take a few weeks, or for you to reach the maximum dose of 25mg if you have not started on this when you switched.

Weight loss progress

Many people continue to lose weight successfully after switching. However, because of the change in treatment, you may experience temporary changes, like:

• a short weight loss plateau
• slower weight loss initially
• a period of adjustment while switching medications

It’s important to try and continue your diet and exercise changes as before, even if for a shorter time it’s more difficult due to increased hunger.

Side effects

The most common side effects after switching are similar to those experienced with other GLP-1 medications.

These can include:

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

Most side effects improve over time as your body adjusts to Wegovy tablet treatment. Even if you did not get side effects on Mounjaro, it’s possible to get them with the Wegovy pill because it’s a new active ingredient, so your body may respond differently. You may also switch with little to no side effects, especially if switching from a high dose to the maximum dose of 25mg as your body has adjusted to high levels of tirzepatide in your body.

Can I switch back to injections if the pill doesn't work for me?

Yes. You can switch back to injections if the Wegovy tablet does not work for you. However, it’s recommended to wait at least a few weeks to give Wegovy tablets time to work in your system and build up the levels of semaglutide to a steady level, or to reach the maximum 25mg dose if you have not already. But if you’re getting unmanageable side effects from taking an oral tablet, speak to your doctor straight away, as switching sooner may be recommended.

When switching from the Wegovy tablet to Mounjaro injections, you will never start back on the highest dose. This is because injected forms of GLP-1 are absorbed much easier into the bloodstream, so starting back at a high dose after taking tablets could cause severe side effects and be unsafe. The general doses recommended to switch to are:

Switching back and forth can slow down your weight loss progress, so if you can, give Wegovy tablets some time to work, as you may find that you get similar results.

Will switching weight loss medications affect my weight loss progress?

Switching weight loss medications is not likely to affect your long-term weight loss progress. While Mounjaro works on 2 hormone pathways and Wegovy works on 1, they still work in a very similar way and cause very similar effects. Even at the highest doses, there is not a huge difference in average effectiveness: 22.5% for Mounjaro after 72 weeks vs up to 17% for Wegovy tablets after 64 weeks. It’s also important to bear in mind that Mounjaro was studied for an extra 8 weeks.

Switching between 2 active ingredients can cause some temporary changes, like an increase in appetite or a plateau in weight loss, but this should settle as Wegovy tablets build up in your system. As long as you keep following the same diet and exercise changes, it’s not likely to cause big changes. However, if you’re finding that Wegovy tablets are not working as well for you after a month or longer on the highest dose, speak to your doctor.

Will I experience more side effects when switching from Mounjaro to the Wegovy pill?

Not necessarily. The side effects for Mounjaro and Wegovy are very similar because both medications affect appetite and digestion. However, some people may get temporary digestive side effects while their body adjusts to the new active ingredient, semaglutide. These should be mild and last a few weeks at most. They are likely to come back if you increase your dose, but if you start at 25mg, this is the maximum Wegovy tablet dosage.

How long do I need to wait after my last injection to start Wegovy tablets?

You need to wait 1 week after your last Mounjaro injection to start Wegovy tablets. This is when your next injection would normally be due, and is to make sure that there is not too much tirzepatide in your system before starting semaglutide.