Legal status, what it is, and the listed suppliers in the United Kingdom that list it.
Legal status in the United Kingdom
Approved medicine. Mounjaro (tirzepatide) holds a Great Britain marketing authorisation, PLGB 14895/0343, listed on the MHRA products register (checked 2026-09-22).
As understood at 2026-09-26. Verify with the MHRA.
What Tirzepatide is
Tirzepatide is a synthetic peptide that activates two hormone receptors at once: GIP and GLP-1, both involved in insulin release and appetite. It is a licensed medicine in the UK, the US and Australia, which makes it the most heavily regulated substance covered on this site, and it has the largest trial programme of anything here.
Jastreboff AM, Aronne LJ, Ahmad NN, et al. (2022). New England Journal of Medicine. human 2,539 adults with obesity, or overweight with a weight-related complication, excluding diabetes; phase 3, double-blind, placebo-controlled, 72 weeks
Jastreboff AM, le Roux CW, Stefanski A, et al. (2025). New England Journal of Medicine. human 1,032 SURMOUNT-1 participants who had both obesity and prediabetes, followed to 176 weeks plus a 17-week period off treatment
Malhotra A, Grunstein RR, Fietze I, et al. (2024). New England Journal of Medicine. human adults with moderate-to-severe obstructive sleep apnoea and obesity across two phase 3 trials, one in people not using positive airway pressure and one in people already using it; 52 weeks
Packer M, Zile MR, Kramer CM, et al. (2025). New England Journal of Medicine. human 731 patients with heart failure, an ejection fraction of at least 50 percent and obesity; international, double-blind, placebo-controlled, at least 52 weeks
Lin CL, Lin KC, Yu JM, et al. (2026). Nature Communications. human humans, 14,118 matched pairs, retrospective cohort from an international federated electronic health-record network, adults with atrial fibrillation and type 2 diabetes