Tirzepatide (Mounjaro®) vs Semaglutide (Wegovy®)

What’s the Difference?

Both tirzepatide (Mounjaro®) and semaglutide (Wegovy®) are once-weekly injectable medications used in the management of overweight and obesity.

They work by targeting gut hormones involved in appetite regulation and metabolic control, but there are important differences.

Mechanism of Action

Semaglutide (Wegovy®)

GLP-1 receptor agonist
Mimics the GLP-1 hormone
Reduces appetite
Increases satiety
Slows gastric emptying

Tirzepatide (Mounjaro®)

Dual GIP and GLP-1 receptor agonist
Activates both GIP and GLP-1 pathways
Influences appetite regulation
May have additional metabolic effects

Tirzepatide acts on two hormone receptors, whereas semaglutide acts on one.

Weight Loss Outcomes

Clinical trials have demonstrated meaningful weight reduction with both medications when combined with lifestyle modification. Average weight loss outcomes vary between individuals and depend on:

Baseline BMI
Dose achieved
Tolerability
Lifestyle factors
Individual metabolic response

Tirzepatide has demonstrated higher average weight reduction in clinical trials; however, suitability depends on individual clinical assessment rather than average outcomes alone.

Dosing Structure

Both medications are administered once weekly via subcutaneous injection.

Semaglutide escalation:

0.25 mg → 0.5 mg → 1 mg → 1.7 mg → 2.4 mg

Tirzepatide escalation:

2.5 mg → 5 mg → 7.5 mg → 10 mg → 12.5 mg → 15 mg

Dose increases occur at minimum 4-week intervals and only where clinically appropriate.

Side Effect Profile

Both medications commonly cause gastrointestinal side effects during dose escalation, including:

Nausea
Diarrhoea
Constipation
Reduced appetite
Indigestion

Tolerability varies between individuals. Dose progression depends on response and side effect profile.

Which Is Right for You?

There is no universal “better” medication. The choice between tirzepatide and semaglutide depends on:

Clinical history
Comorbidities
Medication tolerance
Previous treatment response
Individual preference
Cost considerations

Final selection is made following structured clinical assessment.

Medication is prescribed only where appropriate and safe.

Regulatory & Monitoring Standards

Both medications:

Require eligibility assessment
Require GP liaison
Require ongoing 3–4 weekly review
May be paused or discontinued if risks outweigh benefits

Prescribing decisions are based on clinical judgement, not marketing claims.