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Zepbound is the United States brand name for tirzepatide and holds no EU marketing authorisation — the European Medicines Agency has no assessment report under this name. In the European Union the same active substance is sold as Mounjaro.

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What is Zepbound?

Tirzepatide is given as a once-weekly injection under the skin. It acts on two natural gut-hormone signals at once, GLP-1 and GIP, which together lower appetite and slow how fast food leaves the stomach, so people usually eat less. In the United States, Zepbound is labelled by Eli Lilly and Company for weight reduction and for moderate to severe obstructive sleep apnoea in adults with obesity.
Form: pre-filled injection pen. Frequency: once a week. Status: prescription only.
Zepbound has no EU marketing authorisation for this use. No doctor in the EU can prescribe it for this use — including ours. It may be authorised in another country, or for a different condition.

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Not marketed in the EU

In the EU, the same active substance is sold as Mounjaro. Tirzepatide was first authorised in September 2022 for type 2 diabetes, and its licence was extended on 11 December 2023 to cover weight management alongside a reduced-calorie diet and more physical activity.

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How it works

Tirzepatide is a dual GIP and GLP-1 receptor agonist — a single molecule engineered to activate both the GIP receptor (a target not engaged by semaglutide or liraglutide) and the GLP-1 receptor. GIP (glucose-dependent insulinotropic polypeptide) is an incretin hormone that, like GLP-1, is released from the gut after eating. While GLP-1 acts primarily on the hypothalamic arcuate nucleus and brainstem to suppress appetite, GIP is thought to modulate energy storage and utilisation in adipose tissue, and may enhance the weight-suppressing effect of GLP-1 agonism through complementary central and peripheral pathways. In the arcuate nucleus, GIP receptors are co-expressed on a subset of the same neurons that carry GLP-1 receptors, so dual activation amplifies the anorectic signal. The combination also slows gastric emptying and stimulates glucose-dependent insulin release from pancreatic beta-cells.

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What the studies reported

SURMOUNT-1 (N Engl J Med 2022;387:205-216, DOI 10.1056/NEJMoa2206038, ClinicalTrials.gov NCT04184622) was a phase 3, randomised, double-blind, placebo-controlled trial at 119 sites in 9 countries. A total of 2,539 adults with a BMI of 30 or more (or 27 or more with at least one weight-related complication), excluding type 2 diabetes, were assigned in a 1:1:1:1 ratio to once-weekly tirzepatide 5 mg, 10 mg, or 15 mg, or placebo, for 72 weeks including a 20-week dose-escalation period, plus lifestyle counselling in all groups. The coprimary end points were the percentage change in body weight and the proportion of participants losing 5% or more of baseline weight. The treatment-regimen estimand assessed effects regardless of treatment discontinuation in the intention-to-treat population — meaning participants who stopped treatment remained in the analysis. Overall, 86.0% of participants completed the primary treatment period (77.0% in the placebo group, 88.4–89.8% across the tirzepatide groups). The trial did not follow weight after treatment stopped, so it provides no controlled data on longer-term maintenance when tirzepatide is discontinued. Every NCT identifier links to its ClinicalTrials.gov record; a readout is not the same as peer-reviewed publication.
  • ClinicalTrials.gov · NCT04184622 (SURMOUNT-1)

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What has been reported

Acute pancreatitis was independently confirmed in 3 people on tirzepatide and 1 on placebo across the SURMOUNT-1 safety dataset reviewed by the EMA.

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What SURMOUNT-1 did not measure

SURMOUNT-1 did not follow weight after treatment stopped, so it provides no data on what happens when tirzepatide is discontinued. People with type 2 diabetes were excluded from the trial, meaning the side-effect profile in that group is drawn from a different dataset. All participants also received diet and exercise counselling, so the figures reflect the medicine alongside lifestyle support, not the medicine alone.

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Common questions

No. Zepbound has no EU marketing authorisation, so no doctor in the EU can prescribe it for this use. The same active substance, tirzepatide, is sold in the EU under the brand name Mounjaro, which was first authorised for type 2 diabetes in September 2022 and extended to weight management on 11 December 2023.
Zepbound and Mounjaro contain exactly the same active substance — tirzepatide — at the same doses. Zepbound is the US brand name; Mounjaro is the EU brand name. The dosing schedule, side-effect profile and clinical trial data (SURMOUNT-1) are the same.
SURMOUNT-1 did not follow weight after treatment stopped. As with other GLP-1-based medicines, appetite and stomach emptying return to normal once the medicine leaves the body, and weight that was lost may be regained.
No. Tirzepatide acts on two receptors (GIP and GLP-1), while semaglutide acts only on GLP-1. Both are once-weekly injections, but they are different molecules with different trial programmes and different authorised doses.
In SURMOUNT-1, alopecia was reported by 5.1% (5 mg), 4.9% (10 mg) and 5.7% (15 mg) of participants versus 0.9% on placebo. The mechanism is not fully understood, but it is listed in the trial safety data.

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A step-wise, supervised escalation (as used for tirzepatide in the EU)

1

Weeks 1–4

2.5 mg starting dose, once weekly.
2

From week 5

Step up every 4 weeks as tolerated: 5 → 7.5 → 10 → 12.5 mg.
3

Month 4+

Personalised maintenance dose, up to a maximum of 15 mg per week.
4

Ongoing

Quarterly medical reviews.
Once-weekly self-injection is given in the thigh, abdomen or upper arm, and is combined with diet and physical activity — tirzepatide complements, not replaces, lifestyle change.

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Who it is not suitable for

  • Personal or family history of medullary thyroid carcinoma or MEN 2
  • Pregnancy, planned pregnancy in the next 2 months, or breastfeeding
  • History of pancreatitis
  • Type 1 diabetes or diabetic ketoacidosis
  • Severe gastroparesis
You pay for any medication separately at the pharmacy you choose. Hi-Doctor does not sell medications.

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How Hi-Doctor handles it

Weight-loss treatment runs as an ongoing plan: first consultation included, then renewals reviewed by your doctor as part of ongoing care. See the weight management programme for how the categories work, and pricing for how the plan is billed. Related: Qsymia, another US weight-loss medicine without EU-wide authorisation. For the EU-authorised version of tirzepatide, see Mounjaro. For other weight-management options, see semaglutide (Wegovy) and the full treatment areas Hi-Doctor covers.

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Start a consultation

Weight-loss consultation

Answer the weight-loss questionnaire and a registered doctor reviews it. They decide whether treatment is appropriate, which one, and at what dose — and declining is a normal outcome. See what it costs and how the review works.
This page is reference information, not medical advice and not a prescription. Whether a medicine is appropriate for you is decided by a registered doctor after reviewing your consultation.