Reta Weight Loss vs Mounjaro: What UK Adults Need to Know (October 2026)

01 · The verdict

Which should you choose: reta or Mounjaro?

For anyone in the UK who wants a regulated, prescriber-supervised route, Mounjaro is the choice, because retatrutide has no UK licence and cannot be lawfully supplied by a regulated pharmacy for weight loss.¹

Mounjaro suits adults who meet the licensed criteria and want a once-weekly injection with large trial datasets behind it. Retatrutide, as a name you will see online, suits nobody who wants a regulated supply chain, because there is none. If a seller offers it, you are buying outside the licensed pathway.

Many readers arrive from forums and social posts asking whether reta is better than Mounjaro. No trial has compared retatrutide with Mounjaro, so there is no evidence to say either way.

02 · Side by side

Reta vs Mounjaro comparison table

You can see the live Mounjaro pen prices and start a consultation. New customers save £40 on their first order with code FIRST40, and an automatic £25 reorder discount applies to every future order (code DOSE25).

03 · Deciding

The decision factors that actually matter

The first factor is legality and traceability. A licensed medicine has a manufacturer, batch tracking and a regulator. A "research peptide" has none of these, and the MHRA runs counterfeit medicine alerts for good reason.⁷ If the vial is mislabelled, under-dosed or contaminated, you have no recourse.

The second is evidence you can read. Tirzepatide's results are published, peer-reviewed and describe who was studied and for how long.²

The third is supervision. A GPhC-registered prescriber reviews your suitability, you step up the dose in a planned way, and you have monthly reviews and side-effect support. That structure matters more than a few percentage points on a headline chart.

The fourth is cost. Because retatrutide has no regulated UK supply, there is no comparable price to weigh. Mounjaro's cost is transparent: 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 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; a new customer's first order is £40 less and every later order £25 less.

04 · Retatrutide's UK status

What is retatrutide, and why is it not available in the UK?

Retatrutide has no UK licence, so it cannot be prescribed or dispensed by a regulated UK pharmacy for weight loss.⁷ It is an investigational medicine, which is different from an approved one: approval means a regulator has assessed quality, safety and effectiveness for a defined use and population.

That is why you will see it sold as a "research" peptide. Products marketed that way sit outside the licensed pathway. There is no pharmacist checking the contents, no prescriber reviewing your medical history, and no established safety data for using it alongside other treatments.

Online, the shorthand "reta" makes the product sound casual. It is not a supplement or a lifestyle product. If you want a plain-English walk-through of the naming and the difference between the two, our guide to the difference between Mounjaro and reta covers it.

If you see a dramatic weight-loss claim, treat it as marketing until a licensed product exists with a published label.

05 · Mounjaro evidence in full

What the Mounjaro trial evidence shows

Mounjaro is tirzepatide, a once-weekly injection made by Eli Lilly and licensed in the UK for adult weight management and for type 2 diabetes.¹ It activates two natural gut-hormone receptors at once, GIP and GLP-1, which together help regulate appetite, slow how quickly the stomach empties and improve the way the body responds to insulin.¹ In practice most people feel fuller sooner and less hungry between meals, which supports a reduced-calorie diet.

In SURMOUNT-1, 2,539 adults 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 more physical activity, not instead of them.

As a worked example, for someone starting at 100 kg, 20.9% is about 21 kg. That is straight arithmetic on a trial average, not a forecast for you.

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%.²

SURMOUNT-5 was the first large head-to-head trial against semaglutide. Over 72 weeks, adults on tirzepatide lost on average 20.2% of body weight versus 13.7% on semaglutide 2.4mg (Wegovy).¹⁵ Average loss was 22.8 kg versus 15.0 kg, and 48.4% on tirzepatide lost at least 20% of body weight versus 27.3% on semaglutide.¹⁵ Both are effective, licensed treatments; which suits you depends on your health profile, tolerance and prescriber advice.

Notice what is missing: any equivalent, licensed head-to-head with retatrutide. When people ask how reta compares with Mounjaro, the answer rests on what a regulator has reviewed, and that only exists for one of them.

06 · Mixing and swapping

Can you swap from reta to Mounjaro, or use both?

You must not use both: Mounjaro must not be combined with other GLP-1 medicines, unlicensed "research" peptides such as retatrutide, or compounded copies.⁷ These combinations have no safety data and no regulated supply chain. If something promises faster results outside a licensed pathway, that is the warning sign.

If you have been using an unlicensed peptide and want to move to a regulated medicine, the starting point is an honest conversation with a prescriber about what you took, in what amounts and for how long. Your prescriber decides when and whether to switch and which dose to start on.

For comparison, this is how switching from semaglutide (Wegovy/Ozempic) to Mounjaro works. 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 is observed, and Mounjaro is started at a dose your prescriber judges appropriate, often the 2.5mg starting dose, sometimes adjusted based on your history. Never run two GLP-1 medicines together.

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

If you are weighing up similar queries, our pages on choosing between reta or Mounjaro and the reta peptide versus tirzepatide go through the same safety position from different angles.

07 · Natural and cheaper options

"Natural Ozempic", supplements and tablets: what is real?

