Tirzepatide vs Mounjaro: What Is the Difference? (October 2026)

01 · The verdict

Tirzepatide vs Mounjaro: the short verdict

Tirzepatide is the medicine and Mounjaro is the brand it is sold under in the UK, so there is nothing to choose between. Mounjaro is a once-weekly injectable prescription medicine made by Eli Lilly. It is licensed in the UK for weight management in adults and for type 2 diabetes.¹ If a product claims to be tirzepatide but is not Mounjaro, it is not the licensed UK pen. That is the point to be careful about.

The comparison that does matter for most readers is between Mounjaro (tirzepatide) and Wegovy (semaglutide 2.4mg), the two licensed weight-management injections. Both are effective, licensed treatments. In the head-to-head SURMOUNT-5 trial, adults on tirzepatide lost 20.2% of body weight on average over 72 weeks, against 13.7% on semaglutide 2.4mg.¹⁵ Which one suits you depends on your health profile, tolerance and prescriber advice, not the headline number alone.

Who each option suits:

• Mounjaro (tirzepatide): adults who want the dual GIP and GLP-1 mechanism and meet the licensed criteria, after review by a prescriber.
• Wegovy (semaglutide 2.4mg): adults for whom a prescriber prefers a single-action GLP-1 medicine, or who are already established on it and doing well.
• Unlicensed or compounded "tirzepatide": nobody. There is no regulated supply chain and no safety data behind these copies.¹

02 · Side by side

Mounjaro, Wegovy and look-alike tirzepatide compared

Trial figures come from separate trials, except SURMOUNT-5, which is the first large head-to-head trial.

03 · Deciding

The factors that actually decide it

First, eligibility. Both licensed medicines need a prescriber to judge whether treatment is appropriate for you. Our free consultation is reviewed by a GPhC-registered prescriber, not a scoring script, and unsuitable orders are refunded automatically.

Second, supply. We supply Mounjaro through official LillyDirect supply, sourced directly from Eli Lilly's UK distribution, as genuine KwikPens, and all six doses are in stock. You can see current prices and start on the Mounjaro pen page.

Third, switching and history. If you already take Wegovy or Ozempic, there is no licensed direct conversion, and a prescriber supervises any change. Fourth, cost over time. A first year costs £2,711.88 at standard prices if you settle at 5mg, up to £3,599.88 at 15mg, before discounts. Across the UK pharmacies we track, Mounjaro pens range from £143.96 to £339.00 depending on dose and provider (checked 10 October 2026). Compare doses on our dose and cost comparison.

04 · Same drug, two names

Is tirzepatide the same as Mounjaro?

Yes: Mounjaro is the brand name for tirzepatide, a once-weekly injectable prescription medicine made by Eli Lilly.¹ The relationship is the same as between any active ingredient and the branded product containing it. Tirzepatide describes the molecule. Mounjaro describes the licensed, quality-controlled pen, the packaging, the patient leaflet and the supply chain that go with it.

In the UK, Mounjaro is licensed for weight management in adults and for type 2 diabetes. It comes as a pre-filled multi-dose pen, the KwikPen, in six strengths: 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg and 15mg.¹ The strength is the dose per weekly injection.

Why the confusion exists

Some pages use "tirzepatide" when they mean the medicine in general, such as trial results or how it works. Others use "Mounjaro" when they mean the product you can buy. Forum threads often use them interchangeably, which is reasonable because they are the same thing, but it leaves newcomers wondering whether a cheaper "plain tirzepatide" exists.

What about "tirzepatide vs tirzepatide"?

If both are licensed UK Mounjaro pens, there is no difference in the active ingredient, only in the strength. If one is a "research peptide", a vial from an online seller or a compounded copy, you are comparing a licensed medicine with something that has no UK licence. Mounjaro must not be combined with unlicensed "research" peptides or compounded copies, because these have no safety data and no regulated supply chain.¹

A useful test: a licensed pen arrives with a patient information leaflet, a printed expiry date and a pharmacy you can look up. You can verify our registration on the GPhC register (number 9012878). A product with no leaflet, no prescriber and no register entry fails that test.

