Which Prescription Weight Loss Medication Is Best? UK Options Compared (October 2026)

01

The best prescription weight loss medications: the short answer

No single licensed medicine is best for everyone; the right one gives you meaningful, sustained loss with side effects you can tolerate. Tirzepatide (Mounjaro) and semaglutide 2.4mg (Wegovy) are the two licensed weekly injections for weight management in the UK.¹¹⁸ Which suits you depends on your health profile, tolerance and prescriber advice.

Cost is part of the decision, though not the whole of it. The Mounjaro pen starts at £169.99 per month for the 2.5mg starter dose at standard price, and you can see all six strengths on the Mounjaro pen page.

02

The decisions you are actually facing

Most readers face two practical questions: am I a suitable candidate, and do I prefer an injection or a tablet? Suitability is a clinical judgement based on your BMI, any weight-related conditions, your other medicines and your history. A prescriber checks all of this.

The routine question is about daily life. Mounjaro needs one injection a week. Wegovy tablets need a strict empty-stomach routine every morning, while Foundayo has no food or water rules.²⁰²¹ If you dislike needles, a tablet may suit you better.

Be cautious about anything promising faster results outside a licensed pathway. Unlicensed research peptides, compounded copies and supplements marketed as natural versions of GLP-1 medicines have no regulated supply chain and no comparable trial evidence.⁷ Our wider guide to effective prescription weight loss medications goes deeper on that distinction.

Our weight loss clinic starts with a free online consultation reviewed by a GPhC-registered prescriber, with no obligation.

Related guides: Effective prescription weight loss medications 2026 and Affordable weight loss medications 2026 and Glp 1 delivery systems comparison effectiveness and Prescription weight loss medications market and Leading prescription weight loss medications 2026.

03 · How they work

How these medicines work

Many prescription weight loss medicines work by changing appetite signals. Mounjaro is the brand name for tirzepatide, a once-weekly injectable prescription medicine made by Eli Lilly, licensed in the UK for weight management in adults and for type 2 diabetes.¹ It comes as a pre-filled multi-dose pen (KwikPen) in six strengths: 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg and 15mg.

Tirzepatide is the first treatment of its kind to activate two natural gut-hormone receptors at once: GIP and GLP-1. Together these 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. This dual action is what distinguishes Mounjaro from single-action GLP-1 medicines such as semaglutide.

Wegovy contains semaglutide, a single-action GLP-1 medicine given once weekly. Its pens step up through the ladder 0.25mg, 0.5mg, 1mg, 1.7mg and 2.4mg, with 4 weeks on each of 0.25mg, 0.5mg, 1mg and 1.7mg, and the 2.4mg maintenance dose starts from week 17.¹⁸

The oral GLP-1 medicines use the same broad idea in tablet form. Wegovy tablets contain semaglutide, the same active ingredient as the Wegovy injection, taken as one tablet once a day.²⁰ Foundayo contains orforglipron, a once-daily GLP-1 tablet made by Eli Lilly, the maker of Mounjaro.²¹ They are different medicines from Mounjaro, with their own dosing, eligibility checks and trial results.

Orlistat is a different kind of medicine altogether. It is a tablet that blocks some dietary fat absorption and produces smaller average losses than the GLP-1 medicines.¹ Liraglutide (Saxenda, and products such as Erly) is supplied at a concentration of 6mg per millilitre and is a daily injection, unlike once-weekly Mounjaro and Wegovy.

None of these medicines replaces diet and activity. Every licence we describe is for use alongside a reduced-calorie diet and increased physical activity.

One practical point about timing: tirzepatide takes a long time to leave the body. 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

04 · Injection evidence

What the trials show for the weekly injections

The head-to-head SURMOUNT-5 trial compared tirzepatide with semaglutide directly. In SURMOUNT-5, 751 adults took tirzepatide or semaglutide 2.4mg for 72 weeks.¹⁵ In the first large head-to-head trial (SURMOUNT-5), adults on tirzepatide lost on average 20.2% of body weight over 72 weeks versus 13.7% on semaglutide 2.4mg (Wegovy).¹⁵ Both are effective, licensed treatments; which suits you depends on your health profile, tolerance and prescriber advice, not the headline number alone.

The detailed breakdown shows the same direction of travel at every threshold. At least 10% of body weight was lost by 81.6% on tirzepatide vs 60.5% on semaglutide; at least 15% by 64.6% vs 40.1%; at least 20% by 48.4% vs 27.3%; at least 25% by 31.6% vs 16.1%.¹⁵ Average loss was 22.8 kg vs 15.0 kg.¹⁵ These are trial averages, and a trial population is not you.

Wegovy's own pivotal trial remains important context. In the STEP 1 trial, adults on semaglutide 2.4mg (Wegovy) lost on average 14.9% of body weight over 68 weeks, compared with 2.4% on placebo.⁹ In STEP 1, 86.4% of adults on semaglutide 2.4mg lost at least 5% of body weight over 68 weeks, compared with 31.5% on placebo. 69.1% lost at least 10% (vs 12.0%) and 50.5% lost at least 15% (vs 4.9%).⁹

For Mounjaro's own dose-response picture, the main trial is SURMOUNT-1. 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 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

To make that concrete, for someone starting at 100 kg, 20.9% is about 21 kg. That is a worked example of straight arithmetic, not a prediction. These are trial averages — individual results vary, and treatment works alongside a reduced-calorie diet and increased physical activity, not instead of them.²

Why does the head-to-head matter more than comparing two separate trials? Different trials recruit different people, run for different lengths and use different methods. Only a direct comparison removes those differences. Read separate-trial numbers as a sense of scale for each medicine, never as a scoreboard.

