Choosing between weight loss injections can feel overwhelming, especially with new options like Mounjaro and Wegovy making headlines across the UK. At Happy Pharmacy, we understand that making an informed decision about your health requires clear, trustworthy information backed by the latest NHS guidelines and clinical evidence.

As a regulated online pharmacy offering personalised consultations and ongoing support, we're here to guide you through the key differences between these revolutionary weight loss treatments. Whether you're considering Mounjaro or Wegovy, understanding how these medications work, their safety profiles, and expected results will help you make the best choice for your weight loss journey.

Understanding Weight Loss Injections: The Science Behind Success

Both Wegovy and Mounjaro belong to a class of medications that work by mimicking natural hormones in your body that regulate appetite and blood sugar. These weekly weight loss injections have transformed obesity treatment, offering hope to millions struggling with traditional diet and exercise approaches alone.

Semaglutide is the active ingredient in Ozempic and Wegovy. It works as a GLP-1 receptor agonist to treat type 2 diabetes. People also use it to help them lose weight. Tirzepatide is the active ingredient in Mounjaro and Zepbound, which also can treat type 2 diabetes and encourage weight loss. The key difference lies in their mechanisms: The main difference is that tirzepatide mimics two hormones while semaglutide mimics one.

How Mounjaro Works

Mounjaro contains tirzepatide, a dual agonist. As well as being a GLP-1 receptor agonist, it also mimics a second hormone called glucose-dependent insulinotropic peptide (GIP). This dual action provides:

• Enhanced appetite suppression
• Improved blood sugar control
• Slower stomach emptying
• Increased feelings of fullness

How Wegovy Works

Wegovy contains semaglutide, which works as a single GLP-1 receptor agonist. This medication:

• Reduces appetite by affecting brain signals
• Slows gastric emptying
• Helps regulate blood sugar levels
• Promotes sustained weight loss when combined with lifestyle changes

Happy Pharmacy Eligibility Criteria: Who Can Access Treatment?

At Happy Pharmacy, we make accessing weight loss injections straightforward with clear eligibility criteria designed to ensure your safety and treatment success.

General Eligibility Requirements

To qualify for either Mounjaro or Wegovy through Happy Pharmacy's online consultation service, you must:

• Have a BMI of 30 or above, OR
• Have a BMI of 27 or above with at least one weight-related health condition such as:
  • Type 2 diabetes
  • High blood pressure (hypertension)
  • High cholesterol
  • Sleep apnoea
  • Cardiovascular disease

Our Comprehensive Assessment Process

Happy Pharmacy's qualified prescribers will:

• Review your complete medical history
• Assess any current medications
• Evaluate your weight loss goals
• Determine the most suitable treatment option
• Provide ongoing monitoring and support

Who May Not Be Suitable?

For your safety, these treatments may not be appropriate if you have:

• A personal or family history of thyroid cancer
• Multiple Endocrine Neoplasia syndrome
• Pregnancy or breastfeeding
• Severe kidney or liver problems
• A history of pancreatitis

Clinical Trial Results: Comparing Effectiveness

Mounjaro Weight Loss Results

The majority (89% to 91%) of participants receiving 10-mg or 15-mg doses of tirzepatide achieved at least 5% weight loss. More impressive results show:

• A clinical trial over a 72-week period showed that 96% of the participants taking Mounjaro® (on the highest dose) lost 5% or more of their starting body weight.
• Average weight loss of 15-21% in clinical trials
• Patients taking Mounjaro after a lifestyle intervention saw a weight reduction of almost 20%.

Wegovy Weight Loss Results

The 14.9% mean weight loss that we observed in the semaglutide group is substantially greater than the weight loss of 4.0 to 10.9% from baseline with approved antiobesity medications. Key findings include:

• 86% of participants who received semaglutide, as compared with 32% of those who received placebo, lost 5% or more of baseline body weight
• Average weight loss of 15% over 68 weeks
• The results showed that the 10% average weight loss for people using Wegovy was sustained for up to 208 weeks, or four years.

