How to switch from Mounjaro to Wegovy safely

Jump to: What to expect when switching | Weight loss comparison | How to switch safely | NHS vs private considerations | Managing side effects | Frequently asked questions | Take home message

You can switch from Mounjaro (tirzepatide) to Wegovy (semaglutide) under medical supervision, with UK clinical protocols recommending specific dose transitions to ensure safety and effectiveness.

When switching, you’ll typically start at a lower dose of Wegovy than you might expect; for example, moving from Mounjaro 10mg to Wegovy 0.5 mg rather than directly to a higher dose.

Starting at a higher dose of Wegovy (rather than the starting dose of 0.25mg) is considered ‘off-label’ use of the medication, but may be recommended by your prescriber if it ensures you maintain your current progress and is considered safe to do so.

Many UK patients are now considering switching medications following the Mounjaro price increase, with affordability being the primary concern.

While Mounjaro may produce slightly greater average weight loss in clinical trials (25% vs 15-17% with Wegovy), Second Nature’s research shows that patients on our Wegovy programme achieve an average of 19.1% weight loss after 12 months, comparable to Mounjaro.

• Switching should always be supervised by healthcare professionals
• Allow 7 days between your last Mounjaro dose and first Wegovy injection
• Expect some adjustment period as your body responds to the different medication
• Maintain consistent healthy habits throughout the transition

Second Nature has launched its Wegovy weight-loss programme, click here to check your eligibility.

What to expect when switching from Mounjaro to Wegovy

The transition between these medications requires careful medical oversight. Most people will need to start at a lower Wegovy dose than might seem equivalent based on their current Mounjaro experience.

During this transition period, you may notice changes in:

Hunger control

Your hunger signals might fluctuate initially as your body adjusts to the new medication mechanism.

Wegovy works primarily through GLP-1 receptors, while Mounjaro targets both GLP-1 and GIP receptors.

“Some patients report a slight increase in hunger during the first 2-3 weeks after switching,” notes Dr. Rachel Hall, Principal Doctor at Second Nature. “This typically stabilises as your body adjusts to the new medication and you reach your maintenance dose.”

Side effect profile

You may experience different side effects as the medications work through slightly different mechanisms:

• Nausea and digestive symptoms may temporarily increase or decrease
• Some patients report less fatigue with Wegovy compared to Mounjaro
• Headaches sometimes occur during the transition, but typically resolve

Weight loss comparison: Mounjaro vs Wegovy

Clinical evidence shows differences in average weight loss outcomes between these medications, though individual results vary significantly:

It’s important to note that Second Nature’s comprehensive approach often produces better results than those seen in clinical trials due to our focus on sustainable habit formation alongside medication.

For someone weighing 100kg, the weight loss difference between medications might be:

• Mounjaro (clinical trials): 25kg average weight loss
• Wegovy (with Second Nature): 19.1kg average weight loss

This 5.9kg difference may be less significant than the potential cost savings and continued support for many patients.

What’s the difference between Mounjaro and Wegovy?

Both medications work by mimicking naturally occurring hormones in our body that regulate hunger and blood sugar.

The doses of these medications vary because of differences in their potency. Wegovy is considered more potent, so effective treatment is achieved with smaller doses (0.25–2.4 mg).

In contrast, Mounjaro is less potent and therefore requires larger doses, starting at 2.5mg and increasing up to 15mg, to effectively help control hunger.

To understand their differences in more detail, let’s briefly look at how each drug works:

How Wegovy works

Wegovy mimics one hormone called GLP-1 (glucagon-like peptide-1), which has three key effects:

• Slows food movement through your stomach, helping you feel fuller longer
• Communicates with your brain’s appetite control centre (the hypothalamus) to reduce hunger
• Improves blood sugar control by improving insulin function

The natural GLP-1 hormone in our body lasts only minutes in the blood before it’s removed from the body, while Wegovy’s effects last for days, providing a longer-lasting effect of lowering hunger and cravings.

Many people report that Wegovy not only reduces physical hunger but also diminishes food cravings and “food noise”, the constant thoughts about food that can lead to overeating.

Many patients find that Wegovy’s focused action on the GLP-1 receptor provides effective hunger control with potentially fewer side effects than dual-action medications.

Mounjaro’s dual-action approach

Mounjaro works on two hormone systems instead of one:

• Like Wegovy, it activates the GLP-1 receptor
• It also activates a second receptor called GIP (glucose-dependent insulinotropic polypeptide)

This dual-action approach is likely why Mounjaro supports more weight loss in clinical trials, as it provides additional blood sugar control and hunger management.

How to switch safely from Mounjaro to Wegovy

Switching from Mounjaro to Wegovy should follow these three stages:

1. Medical assessment

The clinical team will evaluate your:

• Current Mounjaro dose and response
• Overall health status
• Previous side effects
• Weight loss progress

2. Dose transition protocol

What Wegovy dose you’ll transition to will depend on your current Mounjaro dose, side effects, and weight loss progress.

The clinical team will evaluate each individual situation and make a choice that’s best for you. These transitions are designed to ensure safety while maintaining effectiveness.

Each month, you’ll have a monthly check-in with the clinical team to determine your ongoing dose, which can either be decreased, maintained, or increased based on your progress and needs.

