Is There a Number One Prescription Weight Loss Drug? (October 2026)

01 · The honest answer

What does "number one" actually mean for weight loss drugs?

"Number one" depends on the measure you choose, and nobody publishes a single official ranking.

In SURMOUNT-1, which enrolled 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, and individual results vary. Treatment works alongside a reduced-calorie diet and increased physical activity, not instead of them.

Mounjaro is also mechanistically different. Tirzepatide activates two gut-hormone receptors at once, GIP and GLP-1, which distinguishes it from single-action GLP-1 medicines such as semaglutide (Wegovy/Ozempic).¹ The first large head-to-head trial of tirzepatide and semaglutide for obesity is SURMOUNT-5.¹⁵

02 · Cost and access

What does Mounjaro cost and how do you get it?

Your first Mounjaro pen at 2.5mg costs £129.99 with code FIRST40; the standard price is £169.99. The new-customer discount applies to a first order at any dose, including people switching to us at a higher dose. After that, an automatic £25 reorder discount applies to every future order (code DOSE25). All six doses are in stock.

Each pen lasts four weeks, so the real planning question is the year, not the pen.

A new customer's first order is £40 less than these figures and every later order £25 less. If you settle at 7.5mg, 10mg or 12.5mg, the monthly prices are £279.99, £290.99 and £319.99 respectively.

Ordering takes three steps. First, complete the free online consultation, a short health questionnaire with no charge and no obligation. Second, your answers are reviewed by a GPhC-registered prescriber; payment is taken when you place the order, and if the prescriber decides the treatment is not suitable, the order is refunded automatically in full. Third, our registered pharmacy dispenses and dispatches the same day when you order by 3pm, with free next-day tracked delivery in discreet, temperature-controlled packaging. You can also browse all weight loss treatments, or go straight to our Mounjaro ordering page.

03 · Ranking weight loss drugs

Why no single weight loss drug is officially number one

No regulator, health service or journal publishes a definitive ranking of prescription weight loss drugs, so any "number one" claim is an interpretation. The most useful way to read the question is to split it into the things people actually care about: how much weight is lost on average, how the medicine is taken, who is allowed to take it, and how easily you can get it.

On average weight loss in a published trial, Mounjaro has shown the following. SURMOUNT-1 reported 15% of body weight lost on 5mg, 19.5% on 10mg and 20.9% on 15mg over 72 weeks, against 3.1% with lifestyle changes alone.² The same trial found that half of participants on 10mg and 57% on 15mg lost at least 20% of their body weight.² Those are results of one trial in one population, and they describe averages, not what any single person will see.

A fair head-to-head needs a trial that gives both medicines to comparable people under the same conditions. For tirzepatide and semaglutide in obesity, that trial is SURMOUNT-5.¹⁵

On convenience, both Mounjaro and Wegovy are once-weekly injections, while liraglutide (sold as Saxenda, and in products such as Erly) is a daily injection supplied at 6mg per millilitre. A weekly pen is simply easier to fit into life than a daily one, though that is a preference rather than a ranking.

On access, the picture is mixed. Mounjaro is available on the NHS, but access is being phased in over several years, so many adults who meet the licensed criteria look at regulated private treatment instead of waiting.⁴

If you are comparing options more broadly, our related guides look at the number one weight loss injection and the number one weight loss medication, and there is a separate page on the number one appetite suppressant.

04 · How tirzepatide works

How Mounjaro works: the dual-action difference

Mounjaro works by activating two natural gut-hormone receptors at once, GIP and GLP-1. Tirzepatide is described as the first treatment of its kind to do this.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. That is useful because it makes a reduced-calorie diet easier to follow, which is the foundation of the licensed treatment. The medicine is not a substitute for diet and physical activity; it is designed to be used alongside them.¹

This dual action is what distinguishes Mounjaro from single-action GLP-1 medicines such as semaglutide, which is the active ingredient in Wegovy and Ozempic.¹

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. It comes as a pre-filled multi-dose pen (KwikPen) in six strengths: 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg and 15mg.¹

One practical point on timing: tirzepatide has a half-life of about five days, so after a final dose it takes roughly 4–5 weeks to clear the system. There is no way to speed this up, and nothing needs doing while it clears.¹

Side effects are covered in the patient information leaflet supplied with your pen. Tell your prescriber about any new or lasting symptom, and report suspected side effects through the MHRA Yellow Card scheme.