Safety Profiles: Understanding Side Effects

Common Side Effects (Both Medications)

At Happy Pharmacy, patient safety is our priority. Both medications have similar side effect profiles, though individual experiences vary. Common side effects include:

• Nausea (most common initially)
• Diarrhoea
• Vomiting
• Constipation
• Stomach discomfort
• Headache
• Fatigue

These side effects may be temporary, lasting a few days to weeks. Our Happy Pharmacy support team provides guidance on managing these effects during your treatment.

Safety Considerations

Both medications carry a boxed warning for potential thyroid cancer risk based on animal studies. It's not known whether these drugs can cause thyroid cancer in humans. Your Happy Pharmacy consultation will assess your individual risk factors.

Dosing and Administration: Your Treatment Journey

Mounjaro Dosing Schedule

• Starting dose: 2.5mg weekly
• Gradual increases every 4 weeks
• Maximum dose: 15mg weekly
• 6 different dose strengths available

Wegovy Dosing Schedule

• Starting dose: 0.25mg weekly
• 16-week dose escalation period
• Maintenance dose: 2.4mg weekly
• 5 different dose strengths available

Making Your Choice: Key Differences at a Glance

Cost Considerations and Private Options

While some patients may access these treatments through the NHS, many choose private treatment through regulated providers like Happy Pharmacy for immediate access. Happy Pharmacy offers:

• No waiting lists
• Personalised online consultations
• Ongoing support throughout your journey
• Direct delivery to your door

The Happy Pharmacy Difference: Trust and Support

Choosing Happy Pharmacy for your weight loss injection means:

1. Regulated Care: We're a fully regulated online pharmacy meeting all UK safety standards
2. Expert Consultations: Our qualified prescribers assess your individual needs
3. Personalised Support: Ongoing guidance throughout your weight loss journey
4. Convenient Service: Online consultations and home delivery
5. Transparent Pricing: Clear costs with no hidden fees

Your Next Steps with Happy Pharmacy

Starting your weight loss journey with Mounjaro or Wegovy through Happy Pharmacy is straightforward:

1. Complete our comprehensive online consultation
2. Receive expert assessment from our prescribing team
3. Get your medication delivered discretely to your door
4. Access ongoing support and monitoring

Both Mounjaro and Wegovy offer remarkable potential for weight loss when combined with lifestyle changes. The choice between them often comes down to individual factors including:

• Your specific health conditions
• Previous treatment responses
• Cost considerations
• Personal preferences

At Happy Pharmacy, we're committed to helping you make the right choice for your circumstances. Our regulated online service provides the trust, safety, and support you need for successful weight loss.

Frequently Asked Questions

Can I switch between Wegovy and Mounjaro?

Yes, but you'll need medical supervision. You'll also need to wait at least 5 weeks after your last dose of Wegovy before you can start the Mounjaro dosage schedule, and you'll always start at the lowest dose.

Which is more effective for weight loss?

Mounjaro, taken at the maximum dose of 15 milligrams (mg) once per week, was found to cause greater weight loss than Wegovy, taken at the maximum dose of 2.4 mg once per week. However, individual results vary.

How quickly will I see results?

Most patients begin seeing results within 4-8 weeks, with significant weight loss typically occurring over 6-12 months with continued use and lifestyle modifications.

Are these medications safe?

When prescribed and monitored by qualified healthcare professionals like those at Happy Pharmacy, both medications have established safety profiles. Regular monitoring ensures optimal results and safety.

Start Your Weight Loss Journey Today

Don't let confusion about weight loss injections delay your health transformation. Happy Pharmacy's expert team is ready to guide you through a personalised online consultation, helping you choose between Mounjaro and Wegovy based on your unique needs.

Visit Happy Pharmacy online today to begin your consultation. With our regulated service, competitive pricing, and ongoing support, you're choosing a trusted partner in your weight loss journey.

Disclaimer

This article is for informational purposes only and does not replace professional medical advice. Always consult with a qualified healthcare provider before starting any new medication.

Blog medically reviewed by : Harminder Deol, GPhC Registered Prescriber, 2 July 2025