3. Transition timing

• Allow 7 days between your last Mounjaro injection and first Wegovy dose
• Schedule a follow-up 2-4 weeks after starting Wegovy
• Expect to reach your maintenance dose within 4-5 months

NHS vs private considerations

When switching between these medications, your options will depend on how you currently access treatment:

Private patients

If you’re currently on a private Mounjaro prescription:

• You can request to switch to Wegovy through your provider if they offer it
• The switch may require a new consultation (some providers charge for this)

NHS patients

If you receive Mounjaro through NHS specialist weight management services:

• You’ll likely continue with your current treatment

NHS eligibility criteria for Wegovy generally includes:

• BMI of 35 or above (or 30+ with weight-related conditions)
• Previous participation in an intensive lifestyle intervention
• No contraindications to GLP-1 medications

Managing side effects during the transition

Some patients experience temporary side effects when switching between GLP-1 medications. Here are practical strategies to manage the most common issues:

Nausea and digestive discomfort

• Eat 3 balanced meals a day based on whole foods and include protein-rich snacks in between meals if you need to
• Choose gentle, easy-to-digest foods during the first few weeks, like scrambled eggs, white fish, and cooked vegetables
• Stay well hydrated between meals (aim for 2 litres daily)
• Consider ginger tea or supplements, which show effectiveness in clinical settings

Fatigue

• Ensure adequate protein intake (at least 25% of each meal)
• Eat iron-rich foods like red meat, liver, and spinach alongside vitamin C (tomatoes, peppers, strawberries)
• Maintain consistent sleep habits

Variations in hunger

• Follow a consistent meal schedule, even if hunger signals vary
• Focus on protein-rich foods at each meal (aim for 30-40g per meal)
• Include plenty of fibre-rich vegetables to maintain fullness
• Plan healthy snacks for times when hunger might increase

Most transition-related side effects should resolve within 2-4 weeks. Maintaining consistent healthy habits during this period is crucial for both managing side effects and continuing your weight loss progress.

Frequently asked questions

Why choose Wegovy over Mounjaro?

The most compelling reasons to choose Wegovy over Mounjaro in 2025 include:

• Cost savings: Following Eli Lilly’s price increase, Wegovy will be significantly more affordable
• Comparable effectiveness: With Second Nature’s support, Wegovy patients achieve 19.1% average weight loss, approaching Mounjaro’s clinical trial results
• Established safety profile: Wegovy has been available longer with more extensive real-world data
• Some patients report fewer side effects: While individual responses vary, some find Wegovy’s side effect profile more manageable
• Wider availability: Wegovy may be more readily available through both private providers and NHS services

When is the wash-out period for Mounjaro before starting Wegovy?

The recommended wash-out period between stopping Mounjaro and starting Wegovy is 7 days. This allows sufficient time for Mounjaro to clear from your system before introducing Wegovy.

This timing helps minimise potential side effects from overlapping medications while maintaining continuous treatment efficacy.

Always follow your healthcare provider’s specific guidance, as they may adjust this timeframe based on your individual health circumstances.

Which has worse side effects, Wegovy or Mounjaro?

Neither medication consistently has “worse” side effects across all patients. Side effect profiles are highly individual:

• Some patients report less nausea with Wegovy than Mounjaro
• Others experience fewer digestive issues with Mounjaro
• Both medications can cause similar side effects (nausea, constipation, diarrhoea, fatigue)
• The intensity of side effects often depends on how quickly doses are escalated

Following the recommended dose transition protocol minimises side effect risk when switching.

Many patients find that side effects stabilise within 2-4 weeks as their body adjusts to the new medication.

Why do some patients feel better taking Wegovy than Mounjaro?

Some patients report feeling better on Wegovy for several reasons:

• Different mechanism: Wegovy targets only GLP-1 receptors, while Mounjaro affects both GLP-1 and GIP, which may cause different responses
• Individual physiology: Everyone responds differently to different medications
• Side effect profile: Some find Wegovy’s side effects more manageable or less intense
• Dosing comfort: Wegovy’s more gradual dose escalation may feel more comfortable for some

Will I regain weight when switching from Mounjaro to Wegovy?

Not necessarily. While Mounjaro shows slightly higher average weight loss in clinical trials, many patients maintain their results when switching to Wegovy, particularly with continued healthy habits.

Second Nature’s data shows our Wegovy patients achieve an average 19.1% weight loss, which is comparable to many Mounjaro results.

Can I switch directly to the highest Wegovy dose?

No. Clinical guidelines specifically recommend starting at a lower Wegovy dose when transitioning from Mounjaro.

This approach reduces side effects and allows your body to adjust to the different medication.

Even if you were on the highest Mounjaro dose (15mg), you would typically start Wegovy at 1mg and then escalate according to the standard schedule.

Take home message

Switching from Mounjaro to Wegovy is a viable option for many patients, particularly following the significant Mounjaro price increase.

While the transition requires medical supervision and patience during the dose escalation period, most patients maintain successful weight management with the proper support and continued healthy habits.

Remember that weight loss medications work best as tools to support lifestyle changes rather than standalone solutions.

The habits you’ve developed during your time on Mounjaro – consistent meal patterns, regular physical activity, stress management, and adequate sleep – remain equally important with Wegovy.

At Second Nature, our approach focuses on these sustainable habits alongside medication, which is why our Wegovy programme produces results that exceed clinical trial outcomes and approach those seen with Mounjaro.

For those concerned about the Mounjaro price increase, Wegovy offers a clinically-proven alternative with comparable real-world effectiveness when combined with comprehensive lifestyle support.

We’re committed to supporting your health journey, regardless of which medication best fits your needs.