Tirzepatide: research, uses and evidence

Tirzepatide activates both the GIP and GLP-1 receptors. In SURMOUNT-1, adults with obesity lost an average of 20.9% of body weight at the highest dose over 72 weeks, and in a head-to-head trial it lowered HbA1c and weight more than semaglutide 1 mg.

Structure

39-residue peptide built on the GIP backbone, with a C20 fatty diacid that binds albumin for once-weekly dosing.

How it works

Tirzepatide is an imbalanced dual agonist: it has GIP receptor affinity similar to native GIP and weaker GLP-1 receptor affinity than native GLP-1. The combination enhances insulin secretion, reduces appetite and food intake, and appears to improve insulin sensitivity beyond what weight loss alone explains.

Research use cases

Areas where Tirzepatide has been studied. Inclusion here does not mean it works for that purpose.

Glycaemic control in type 2 diabetes
Chronic weight management
Moderate to severe obstructive sleep apnoea in adults with obesity
Research in heart failure with preserved ejection fraction, MASH and cardiovascular outcomes

What the research found

Weight loss (SURMOUNT-1)

2,539 adults without diabetes were randomized to 5, 10 or 15 mg weekly or placebo for 72 weeks. Mean weight change was −15.0%, −19.5% and −20.9% versus −3.1% with placebo.¹

Head-to-head with semaglutide (SURPASS-2)

In 1,879 people with type 2 diabetes, all three tirzepatide doses were superior to semaglutide 1 mg for HbA1c reduction at 40 weeks, with greater weight loss.²

Obstructive sleep apnoea (SURMOUNT-OSA)

Tirzepatide reduced the apnoea–hypopnoea index by about 25 to 29 events per hour at 52 weeks, versus about 5 with placebo, leading to the 2024 FDA approval for this indication.³

Head-to-head for weight (SURMOUNT-5)

In adults with obesity and no diabetes, tirzepatide produced a mean weight loss of 20.2% at 72 weeks versus 13.7% with semaglutide 2.4 mg.⁴

Safety and open questions

Adverse effects mirror the GLP-1 class: nausea, diarrhoea, vomiting, constipation and decreased appetite, mostly during dose escalation. Labelling carries the same boxed warning for thyroid C-cell tumours, plus warnings for pancreatitis, gallbladder disease and hypoglycaemia with insulin secretagogues. Tirzepatide can reduce the effectiveness of oral contraceptives after starting and after each dose increase because of delayed gastric emptying.

Regulatory status

FDA-approved (Mounjaro, 2022; Zepbound, 2023; Zepbound for obstructive sleep apnoea, 2024). Prescription only.

Status was accurate when this page was last reviewed on October 26, 2026. Regulations change; check with the relevant authority before relying on it.

Tirzepatide: common questions

How is tirzepatide different from semaglutide?

Semaglutide acts on one receptor (GLP-1). Tirzepatide acts on two (GIP and GLP-1). In the SURMOUNT-5 trial, tirzepatide produced more weight loss than semaglutide 2.4 mg over 72 weeks.

Are Mounjaro and Zepbound the same drug?

Yes. Both contain tirzepatide. Mounjaro is labelled for type 2 diabetes; Zepbound is labelled for chronic weight management and obstructive sleep apnoea.

Is Tirzepatide approved for human use?