What stays the same, whatever you call it

Treatment is used alongside a reduced-calorie diet and increased physical activity, not instead of them. It is prescription-only and supplied only after an online consultation reviewed by a GPhC-registered prescriber. The leaflet for the pen lists the side effects and instructions, and it is worth reading before your first injection.¹³

You can ask for either "tirzepatide" or "Mounjaro". Prescribers and pharmacists will understand both, and what you receive in the UK on a legitimate prescription will be a Mounjaro KwikPen.

05 · How tirzepatide works

How tirzepatide works, and how it differs from semaglutide

Tirzepatide activates two natural gut-hormone receptors at once, GIP and GLP-1, and it is the first treatment of its kind to do so.¹ Together these actions 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.

This dual action is what distinguishes Mounjaro from single-action GLP-1 medicines such as semaglutide, the ingredient in Wegovy and Ozempic.¹ That difference is why the SURMOUNT-5 head-to-head trial matters.

Why a weekly injection works

Tirzepatide has a half-life of about five days. That is why one injection a week is enough, and it also means that after a final dose it takes roughly 4 to 5 weeks to clear the system.¹ There is no way to speed this up, and nothing needs doing while it clears. If you stop treatment, the effects fade gradually rather than ending on the day of the last injection. Any plan to come off treatment is best made with your prescriber.

What the mechanism means day to day

Slower stomach emptying is the part people notice. Because the stomach empties more slowly, tablets taken by mouth can be absorbed differently. For example, the medicine can reduce absorption of oral contraceptives, which is a reason to discuss contraception with your prescriber and the leaflet before starting.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 sulfonylureas for diabetes, doses may need adjusting because of the risk of low blood sugar. That is a conversation for your prescriber, not a reason to avoid the medicine outright.

Comparing it with other medicines

Semaglutide (Wegovy) is a single-action GLP-1 medicine, and liraglutide (Saxenda) is a daily injection, unlike once-weekly Mounjaro and Wegovy. Newer agents in development have their own mechanisms and are not UK-licensed. If you are curious how they are being discussed against tirzepatide, see our pages on eloralintide in development, maridebart cafraglutide and pemvidutide. None of these is a licensed UK treatment, and we do not supply them.

Medicines used for other conditions are a different matter. Our guide to setmelanotide and tirzepatide explains why a medicine for a specific rare condition is not an alternative to a general weight-management treatment, and our guide to sermorelin does the same for a peptide often marketed alongside these products.

06 · Trial results compared

What the trials show for tirzepatide and semaglutide

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.

At 72 weeks, 85% of participants on 5mg, 89% on 10mg and 91% on 15mg had lost at least 5% of their body weight. Half of participants on 10mg and 57% on 15mg lost at least 20% of their body weight.²

A worked example, not a forecast

To make a percentage concrete: for someone starting at 100 kg, 20.9% is about 21 kg. That is simple arithmetic on a trial average. It is not a prediction for you, and trial averages do not predict your own result.

The first large head-to-head trial: SURMOUNT-5

SURMOUNT-5 is the first large head-to-head trial. Adults on tirzepatide lost on average 20.2% of body weight over 72 weeks versus 13.7% on semaglutide 2.4mg (Wegovy).¹⁵ In the detailed results, 751 adults took one medicine or the other for 72 weeks:

These percentages are the share of participants reaching each threshold.¹⁵ Both are effective, licensed treatments. Which suits you depends on your health profile, tolerance and prescriber advice, not the headline number alone.

What semaglutide achieved in its own trial

In STEP 1, adults on semaglutide 2.4mg (Wegovy) lost on average 14.9% of body weight over 68 weeks, compared with 2.4% on placebo.⁹ There, 86.4% lost at least 5% of body weight (31.5% on placebo), 69.1% lost at least 10% (12.0%) and 50.5% lost at least 15% (4.9%).⁹ STEP 1 and SURMOUNT-1 were different trials with different designs, so their numbers should not be set side by side.

