Tirzepatide
Also known as Mounjaro, Zepbound
Tirzepatide activates two receptors, GIP and GLP-1, where semaglutide targets one. It is a licensed medicine in the UK, sold as Mounjaro, and is prescription-only. It has been through the full clinical trial process, which places it in a completely different evidential category from the research compounds elsewhere on this site.
Where to get it
Prescription-only medicine
Tirzepatide is a licensed prescription-only medicine in the UK. The legal route is a prescriber and a registered pharmacy, so we do not list research suppliers for it.
What it has been studied for
- The SURPASS randomised trial programme in type 2 diabetes
- The SURMOUNT trials in weight management
- Head-to-head comparison against semaglutide
- Cardiovascular and long-term safety follow-up
Evidence level: Human trials. Human data exists, but read the details above before assuming it applies to you.
What happened in human trials
In SURMOUNT-1 on the top dose, 31% had nausea, 23% diarrhoea and 12% vomiting. 6% stopped because of side effects. It makes the contraceptive pill less reliable after starting and after each dose rise.
UK legal status
Prescription-only medicine. Legal supply requires a prescription through a registered pharmacy, with prescriber oversight.
Handling
The licensed product is supplied ready to use in a manufactured device. It is not a powder and is not reconstituted. Supplied as a licensed pre-filled device, not a vial.
Questions
How does tirzepatide differ from semaglutide?
Tirzepatide acts on two receptors, GIP and GLP-1; semaglutide acts on GLP-1 alone. Head-to-head trials have compared them directly. Both are licensed prescription medicines in the UK.
Is it available without a prescription?
No, and it should not be. It is a prescription-only medicine and requires a prescriber.
Before you buy anything, run the four-question check for red flags that apply to you.