Mounjaro Drug Name and Type: What Tirzepatide Is (October 2026)

01 · The short answer

What is the drug name, and what type of drug is Mounjaro?

The generic drug name is tirzepatide, and Mounjaro is the brand name Eli Lilly sells it under. Every Mounjaro pen contains tirzepatide and nothing else as the active ingredient, so "what drugs are in Mounjaro" has a simple answer: one drug, tirzepatide.¹

As for type, tirzepatide is a once-weekly injectable prescription medicine. Clinically it is called a dual GIP and GLP-1 receptor agonist. In plain terms, it copies two natural gut hormones that help regulate appetite and blood sugar.¹¹¹

If you want the naming covered from other angles, our guides to the Mounjaro name and another name for Mounjaro go through the same ground, and the page on the Mounjaro producer covers Eli Lilly.

02 · What to do next

Is this relevant to you, and what happens next?

It is relevant if you are an adult living with excess weight or type 2 diabetes and are weighing up injectable treatment. Mounjaro is used alongside a reduced-calorie diet and increased physical activity, and it is supplied only after a consultation reviewed by a GPhC-registered prescriber.¹

If you want to see how treatment works in practice, our weight loss clinic page explains the pathway. Ready readers can look at the Mounjaro pen, where the starting 2.5mg pen has a standard price of £169.99 per month (prices checked 10 October 2026). The consultation is free and the price shown is the price paid.

03 · Mounjaro injection uses

Mounjaro injection uses: what it is prescribed for

Mounjaro is the brand name for tirzepatide, a once-weekly injectable prescription medicine made by Eli Lilly. In the UK it is licensed for weight management in adults and for type 2 diabetes.¹

For weight management, the guidance that shapes NHS prescribing is NICE's recommendation on tirzepatide for overweight and obesity.⁴ For type 2 diabetes, there is separate NICE guidance on tirzepatide.⁸ The two uses are assessed differently, so your prescriber will look at your own circumstances and not just the drug.

Treatment works alongside a reduced-calorie diet and increased physical activity, not instead of them. Mounjaro is not a cosmetic quick fix, and individual results vary. For a longer look at the practical side, see our guide to Mounjaro uses.

If you are curious about another use, speak to a prescriber rather than relying on internet claims.

04 · How it works

How tirzepatide works as a drug type

Tirzepatide is the first treatment of its kind to activate two natural gut-hormone receptors at once: GIP and GLP-1.¹ Together these help regulate appetite, slow how quickly the stomach empties, and improve the way the body responds to insulin.

In practice, most people feel fuller sooner and less hungry between meals, which supports a reduced-calorie diet. That is the mechanism behind the question "how does Mounjaro work for weight loss?": it changes appetite signals, and you still do the work of eating less and moving more.¹

This dual action is what distinguishes Mounjaro from single-action GLP-1 medicines such as semaglutide (Wegovy/Ozempic).¹ Single-action means those medicines act on the GLP-1 receptor only. Tirzepatide acts on both.

Tirzepatide has a half-life of about five days, so after a final dose it takes roughly four to five weeks to clear the system. There is no way to speed this up, and nothing needs doing while it clears.¹

05 · Similar drugs compared

Tirzepatide drugs and other GLP-1 medicines

Tirzepatide is one of several injectable weight-management and diabetes medicines, and they are not interchangeable. The table sets out the differences between them.

Wegovy's titration steps up after at least four weeks and reaches the 2.4mg maintenance dose from week 17.¹⁸ Liraglutide is a daily injection, unlike once-weekly Mounjaro and Wegovy. So the generic name for Ozempic is semaglutide, and the generic name for Mounjaro is tirzepatide.

SURMOUNT-5 was the first large head-to-head trial of tirzepatide and semaglutide for weight loss.¹⁵ For a broader overview of the newer options, see what's the new weight loss drug and the name of the diabetes weight loss drug.

Newer tablet medicines also exist, such as Wegovy tablets and Foundayo, but they are separate products with their own prescribing information. Ask your prescriber which option suits you.

06 · Strengths and dosing

Mounjaro strengths and how the dose builds

Mounjaro comes as a pre-filled multi-dose pen (KwikPen) in six strengths: 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg and 15mg.¹ Each KwikPen contains four weekly doses, so one pen lasts four weeks.¹

Everyone starts Mounjaro on 2.5mg once a week. This starting dose is about letting your body adjust, not about weight loss itself. After at least four weeks the dose increases to 5mg, and can then step up by 2.5mg at intervals of no less than every four weeks (7.5mg, 10mg, 12.5mg) up to a maximum of 15mg weekly, depending on how you respond and tolerate it.¹

Many people settle at a maintenance dose of 5mg, 10mg or 15mg. Higher is not automatically better, and your prescriber will guide the right pace.¹

07 · Injecting and storing

How to take Mounjaro and how to store it

Mounjaro is injected under the skin (subcutaneously) once a week, on the same day each week, at any time of day, with or without food.¹ There is no "best" time of day; what matters is the same day each week. Many people choose a weekend morning so early side effects fall on days off.