If you are weighing up Mounjaro against other, older options, our guides to Xenical (orlistat) and Duromine set out how those treatments differ in approach.

07 · Cost across a year

Is tirzepatide cheaper than Mounjaro?

No: in the UK the licensed tirzepatide product is Mounjaro, so a legitimate price for tirzepatide is a Mounjaro price. If something sold as "tirzepatide" looks far cheaper, the likely reason is that it is not the licensed pen, and the saving comes with no regulated supply chain behind it.

Across the UK pharmacies we track, Mounjaro pens range from £143.96 to £339.00 per month depending on dose and provider (checked 10 October 2026). For the 2.5mg starting pen, the range is £143.96 to £179.99. For the same dose, the gap between providers runs from £27 to £41. Boots' Mounjaro dose prices run from £179.00 to £339.00.

What it costs with us

Our standard price for one pen (four weeks) is £169.99 at 2.5mg, £218.99 at 5mg, £279.99 at 7.5mg, £290.99 at 10mg, £319.99 at 12.5mg and £329.99 at 15mg. That works out weekly at £42.50, £54.75, £70.00, £72.75, £80.00 and £82.50. A new customer's first order at any dose is £40 off with code FIRST40, including people switching to us at a higher dose. Your first 2.5mg pen therefore costs £129.99, and switching at 15mg means your first order is £289.99. After that, an automatic £25 reorder discount applies to every future order (code DOSE25).

Planning the first year

If you step up after 4 weeks on each dose, your first four pens (2.5mg to 10mg) cost £959.96 at standard prices. A first year of 52 weeks (13 pens) costs £2,711.88 if you settle at 5mg, up to £3,599.88 at 15mg. These totals are before discounts: a new customer's first order is £40 less and every later order £25 less. If you settle at 7.5mg, 10mg or 12.5mg, your monthly price is £279.99, £290.99 or £319.99 respectively.

Comparing with Wegovy

Wegovy's first pen costs £99.99 as a first order; see the Wegovy pen page for current prices.

Payment is by Visa or Mastercard, Klarna or pay-monthly options, with no subscriptions. The consultation is free, and the price shown is the price paid, with no hidden fees. Delivery is free next-day tracked, with Saturday delivery at £14.99. Prices were checked on 10 October 2026.

08 · NHS or private

Getting tirzepatide on the NHS or privately

Mounjaro is available on the NHS, but access is being phased in over several years.⁴ NICE recommends it for adults with a BMI of at least 35 plus at least one weight-related condition. The NHS primary-care rollout began in June 2025 with the highest-need groups first, initially BMI 40+ with four or more qualifying conditions.⁶ Full rollout is expected to take years, which is why many people who meet the licensed criteria choose regulated private treatment rather than waiting.

What NHS prescription charges mean here

In England, NHS prescriptions carry a £9.90 charge per item unless you are exempt. Whether and when you can access Mounjaro through NHS primary care depends on where you sit in the phased rollout. Your GP can tell you where you stand. The NHS guide to tirzepatide explains the NHS position in plain language.⁵

The private route, step by step

Private treatment through a regulated pharmacy follows a defined path, and it is the same medicine either way:

• Free online consultation: a short health questionnaire, with no charge and no obligation.
• Prescriber review: reviewed by a GPhC-registered prescriber. Payment is taken when you place the order; if the prescriber decides the treatment is not suitable, the order is refunded automatically in full.
• Dispensing and dispatch: dispensed by our registered pharmacy, with same-day dispatch when ordered by 3pm.
• Delivery: free next-day tracked delivery by DPD in temperature-controlled, discreet packaging.

You can start your free consultation without commitment.

Aftercare and repeat orders

Ongoing monthly reviews, dose titration and follow-up assessments are carried out by the prescribing team, with side-effect support. Repeat orders re-check suitability, and there is no auto-shipping. Needles, a sharps bin and injection guidance come with every order. Support runs Monday to Friday, 9am to 5pm, by email at support@everydaymeds.co.uk, account portal chat or phone on 0333 207 0413. You can also track your journey with GLPTrackr, our free companion app for iOS and Android.

