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.

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

We’re relaunching our Wegovy weight-loss programme soon. To join our waiting list, click here.

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:

Medication	Average Weight Loss (Clinical Trials)	Second Nature Programme Results	% Achieving >15% Weight Loss
Mounjaro (tirzepatide)	25% after one year (SURMOUNT)	Not yet published	84% (clinical trial data)
Wegovy (semaglutide)	15-17% after one year (STEP)	19.1% after one year	70% (Second Nature data)

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.

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

The recommended dose transition follows this clinical protocol:

Current Mounjaro Dose	Starting Wegovy Dose
2.5mg	0.25mg
5mg	0.25mg
7.5mg	0.5mg
10mg	0.5mg
12.5mg	1mg
15mg	1mg

These transitions are designed to ensure safety while maintaining effectiveness. Most patients will then follow Wegovy’s standard dose escalation schedule:

• 0.25mg for 4 weeks
• 0.5mg for 4 weeks
• 1mg for 4 weeks
• 1.7mg for 4 weeks
• 2.4mg maintenance dose

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)
• Monthly costs for Wegovy typically range from £175-£25, depending on the provider

NHS patients

If you receive Mounjaro through NHS specialist weight management services:

• Switching to Wegovy requires NHS clinician approval
• The NHS has specific criteria for GLP-1 medications
• Availability varies significantly by region

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

Can you switch from Mounjaro to semaglutide (Wegovy)?

Yes, you can safely switch from Mounjaro (tirzepatide) to Wegovy (semaglutide) under medical supervision.

The transition requires following a specific dose conversion protocol designed by healthcare professionals.

The clinical team will determine the appropriate starting dose of Wegovy based on your current Mounjaro dose, typically starting at a lower dose than you might expect to ensure a smooth transition.

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.

How long does it take to adjust to Wegovy after Mounjaro?

Most patients report adjusting to Wegovy within 2-4 weeks after starting. The full transition to your maintenance dose typically takes 4-5 months following the standard dose escalation schedule.

During this time, you may notice changes in appetite, side effects, and energy levels as your body adapts.

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.

How much does Wegovy cost compared to Mounjaro?

Following Eli Lilly’s price increase, Wegovy is now significantly more affordable than Mounjaro for private patients. Typical monthly costs:

• Wegovy: £175-£250 depending on provider
• Mounjaro: estimated cost of £330+ for the highest doses after September 2025 (prices will vary depending on the provider)

NHS patients typically pay only the standard prescription charge (£9.90 in England) for either medication if they meet eligibility criteria.

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.

Join our Wegovy programme waiting list to be notified as soon as it launches. We’re committed to supporting your health journey, regardless of which medication best fits your needs.