Licensed injection sites are the stomach area, the front of the thigh, or the back of the upper arm if someone else gives the injection. Rotate the site with each dose.

If you miss a dose, take it as soon as you can within 4 days (96 hours) of the scheduled time, then carry on with your usual day. If more than 4 days have passed, skip the missed dose entirely and take the next one on your normal day. Never take two doses within 3 days of each other. You can change your weekly injection day if needed, as long as at least 3 days (72 hours) have passed since your last dose.

Keep pens in a fridge at 2–8°C and never freeze them. Once in use, a pen can be kept out of the fridge not above 30°C for up to 30 days, after which it should be discarded. Keep the cap on to protect it from light.¹ Unopened pens keep in the fridge until the printed expiry date. If an unopened pen has been out of the fridge, check with the pharmacy before using it.

08 · Results and pace

What results to expect from this type of drug

Weight loss on Mounjaro is gradual by design, and trial averages do not predict your own result. In the SURMOUNT-1 trial of 2,539 adults, people taking tirzepatide alongside diet and exercise lost on average 15% of their body weight on 5mg, 19.5% on 10mg and 20.9% on 15mg over 72 weeks, compared with 3.1% with lifestyle changes alone.²

These are trial averages. Individual results vary, and treatment works alongside a reduced-calorie diet and increased physical activity, not instead of them.²

The first weeks on 2.5mg are an adjustment phase and losses are usually modest. Most measurable progress builds from 5mg onward, month by month. Think in months, not days, and judge progress by trend, not individual weigh-ins.¹ So how much can you lose in a month? It varies, and early loss includes water weight; the trend over weeks matters more than any single result.

Treatment response is reviewed by your prescriber. If you have lost less than 5% of your starting weight after 6 months on the highest dose you can tolerate, your prescriber will discuss whether continuing or stopping is right for you.¹

09 · NHS and private

Is Mounjaro available on the NHS?

Mounjaro is available on the NHS, but access is being phased in over several years. NICE recommends it for adults with a BMI of at least 35 plus at least one weight-related condition, and the NHS primary-care rollout began in June 2025 with the highest-need groups first, initially BMI 40+ with four or more qualifying conditions.⁴⁶

Full rollout is expected to take years, which is why many people who meet the licensed criteria choose regulated private treatment rather than waiting. If you are on the NHS pathway, your GP or weight-management service is the right place to ask where you sit in the phasing. If you go private, look for a GPhC-registered pharmacy; ours is registered under GPhC 9012878. For cost context, see our guide to the Mounjaro drug tariff price.

10 · Safety and look-alikes

Safety: fakes, supplements and "poor man's Ozempic"

Mounjaro is a prescription-only medicine, so be wary of anyone offering to supply it without a consultation or prescription. The MHRA publishes counterfeit medicine alerts, and you can report suspected side effects or fakes through the Yellow Card scheme.⁷¹⁹

The phrase "poor man's Ozempic" is internet shorthand, most often attached to berberine, which is sold as a low-cost supplement with no clinical oversight. Berberine is not tirzepatide, not semaglutide and not a GLP-1 medicine, and it does not share their licensing or trial evidence. Supplement dosing is not standardised, and we make no claim that it matches a prescription medicine.

If you are on an oral contraceptive, note that Mounjaro slows stomach emptying, which can reduce how well the pill is absorbed.⁷ The SmPC advises switching to a non-oral method, or adding a barrier method (such as condoms), for 4 weeks after starting Mounjaro and for 4 weeks after each dose increase.¹ If you take insulin or a sulfonylurea alongside Mounjaro, watch for low blood sugar (shakiness, sweating, confusion); your prescriber may need to adjust those medicines.

Seek immediate medical help for severe, persistent stomach pain that may spread to your back, with or without vomiting (possible pancreatitis); pain in the upper right abdomen, fever or yellowing of skin/eyes (possible gallbladder problems); or signs of a severe allergic reaction such as swelling of the face or throat and difficulty breathing. Tell your prescriber about any new or lasting symptom. You can report suspected side effects through the MHRA Yellow Card scheme.¹³