05 · SURMOUNT-1 explained

What the SURMOUNT-1 results mean in real numbers

SURMOUNT-1 is the trial behind most headline Mounjaro figures. It enrolled 2,539 adults, who took tirzepatide alongside diet and exercise for 72 weeks.² Participants lost on average 15% of body weight on 5mg, 19.5% on 10mg and 20.9% on 15mg, compared with 3.1% with lifestyle changes alone.

Percentages are easier to judge as worked examples. For someone starting at 100 kg, 15% is about 15 kg, 19.5% is about 19.5 kg and 20.9% is about 21 kg. These are straight conversions of trial averages for a hypothetical starting weight; they are not predictions, and your own result depends on your starting point, dose, diet, activity and health.

The trial also reported how many people crossed useful thresholds. At 72 weeks, 85% of participants on 5mg, 89% on 10mg and 91% on 15mg had lost at least 5% of their body weight.² Half of participants on 10mg and 57% on 15mg lost at least 20% of their body weight.² That 5% threshold is widely used because even modest loss can matter, but your prescriber will talk you through goals that suit you.

A few cautions help you read these numbers honestly. First, they are averages: some people lose more, some less. Trial averages do not predict your own result. Second, the figures are tied to dose; the higher results came on the higher strengths, and not everyone settles at the top dose. Third, they come from people using the medicine as directed with a reduced-calorie diet and more physical activity.

Fourth, a trial figure is not a promise. Your prescriber chooses and adjusts your dose through monthly reviews, based on how you respond and how you feel, rather than aiming at a trial number.

06 · Who qualifies

Who is eligible for Mounjaro for weight loss?

Mounjaro is licensed for weight management in adults with a BMI of 30 or above, or a BMI between 27 and 30 with at least one weight-related condition.¹ Qualifying conditions include high blood pressure, high cholesterol, obstructive sleep apnoea, cardiovascular disease, prediabetes and type 2 diabetes.

It must be used alongside a reduced-calorie diet and increased physical activity. That is part of the licence, not an optional extra, and it matches how the trial results were produced.²

Meeting the BMI threshold does not automatically mean Mounjaro is suitable. A prescriber assesses your BMI, medical history and current medicines before deciding. That is why every order is reviewed by a GPhC-registered prescriber rather than approved by a scoring script, and why repeat orders re-check suitability rather than shipping automatically.

Some practical things to prepare for the consultation:

• Your height and weight, so BMI can be calculated accurately.
• Any weight-related conditions you have been diagnosed with.
• A list of all medicines you take, including over-the-counter products and any contraception.
• Any previous weight-loss treatments you have tried.

On contraception specifically, the medicine can reduce absorption of oral contraceptives because stomach emptying slows, so tell your prescriber what you use. 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, doses may need adjusting because of the risk of low blood sugar, which is another reason your full medicines list matters.

Payment is taken when you place the order; if the prescriber decides the treatment is not suitable, the order is refunded automatically in full. The consultation itself is free, with no obligation.

Age alone is not the criterion in the licence; eligibility is set by BMI and weight-related conditions, assessed for each adult individually.

07 · NHS or private

NHS or private: how do you get Mounjaro?

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. That is why many people who meet the licensed criteria choose regulated private treatment rather than waiting. The two routes are not rivals; they are different doors to the same medicine, and the right one depends on whether you fall in a group the NHS is currently prioritising.

If you are not sure which group you fall into, ask your GP first. They can tell you whether you are likely to be offered NHS treatment in your area, and you lose nothing by asking. For Wegovy, NHS access runs through specialist weight-management services; ask your GP.

If you choose to go private, make sure the pharmacy is genuinely regulated. Ours is GPhC-registered (9012878), and you can check any UK pharmacy on the GPhC public register.¹² We source Mounjaro directly from Eli Lilly's UK distribution through official LillyDirect supply, so you receive genuine KwikPens.

08 · Year cost planning

Planning the cost of a year of treatment

A first year costs £2,711.88 at standard prices if you stay on 5mg after your 2.5mg starting pen, up to £3,599.88 if you step up through every dose to 15mg. Both figures cover 52 weeks and 13 pens, and both are before discounts.

If you step up after 4 weeks on each dose, your first four pens (2.5mg to 10mg) cost £959.96 at standard prices. After that, you continue at the dose your prescriber agrees with you. The monthly standard prices at the middle strengths are £279.99 for 7.5mg, £290.99 for 10mg and £319.99 for 12.5mg.

