What Is Tirzepatide?
Tirzepatide is a prescription “twincretin” — a single peptide that activates both the GLP-1 and the glucose-dependent insulinotropic polypeptide (GIP) receptors — approved for type 2 diabetes (Mounjaro) and chronic weight management (Zepbound). By engaging two incretin pathways it enhances glucose-dependent insulin secretion, slows gastric emptying, and reduces appetite. It is a prescription drug, not a dietary supplement, and this entry is for reference only. Its efficacy evidence is unusually strong for the encyclopedia — backed by large phase 3 randomised trials.
Evidence
In the phase 3 SURMOUNT-1 randomised, double-blind, placebo-controlled trial of 2,539 adults with obesity, once-weekly subcutaneous tirzepatide produced mean body-weight reductions of roughly 16% (5 mg), 21% (10 mg), and 22.5% (15 mg) over 72 weeks, versus about 2.4% with placebo 1Reference 1RCTTirzepatide Once Weekly for the Treatment of Obesity — randomised controlled trial (SURMOUNT-1)View study →. Its incretin (GLP-1 + GIP) mechanism — improving glycaemic control and reducing appetite — is well established in the diabetes and obesity literature; the parallel SURPASS (diabetes) programme and other SURMOUNT trials were not individually retrieved and verified in this quick pass and should be added in a full pass. The most common adverse effects reported in trials are gastrointestinal (nausea, diarrhoea, vomiting, constipation).
Dosage & Safety
Tirzepatide is a prescription medicine dosed and titrated by a clinician (escalated toward 5–15 mg once weekly by subcutaneous injection in the obesity trials 1Reference 1RCTTirzepatide Once Weekly for the Treatment of Obesity — randomised controlled trial (SURMOUNT-1)View study →); the figures here are informational, not a recommendation, and it must not be self-sourced or self-dosed. It carries a boxed warning regarding thyroid C-cell tumours observed in rodents and is contraindicated in people with a personal or family history of medullary thyroid carcinoma or MEN 2; pancreatitis, gallbladder events, and hypoglycaemia (especially with insulin/sulfonylureas) have also been reported. Because it is a prescription drug and not an approved dietary supplement, full contraindication, interaction, and pregnancy details are outside the scope of this stub and should be confirmed against the official label in a full pass. Informational only.
References
- Jastreboff AM, et al. (2022). Tirzepatide Once Weekly for the Treatment of Obesity — randomised controlled trial (SURMOUNT-1). N Engl J Med, 387:205–216. https://pubmed.ncbi.nlm.nih.gov/35658024/