Is Mounjaro Safe? What We Need To Know

By 
Dr Amit Kumar Singh
 on 
 • 
5
 min read

Mounjaro (tirzepatide) has quickly become a focal point in UK clinics, weight management services, and among patients seeking new options for obesity and type 2 diabetes. But with the excitement comes an essential question: is Mounjaro safe for your patients?

Here’s what we need to know, based on the latest regulatory guidance and clinical evidence.

What is Mounjaro?

Mounjaro (tirzepatide) is a once-weekly injectable medication developed by Eli Lilly. It acts as a dual agonist for GLP-1 and GIP receptors, mimicking hormones that regulate appetite, blood sugar, and insulin. This dual action underpins its effectiveness for both weight loss and glycaemic control in type 2 diabetes.

MHRA and NICE Guidance: Authorised, With Clear Conditions

  • In November 2023, the MHRA authorised Mounjaro for adults with obesity (BMI ≥30 kg/m²) or overweight (BMI ≥27 kg/m²) with at least one weight-related comorbidity, such as hypertension or sleep apnoea. Or from an ethnic background that puts them at higher risk.

  • NICE recommended Mounjaro for NHS use in England and Wales from December 2024, with initial access through specialist weight management services and a phased rollout into primary care from June 2025. With much stricter inclusion criteria outside of the manufacturer's approved licence.

  • Crucially, Mounjaro must be prescribed alongside a reduced-calorie diet and increased physical activity it's not a substitute for lifestyle change.

Clinical Evidence: What Do the Trials Show?

  • SURPASS Trials (Type 2 Diabetes): In the SURPASS-5 trial, patients with type 2 diabetes on insulin saw HbA1c reductions of up to 2.34% and average weight loss exceeding 10 kg over 40 weeks.

  • SURMOUNT Trials (Obesity): The SURMOUNT-1 trial reported 15–21% body weight reductions over 72 weeks in people with obesity but without diabetes. SURMOUNT-4 saw average weight loss above 25%, with most participants maintaining their results.

  • These outcomes underpin the MHRA and NICE approvals, confirming significant benefits for appropriate patients.

Safety Profile and Side Effects

  • Common Side Effects: Gastrointestinal symptoms nausea, diarrhoea, vomiting, and constipation are the most frequently reported. These are generally mild to moderate, often peaking during dose escalation and improving over time.

  • Serious Risks: Rare cases of pancreatitis and gallbladder disease have been observed, likely related to rapid weight loss. Dehydration from GI side effects has also been reported, occasionally requiring hospitalisation.

  • Monitoring: As a "Black Triangle" medicine, Mounjaro is subject to additional safety monitoring. All suspected adverse reactions should be reported via the MHRA Yellow Card scheme.

  • Contraindications: Mounjaro shouldn’t be used in people with a personal or family history of medullary thyroid carcinoma, or those with multiple endocrine neoplasia type 2 — both are clear red flags. It’s also not suitable for anyone with severe gastrointestinal disease or a history of pancreatitis, as these conditions can be worsened by the drug’s effects. 

Prescribing and Patient Selection

  • Eligibility: Mounjaro was initially rolled out through specialist NHS weight management services, with plans for a gradual expansion into primary care for adults at high risk of weight-related complications especially those with obesity-linked conditions like type 2 diabetes or sleep apnoea. That said, it’s also now available privately, either through high-street pharmacies or online clinics like SheMed, for patients who meet the clinical criteria but prefer faster access or personalised support. As always, eligibility depends on more than just BMI  a full health assessment helps determine if it’s the right fit.

  • Wraparound Care: Prescribing must be accompanied by ongoing nutritional, behavioural, and medical support mandated by NHS England and MHRA.

  • Special Considerations: Not recommended during pregnancy, breastfeeding, or for those planning pregnancy. Additional contraception may be needed for women using oral contraceptives, as absorption can be affected.

Bottom Line: Is Mounjaro Safe?

For most patients who meet the eligibility criteria and receive appropriate monitoring and support, Mounjaro is considered safe and effective for weight management and type 2 diabetes. Its safety and efficacy have been demonstrated in large-scale clinical trials.

However, it is not a standalone solution. Success depends on patient engagement with lifestyle interventions and regular clinical monitoring. You should remain vigilant for adverse effects and contraindications, ensuring that prescribing decisions are made on a case-by-case basis with full patient assessment.

At SheMed, patient safety is paramount. That’s why we require a blood test l before starting treatment, to ensure it’s safe and suitable for each individual. If you have any questions or concerns, don’t hesitate to reach out to the SheMed support team we’re here to help. 

References

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