Discounts change the real figure. A new customer's first order is £40 less with code FIRST40, at any dose. Every later order is £25 off the standard price automatically (code DOSE25). If you are switching to us at a higher dose, your first order at 15mg is £289.99; that is a first-order price, not a monthly one.

Provider prices differ. Across the UK pharmacies we track, the gap between providers for the same dose ranged from £27 to £41 at our check on 12 October 2026, and the 2.5mg starting pen ranged from £143.96 to £179.99. Compare like for like, including what is included: our consultation is free, delivery is free next-day, and needles, sharps bin and injection guidance come with every order.

You can spread the cost: we accept Visa and Mastercard, Klarna and pay-monthly options, and there are no subscriptions, so you reorder only when you choose. Our support team is available Monday to Friday, 9am to 5pm, on 0333 207 0413 or support@everydaymeds.co.uk.

09 · Other options and old drugs

Other weight loss drugs, supplements and older medicines

Wegovy (semaglutide) is a once-weekly injection with a dose ladder of 0.25mg, 0.5mg, 1mg, 1.7mg and 2.4mg, stepping up after at least four weeks and reaching the 2.4mg maintenance dose from week 17.¹⁸ Liraglutide (Saxenda, and products such as Erly) is a daily injection supplied at 6mg per millilitre.

There are also tablet options. Wegovy tablets and Foundayo (orforglipron) are oral GLP-1 medicines; see current Wegovy tablet prices on the product page. Their trial results should not be compared with Mounjaro's as if head to head.

For a weight-loss medicine you take as a tablet or injection, the approach is the same: assessment by a prescriber, use alongside a reduced-calorie diet and increased physical activity, and regular review. Our weight loss treatments overview lists what we offer.

Pages on fen-fen, Belviq and Meridia explain the history for those curious about how earlier weight loss drugs fit in, while a page on the Moderna weight loss drug covers the pipeline question. Medicines in development are not available to prescribe.

Then there are supplements. Phrases such as "poor man's Ozempic" or "nature's Ozempic" are marketing terms for low-cost supplements, such as berberine, sold without clinical oversight. They are not the same as a licensed medicine, they are not assessed by a prescriber, and their dosing is not standardised.

Diet pills sold online deserve the same caution. Check any product against the MHRA's counterfeit medicine alerts, and report suspected side effects or fake products through the Yellow Card scheme.⁷ Never buy a prescription medicine from a seller offering to supply it without a consultation or prescription.

10 · 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

11 · Safe ordering

How to order safely and what to expect after

The safest way to buy a prescription weight loss drug is from a regulated UK pharmacy that requires a consultation and a prescriber's approval. Mounjaro is a prescription-only medicine, supplied only after an online consultation reviewed by a GPhC-registered prescriber. If a seller is offering it without a consultation or prescription, walk away.

Counterfeit pens are a real concern, which is why the MHRA publishes counterfeit medicine alerts.⁷ To protect yourself:

• Check the pharmacy on the GPhC public register; ours is registered number 9012878.
• Buy only from a pharmacy that sources directly from the manufacturer's UK distribution, as ours does through LillyDirect.
• Be wary of social media sellers and prices that look too good to be true.
• Read the patient information leaflet in the box and keep it.¹³

Once your order is approved, our registered pharmacy dispenses it, and it is dispatched the same day if ordered by 3pm. Delivery is free, next-day and tracked by DPD in temperature-controlled, discreet packaging. Saturday delivery is £14.99. Needles, a sharps bin and injection guidance come with every order; follow the pen's instructions for each injection.

Aftercare matters as much as the first box. Our prescribing team carries out ongoing monthly reviews, dose titration and follow-up assessments, with side-effect support. Repeat orders re-check suitability, and there is no auto-shipping, so nothing arrives you did not ask for. You can also track your journey in GLPTrackr, our free companion app for iOS and Android.

If you notice a new symptom, speak to your prescriber, and report suspected side effects through the MHRA Yellow Card scheme.¹⁹ If you have questions before ordering, you can start the free consultation without commitment, or call us during support hours.

Mounjaro (tirzepatide) is a prescription-only medicine, used alongside a reduced-calorie diet and increased physical activity. Individual results vary. This page is information, not a substitute for medical advice.