Metabolic
Tirzepatide
Mounjaro ยท Zepbound
The drug behind Mounjaro, and the most-used GLP-1 among people paying privately in the UK. It works like semaglutide but hits two hormone pathways instead of one, which is generally why the weight loss tends to be larger.
Dual / with large phase 3 weight-management trials and current UK authorisation.
How well studied
Tier Guide: A = Well studied, B = Some good studies, C = Early evidence & D = Barely studied
Backed by large human trials, so we have solid data on how it works and what it does.
UK status
How you could legitimately come across it here, if at all
The MHRA has assessed this and authorised it as a UK medicine, so it can be prescribed and dispensed through the normal system.
Evidence strength and UK regulatory status answer different questions.
Overview
How it works
Copies two different gut hormones at once instead of one, which is why appetite tends to drop more than it does with single-pathway drugs.
Activates two gut pathways ( and ) simultaneously for stronger appetite and metabolic effects than single-pathway drugs.
Reported benefits
- Largest weight loss of any licensed UK drug (~20% average in trials)
- Improves blood glucose control
- Improves lipid markers
Who it's typically used for
Timeline to results
Safety & UK access
Dosage
UK Mounjaro SmPC: 2.5 mg subcutaneously once weekly to start, increased to 5 mg after four weeks, then in steps of 2.5 mg after at least four weeks at the current dose. Adult maintenance doses are 5, 10 or 15 mg weekly, with 15 mg weekly the maximum. Prescriber supervised.
Side effects
- Nauseavery common in adults treated for weight management or type 2 diabetes, especially during escalation (UK SmPC)
- Diarrhoeavery common in the same population (UK SmPC)
- Vomitingcommon in the same population (UK SmPC)
- Injection site reactionscommon in the same population (UK SmPC)
Getting it in the UK
The MHRA has assessed this and authorised it as a UK medicine, so it can be prescribed and dispensed through the normal system.
Where it turns up
- NHS, if you meet the criteria
- Private prescription
Checked and authorised for use in the UK. Available on the NHS if you meet the criteria, or privately.
MHRA-licensed: NHS (criteria-based) and private; 4 in 5 UK GLP-1 users are on this drug
MHRA: the UK regulator that assesses whether a medicine is safe and works before it can be authorised for use here. Something not being MHRA-licensed does not automatically mean it is illegal, and it does not mean it is safe.
This is background information about UK regulation, not advice about what you can or should obtain.
Evidence & sources
Why this rating?
The A to D rating shown above comes from our earlier editorial review and is still waiting to be migrated into the structured review record below. That is a gap in our record-keeping, not a sign the rating is wrong.
Evidence fingerprint
No route and indication scope has been published for this profile yet, so no fingerprint is shown.
Sources
Structured source audit not yet published for this profile. The references behind this page are being catalogued one compound at a time, and this one has not been through that process yet.
Content freshness
- Last reviewed
- 24 Sept 2026
- Regulatory status last checked
- 24 Sept 2026