Last clinically reviewed: 9 June 2026 Published 14 May 2025

What are the most common side effects of Mounjaro vs. Wegovy?

James Reynolds
Written by James Reynolds MPharm, DipClinPh, PgCert Derm, SCOPE, IP

Key takeaways

  • 1️⃣ Mounjaro and Wegovy are injectable weight loss medications used in the UK.
  • 2️⃣ Both belong to the GLP-1 receptor agonist class but have distinct side effect profiles.
  • 3️⃣ Gastrointestinal symptoms are common with both, but the severity and types can differ.
  • 4️⃣ Mounjaro may cause increased burping and flatulence, while Wegovy has additional risks like thyroid tumors.
  • 5️⃣ Consulting a healthcare professional is essential when deciding which medication is right for you.

Understanding Mounjaro and Wegovy: what you need to know

When considering weight loss treatments, especially those involving injectable medications, it’s essential to understand how they work and their potential side effects. Mounjaro (tirzepatide) and Wegovy (semaglutide) are two popular options offered at weight loss clinics across the UK. Both are GLP-1 receptor agonists that help manage weight by regulating appetite and glucose metabolism. However, they differ in their formulation and, crucially, their side effect profiles.

At Lotus Weight Loss Clinic, we offer both Mounjaro and Wegovy as part of our weight management programs. Deciding which medication is right for you involves understanding both the benefits and potential risks.

Side effects: breaking down the differences between Mounjaro and Wegovy

 

Both Mounjaro and Wegovy share common side effects due to their mechanism of action on GLP-1 receptors. However, the frequency and intensity of these symptoms can vary.

Common Side Effects of Mounjaro

Mounjaro users frequently experience gastrointestinal issues, including:

*Nausea

*Diarrhea

*Decreased appetite

*Vomiting

*Constipation

*Indigestion

*Abdominal pain

*Burping and flatulence (less common)

These side effects are typically mild and tend to subside as the body adjusts to the medication. Adjusting meal sizes and focusing on hydration can help mitigate these symptoms.

Common Side Effects of Wegovy

Wegovy shares some side effects with Mounjaro but also includes:

 

These symptoms usually decrease over time, especially when dosage is increased gradually. Maintaining a balanced diet and staying hydrated are key to managing these effects.

Serious Side Effects of Mounjaro

  • Pancreatitis: Severe abdominal pain, possibly radiating to the back.
  • Gallbladder Problems: Pain in the upper abdomen, jaundice, or clay-colored stools.
  • Hypoglycemia: Particularly in combination with insulin.
  • Kidney Problems: Dehydration can lead to kidney issues.
  • Severe Allergic Reactions: Swelling, rash, or breathing difficulties.
  • Vision Changes: Often associated with diabetes patients.

Serious Side Effects of Wegovy

  • Pancreatitis: Similar to Mounjaro, with intense abdominal pain.
  • Gallbladder Disease: Can include gallstones requiring surgery.
  • Thyroid Tumors: A boxed warning exists for the risk of medullary thyroid carcinoma.
  • Mental Health Changes: Rare but may include depression or suicidal thoughts.
  • Increased Heart Rate: Tachycardia reported in some cases.
  • Hypoglycemia and Kidney Problems: Similar to Mounjaro, often linked to gastrointestinal symptoms.

Managing side effects: practical tips for users

If you're considering Mounjaro or Wegovy, it’s essential to prepare for potential side effects. Here are some practical tips:

  1. Start Slowly: Begin with the lowest possible dose to minimize gastrointestinal issues.
  2. Stay Hydrated: Dehydration can worsen side effects like nausea and constipation.
  3. Monitor Your Diet: Opt for small, frequent meals to reduce nausea and indigestion.
  4. Be Aware of Warning Signs: If you experience severe abdominal pain or mood changes, seek medical advice immediately.
  5. Regular Monitoring: Stay in touch with your healthcare provider to track any adverse effects.

For more information on our weight loss programs and guidance on medication usage, visit Thinking of Starting?

Conclusion

Both Mounjaro and Wegovy offer promising results for weight loss, but understanding their side effect profiles is essential. Mounjaro may be better tolerated by some due to its milder gastrointestinal side effects, while Wegovy’s potential risks require careful consideration. Always consult with a healthcare professional before starting or switching medications.

Explore our Medications and Pricing page to learn more about your options.

Frequently Asked Questions

How we wrote this article

This article was created in line with our editorial standards. Medical information is checked against UK-relevant guidance and reliable sources, which may include the NHS, NICE, the MHRA, medicine safety information, recognised clinical guidance and peer-reviewed research.

Medical content is reviewed regularly and updated sooner if clinical, safety or regulation guidance changes. This article is general information, and not a substitute for personal advice from your own prescriber.

Something wrong or outdated? Email: support@lotusweightloss.co.uk
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James Reynolds
James Reynolds Lead Clinical Pharmacist MPharm, DipClinPh, PgCert Derm, SCOPE, IP

James Reynolds MPharm, DipClinPh, PgCert Derm, IP is the Lead Clinical Pharmacist at Lotus Weight Loss. With over 15 years of experience in NHS and private healthcare, James specialises in prescribing GLP-1 medications and delivering safe, patient-centred weight management support.

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