How to switch from Mounjaro to Wegovy: What to expect

If you are currently using Mounjaro for weight management, you might be considering your options. Whether this is due to the recent price update or looking for a treatment that suits you better, switching from Mounjaro to Wegovy is a common path many decide to take.

Making the switch requires planning. As the medications contain different active ingredients and work in different ways, you cannot swap one for another without clinician input

Can I Switch from Mounjaro to Wegovy?

Yes, you can switch to Wegovy so long as you meet the safety and eligibility criteria for it, and have the transition approved by a clinician.

Whilst both treatments are injected once-weekly, they contain different active ingredients.

• Mounjaro contains tirzepatide, which activates GIP and GLP-1 hormone receptors.

• Wegovy contains semaglutide, which only activates GLP-1

Because they work differently, a transition must be overseen by a medical prescriber to make sure your weight loss momentum continues safely.

Why Do People Switch from Mounjaro to Wegovy?

Every individual’s weight loss journey is unique but the most common reasons patients choose to switch include:

• Affordability - Following the Mounjaro price increase, Wegovy has now become more cost-effective for many patients accessing treatment privately in the UK.

• Side effects. Some patients experience side effects on a particular treatment but find an improvement when switching to the other.

• Contraceptive convenience. Unlike Mounjaro, Wegovy does not interfere with oral contraceptives, making it more convenient for some women.

• Stalled progress. If weight loss has plateaued on your current treatment, switching to another treatment can sometimes reinvigorate your weight loss journey.

Is It Worth Switching from Mounjaro to Wegovy

Whether or not it is worth switching products is a balance of clinical expectations with your personal goals.

Mounjaro (15mg) has demonstrated slightly higher average weight loss compared to Wegovy (2.4mg), but this does not make Wegovy an inferior product.

In addition to weight loss, Wegovy has been approved for cardiovascular risk reduction, making it a unique option for those with a history of heart disease or risk factors.

What Happens If I Switch from Mounjaro to Wegovy?

• Appetite changes - As you’re moving from a medicine that activates 2 receptors, to one that only activates one, you may notice slight appetite changes or how quickly you feel full, especially during the initial transition period.

• Weight loss continuity - many patients successfully maintain their weight, or continue to lose when they switch, as long as they adjust safely to the appropriate maintenance dose.

• Side effects - When changing medication, an adjustment phase is inevitable. Even if you tolerated Mounjaro well, your body needs to get used to Wegovy.

How the Switch Works: Dosing and Timing

The priority when switching is safety. To prevent severe side effects or the medication levels from overlapping, a structured clinical protocol helps to safely switch over.

One-Week Washout

You cannot use Mounjaro and Wegovy at the same time. Most prescribers will advise a 7-day washout period, between your last Mounjaro dose and the first Wegovy dose.

Essentially, you will miss one week's dose, before moving on to Wegovy.

I.e. If you last injected Mounjaro on a Friday, the next Friday would be a drug-free week. The following Friday you can then safely start Wegovy.

However, if you are actively experiencing side effects from Mounjaro, your clinician may recommend extending this gap until your symptoms settle.

Switching The Dosage

Since the active ingredients in the two treatments are different, there is no equivalence dose.

Regardless of which Mounjaro dose you are on, you will need to start on one of the lower Wegovy doses. This process allows you to assess how your body responds to the new treatment in a relatively safe manner.

To jump straight to a high Wegovy dose can be a bit of a shock to the system, significantly increasing the risk of gastrointestinal side effects.

When Might Staying on Mounjaro Be Better?

Whilst switching to Wegovy is an excellent option for many patients, for some, changing isn’t necessary or ideal. Patients may want to stay on Mounjaro if:

• You are already achieving consistent, steady weight loss with minimal side effects.

• You are on a lower, affordable maintenance dose, where price differences aren’t so big.

• Your clinical history suggests you would respond better to the dual action mechanism.

Next Steps: How to Transition Safely

If you decide switching to Wegovy is the right move for you, start your journey today by completing an online consultation.

As a GPhC-registered pharmacy, our clinical team is here to help you through a smooth transition. We will review your current dose, evaluate your treatment history and side-effect profile to create a personalised treatment plan going forward.