Wegovy or Mounjaro — which is right for you?

What is different about how they work?

Wegovy contains semaglutide, which acts on glucagon-like peptide-1 (GLP-1), a hormone involved in appetite and blood sugar regulation. Mounjaro contains tirzepatide, which acts on GLP-1 and glucose-dependent insulinotropic polypeptide (GIP), another hormone pathway.

Both can reduce hunger and increase fullness. Their injectable formulations are given weekly under the skin, with doses increased gradually according to the prescription and tolerability. Wegovy also has a UK-licensed daily tablet formulation for adult weight management, with separate instructions. A product licence does not guarantee local stock or NHS access. Acting on two pathways does not by itself establish which medicine is best for an individual.

Do they have the same licensed uses?

Both have adult weight-management licences for obesity, or overweight with a weight-related condition, alongside dietary changes and physical activity. Mounjaro also has a type 2 diabetes licence. Wegovy should not be confused with Ozempic, a different semaglutide product licensed for type 2 diabetes.

Age-specific indications and prescribing requirements differ, so younger people need an assessment against the relevant product information rather than advice intended for adults. A UK licence also does not guarantee access through the NHS: eligibility, service arrangements and clinical priorities can differ.

How should benefits be weighed against tolerability?

Clinical studies help inform decisions, but average results cannot predict your response. Comparisons made using different populations, doses or treatment durations can be misleading. A medicine that you can tolerate and use safely may be more appropriate than one chosen only for a study headline.

The discussion should include diabetes control where relevant, other weight-related conditions, eating patterns, previous treatments and what matters to you. Review should consider wellbeing, physical function and nutrition as well as weight. Neither medicine comes with a guaranteed outcome.

What safety issues do they share?

Nausea, vomiting, constipation and diarrhoea can occur with either. Ongoing vomiting or diarrhoea can cause dehydration. Discuss previous pancreatitis, gallbladder problems, severe digestive symptoms, kidney problems and diabetes eye disease. Insulin or certain diabetes tablets may require review because of low blood sugar risk.

Severe persistent abdominal pain, particularly spreading to the back, needs urgent assessment for possible pancreatitis, inflammation of the pancreas. Tell surgical and anaesthetic teams about either medicine before procedures because delayed stomach emptying can affect care.

How do pregnancy plans and contraception affect the choice?

Neither should be used during pregnancy. Stop semaglutide at least two months before trying to conceive; tirzepatide needs at least one month. Make a plan with your clinician, including alternative diabetes care if needed.

With Mounjaro, people using an oral contraceptive should switch to a non-oral method or add a barrier method for four weeks after starting and after every dose increase. This specific precaution does not apply to Wegovy, although vomiting or severe diarrhoea can affect pill reliability with either.

Can you switch or take both?

Do not combine them or switch without a prescriber’s instructions. Their doses are not equivalent. Ask about timing, starting dose, monitoring and what to do if side effects occur. A clear follow-up plan is part of choosing treatment, not an optional extra.