No supplement is a natural Ozempic. "Natural GLP-1" products such as berberine are not medicines, are not regulated for this use and have no comparable trial evidence. They are low-cost supplements with no clinical oversight, and dosing is not standardised. Names like "poor man's Ozempic" are marketing phrases, not medical categories, and you cannot mimic a prescription GLP-1 medicine with a shop-bought product.

Ozempic itself 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), so "Mounjaro vs Ozempic" for weight loss is really Mounjaro vs Wegovy, and a regulated UK pharmacy will not supply Ozempic for weight loss.¹

What about a pill? There is no tablet form of Mounjaro; tirzepatide is injection-only in the UK. Two GLP-1 weight-loss tablets are now licensed: Wegovy tablets (oral semaglutide, approved by the MHRA in June 2026) and Foundayo (orforglipron, made by Eli Lilly, approved in August 2026).²⁰²¹ They are different medicines with their own dosing, eligibility checks and trial results, and both are prescription-only. Their trial results should not be set against Mounjaro's as if head to head. See the full range of weight loss treatments for current options.

Other licensed options work differently. Orlistat is a tablet that blocks some dietary fat absorption and produces smaller average losses. Wegovy and Saxenda (liraglutide) are other licensed injectables; liraglutide is a daily injection, unlike once-weekly Mounjaro and Wegovy.

08 · Mounjaro vs Wegovy

If not reta, is Wegovy the alternative?

Wegovy (semaglutide 2.4mg) is the other licensed injectable for weight management. In the STEP 1 trial, adults on semaglutide 2.4mg lost on average 14.9% of body weight over 68 weeks, compared with 2.4% on placebo.⁹ In STEP 1, 86.4% lost at least 5% of body weight, 69.1% at least 10% and 50.5% at least 15%.⁹

Gastrointestinal side effects were reported by 74.2% of people on semaglutide 2.4mg versus 47.9% on placebo in STEP 1, and 7.0% stopped treatment because of side effects, compared with 3.1% on placebo.⁹

Wegovy titration runs 0.25mg, 0.5mg, 1mg, 1.7mg and then 2.4mg, stepping up after at least four weeks and reaching the 2.4mg maintenance dose from week 17.¹⁸ The first large head-to-head trial of Wegovy against tirzepatide is SURMOUNT-5. You can view the Wegovy pen for current prices; the first pen costs £99.99 on a first order.

Choosing between the two is a prescriber conversation about your health profile and tolerance, not a leaderboard. Another comparison some readers find useful is how Wegovy and Mounjaro compare on hair loss.

09 · Speed of results

How fast will you lose weight?

There is no honest way to predict how fast any one person will lose weight. Trial figures are averages over 72 weeks, not timelines.² Individual results vary, and a trial average does not predict your own result.

It also helps to separate weight from fat. A scale number includes water and muscle as well as fat, which is why our guide to fat loss versus weight loss is worth a read before you judge any treatment on speed alone.

The claim that a newer peptide works "faster" is a classic reason people look outside the licensed route. Remember that faster promises outside a licensed pathway are the warning sign, not a feature.

10 · NHS and private access

NHS access to Mounjaro

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.⁴ 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.

That is the real trade-off for most readers: wait for NHS access, pay for a regulated private prescription, or take an unlicensed peptide of unknown quality. The third option is the only one without a safety net.

11 · How ordering works

How to get Mounjaro through EverydayMeds

EverydayMeds is a GPhC-registered UK online pharmacy (registration 9012878), and we supply Mounjaro direct from Eli Lilly's UK distribution through official LillyDirect supply, with all six doses in stock. Ordering takes three steps.

• Free online consultation: a short health questionnaire, no charge and no obligation. Start your free consultation.
• Prescriber review: your answers are reviewed by a GPhC-registered prescriber, not a scoring script. Payment is taken when you place the order; if the prescriber decides the treatment is not suitable, the order is refunded automatically in full.
• Dispatch and delivery: dispensed by our registered pharmacy, with same-day dispatch when ordered by 3pm and free next-day tracked delivery in temperature-controlled packaging. Saturday delivery is £14.99.

Consultation is free and the price shown is the price paid. Ongoing monthly reviews, dose-titration and side-effect support come with treatment, and repeat orders re-check suitability with no auto-shipping. We accept Visa/Mastercard, Klarna and pay-monthly options, with no subscriptions.

12 · Safety and side effects

Safety, side effects and reporting

Mounjaro is a prescription-only medicine, supplied only after an online consultation reviewed by a GPhC-registered prescriber, and used alongside a reduced-calorie diet and increased physical activity. Seek immediate medical help for severe, persistent stomach pain, pain in the upper right abdomen with fever or yellowing of the skin or eyes, or signs of a severe allergic reaction. The patient information leaflet lists the known side effects and what to do about them, so read it before your first dose.¹³

If you notice a new symptom, speak to your prescriber, and report suspected side effects through the MHRA Yellow Card scheme.¹⁹ That reporting system exists for licensed medicines. An unlicensed peptide bought online sits outside it, which is another reason a problem is harder to trace and treat.

This page is information, not a substitute for medical advice. Individual results vary.

13 · 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