NHS or private: how to choose

If you meet the NHS criteria and your area has opened access, the NHS route costs nothing beyond any prescription charge. If you do not meet them yet, or do not want to wait, regulated private supply gives you the same licensed medicine after prescriber review. What matters is that it is a genuine pen from a registered pharmacy, not which route you take.

09 · Safety and drawbacks

The drawbacks of tirzepatide and how to use it safely

The honest drawbacks are practical as well as medical: it is a weekly injection, it is a prescription medicine that needs ongoing review, and it works alongside a reduced-calorie diet and increased physical activity, not instead of them.¹ It is also not a treatment you can start from an unregulated seller and trust to match what the trials tested.

Side effects

Like all medicines, Mounjaro can cause side effects, and most are digestive. The most common, affecting more than 1 in 10 people, are nausea, diarrhoea, vomiting, constipation and abdominal discomfort. Side effects are most likely when starting treatment or moving up a dose, and for most people they ease within days to a few weeks as the body adjusts. Read the patient information leaflet before your first dose.¹³ Tell your prescriber about any new or lasting symptom. You can also report suspected side effects through the MHRA Yellow Card scheme.¹⁹

Interactions to raise at consultation

Mounjaro slows stomach emptying, which can reduce how well oral contraceptive pills are absorbed. 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.⁷ If you use insulin or sulfonylureas, doses may need adjusting because of the risk of low blood sugar. Never run two GLP-1 medicines together. Mounjaro must not be combined with other GLP-1 medicines, unlicensed "research" peptides such as retatrutide (which has no UK licence), or compounded copies.¹ If something promises faster results outside a licensed pathway, that is the warning sign.

Counterfeits and look-alike products

The MHRA publishes counterfeit medicine alerts and runs the Yellow Card scheme.⁷ Signs to treat as red flags include a seller offering to supply without a consultation or prescription, dramatic weight-loss claims, and products with no patient information leaflet. A UK pharmacy must be on the GPhC register. Check ours with number 9012878.

Storage and handling

Store unopened pens in the fridge until first use, and they keep until the printed expiry date. Once in use, a KwikPen is licensed for up to 30 days (not above 30°C) out of the fridge.¹³ For anything else, including an unopened pen left out of the fridge, check the patient information leaflet or contact the pharmacy rather than guessing. Follow the pen's instructions for how to inject.

When to speak to a prescriber

Mounjaro must not be used during pregnancy, and it should be stopped at least one month before trying to conceive. If you become pregnant during treatment, stop the medicine and tell your prescriber promptly. Talk to your prescriber before starting if you take diabetes medicines or have any condition you are unsure about. Our monthly reviews exist for exactly this reason. Standard disclaimer: Mounjaro (tirzepatide) is prescription-only, supplied only after an online consultation reviewed by a GPhC-registered prescriber. Individual results vary. This page is information, not a substitute for medical advice.

10 · Alternatives and Ozempic

Ozempic, Wegovy, tablets and other alternatives

Ozempic is semaglutide licensed for type 2 diabetes. It is not a UK weight-loss medicine, and prescribing it privately for weight loss is off-label. The licensed weight-management options are Mounjaro (tirzepatide) and Wegovy (semaglutide 2.4mg).¹⁸ So "Mounjaro vs Ozempic" for weight loss is really Mounjaro vs Wegovy, and a regulated UK pharmacy will not supply Ozempic for weight loss.

How do tirzepatide and semaglutide compare?

The first large head-to-head evidence is SURMOUNT-5, in which tirzepatide averaged 20.2% weight loss against 13.7% on semaglutide 2.4mg over 72 weeks.¹⁵ Both are effective, licensed treatments; individual results vary, and tolerance, your health profile and prescriber advice matter alongside the headline number.

Is there a tablet?

There is no tablet form of Mounjaro, as tirzepatide is injection-only in the UK.¹ Two GLP-1 weight-loss tablets are now licensed in the UK: Wegovy tablets (oral semaglutide, made by Novo Nordisk), approved by the MHRA in June 2026, and Foundayo (orforglipron, made by Eli Lilly), approved in August 2026.²⁰²¹ They are different medicines from Mounjaro, with their own dosing, eligibility checks and trial results, and both are prescription-only. No trial has compared Mounjaro directly with either tablet, so results from separate trials should not be set against each other as if they were head to head. See current Wegovy tablet prices on our weight loss treatments page.

What counts as a cheaper alternative?

Wegovy and Saxenda (liraglutide) are other licensed injectables, and liraglutide is a daily injection supplied at 6mg per millilitre. Figures for orlistat and liraglutide vary, so your prescriber can advise.

"Poor man's Ozempic" and natural GLP-1

"Natural GLP-1" supplements such as berberine are low-cost supplements with no clinical oversight. They are not medicines, are not regulated for this use and have no comparable trial evidence.¹ Their dosing is not standardised, and we would not describe them as a substitute for a licensed treatment.

Switching between medicines

There is no licensed direct conversion between semaglutide and tirzepatide. Switching is done under prescriber supervision: typically the previous medicine is stopped, a washout interval observed, and Mounjaro started at a dose your prescriber judges appropriate, often the 2.5mg starting dose, sometimes adjusted based on your history.¹ Never run two GLP-1 medicines together.

11 · Starting and using Mounjaro

Starting Mounjaro: doses, titration and long-term use

Mounjaro is taken once a week, and treatment starts at the lowest strength before moving up through the six pens: 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg and 15mg.¹ Your prescriber decides your dose and when to move up, based on how you are doing. Not everyone needs the top dose. Some people settle at 5mg, others at 15mg.

What the first four pens cost

If you step up after 4 weeks on each dose, your first four pens (2.5mg to 10mg) cost £959.96 at standard prices, before discounts. That is a planning figure for the early stage, not a promise that everyone moves up on that schedule. Your prescriber reviews you at each step, and our ongoing monthly clinical reviews are included.

Using the pen

The KwikPen is a pre-filled multi-dose pen. Needles, a sharps bin and injection guidance are included with every order, and the patient leaflet gives step-by-step instructions.¹³ Follow the pen's instructions for the injection itself.

Does the effect last?

In SURMOUNT-4, people who stopped tirzepatide after 36 weeks regained on average 14% of body weight over the following year, while those who continued treatment lost a further 5.5% on average.¹⁴ Because tirzepatide takes roughly 4 to 5 weeks to clear after a final dose, stopping is a gradual change rather than a switch, and planning it with your prescriber is wise. Treatment works alongside a reduced-calorie diet and increased physical activity, and those habits are what you carry with you either way.

Why a regulated pharmacy matters

The difference between "tirzepatide" and Mounjaro is largely a difference in assurance. With a regulated UK pharmacy you get a prescriber review, genuine KwikPens from Eli Lilly's UK distribution, cold-chain delivery, and follow-up. We supply through official LillyDirect, and have supported over 100,000 customers on their weight loss journey. Declined consultations are refunded automatically in full. Dispensed prescription medicines cannot be returned except faulty, damaged or wrong items (contact us within 3 days), and refunds take 5 to 10 working days.

If you are ready to see whether you are suitable, the next step is the free consultation on the Mounjaro pen page. Payment is taken when you place the order; if the prescriber decides the treatment is not suitable, the order is refunded automatically in full.

12 · Serious side effects

Serious side effects: when to get help straight away

Serious side effects are uncommon but need urgent attention. 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. 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.¹ There is no proven way to prevent pancreatitis or gallbladder problems while taking Mounjaro. If you have thoughts of harming yourself or ending your life, get help straight away: call 999 or go to A&E if you are in immediate danger, call NHS 111 and choose the mental health option, or call Samaritans free on 116 123.