05 · Weight loss tablets

The new GLP-1 tablets

Two GLP-1 weight-loss tablets are now licensed in the UK, and they suit people who prefer to avoid injections. Wegovy tablets (oral semaglutide, made by Novo Nordisk) and Foundayo (orforglipron, made by Eli Lilly) are both prescription-only, and both sit alongside rather than replace the injectables.²⁰²¹ There is no tablet form of Mounjaro: tirzepatide is injection-only in the UK.

Wegovy tablets

Wegovy tablets are licensed for weight management in adults with a BMI of 30 or above, or 27 to under 30 with at least one weight-related condition, alongside a reduced-calorie diet and more physical activity.²⁰ Treatment starts at 1.5mg once daily and steps up to 4mg, 9mg and then the 25mg maintenance dose, with at least one month at each dose; the dose can stay at an earlier step if needed.²⁰

The routine is the main practical hurdle. The tablet must be taken on an empty stomach after fasting for at least 8 hours, swallowed whole with a sip of water (up to half a glass, about 120ml), and you then wait at least 30 minutes before eating, drinking or taking other tablets.²⁰ If a dose is missed, skip it and take the next tablet the following day. People on the 2.4mg weekly Wegovy injection can move to the 25mg tablet, starting one week after their last injection.

In the OASIS 4 trial, adults taking semaglutide 25mg tablets for 64 weeks lost on average 13.6% of their body weight, compared with 2.2% on placebo.²² The most common side effects are digestive — nausea, vomiting, diarrhoea, constipation, indigestion and stomach pain — along with headache and tiredness; gallstones and hair loss are listed as common.

Foundayo

Foundayo can be taken at any time of day, with or without food and without water restrictions; the tablet is swallowed whole.²¹ It is licensed for the same adult BMI groups as Wegovy tablets. Treatment starts at 0.8mg once daily, then steps up to 2.5mg and 5.5mg, and then to 9mg, 14.5mg or 17.2mg depending on response and tolerability, with at least 30 days at each dose; 17.2mg once daily is the maximum. If a dose is missed, take it as soon as possible, but never more than one tablet a day.

In the ATTAIN-1 trial of 3,127 adults without type 2 diabetes, people taking the highest dose of orforglipron for 72 weeks lost on average 12.4% of their body weight, compared with 0.9% on placebo; the two lower doses gave 7.8% and 9.3%.²³ The trial used capsules, and the UK 17.2mg tablet corresponds to the highest trial dose, so the tablet and capsule doses are not comparable milligram for milligram. In the trial, 10.3% of people on the highest dose stopped because of side effects, compared with 2.7% on placebo.

Foundayo may make oral contraceptive pills less effective: switch to a non-oral method or add a barrier method for 30 days after starting and for 30 days after each dose increase.²¹

Tablets versus injections

No trial has compared Mounjaro directly with either tablet, so results from separate trials — with different people, durations and doses — should not be set against each other as if they were head to head (SURMOUNT-5 is the trial that compared tirzepatide directly with injected semaglutide).¹⁵ The practical differences matter as much as the averages. Check the product pages for current tablet prices, and read our overview of the prescription weight loss medications market for how the category is changing.

06 · Other licensed options

Orlistat, Saxenda, Ozempic and the rest

Orlistat

Orlistat is a tablet that blocks some dietary fat absorption, and it produces smaller average losses than the GLP-1 medicines.¹

Saxenda and liraglutide

Saxenda (liraglutide) is a licensed injectable. It is supplied at a concentration of 6mg per millilitre and is a daily injection, unlike once-weekly Mounjaro and Wegovy.¹⁸ Figures vary and your prescriber can advise on where it fits for you.

Ozempic

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). So 'Mounjaro vs Ozempic' for weight loss is really Mounjaro vs Wegovy, and a regulated UK pharmacy will not supply Ozempic for weight loss.¹⁸

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

The phrase 'poor man's Ozempic' is usually attached to supplements such as berberine, sold as natural GLP-1 alternatives. These are not medicines, are not regulated for this use and have no comparable trial evidence.¹ They are low-cost supplements with no clinical oversight, and their dosing is not standardised. If cost is the worry, the sensible comparison is between licensed medicines, not between a medicine and a supplement.

Retatrutide and other research peptides

Retatrutide has no UK licence. Mounjaro must not be combined with other GLP-1 medicines, unlicensed 'research' peptides (such as retatrutide, which has no UK licence), or compounded copies. These combinations have no safety data and no regulated supply chain.⁷ If something promises faster results outside a licensed pathway, that is the warning sign. A seller offering to supply without a consultation or prescription is another.

07 · Who qualifies

Who qualifies, on the NHS and privately

Eligibility depends on your BMI, any weight-related conditions and whether you go through the NHS or a regulated private pathway. A prescriber confirms suitability either way, and no online guide can do that for you.

The NHS route

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.

NHS access to Wegovy runs through specialist weight-management services; ask your GP. If you are unsure whether you fit the NHS criteria, your GP is the right first conversation, and it costs nothing to ask.

The licensed criteria for the tablets

For the GLP-1 tablets, the licence is explicit. Wegovy tablets and Foundayo are both licensed for adults with a BMI of 30 or above, or 27 to under 30 with at least one weight-related condition, alongside a reduced-calorie diet and more physical activity.²⁰²¹ BMI is calculated in kg/m², using your height and weight.

The private route

Mounjaro (tirzepatide) is a prescription-only medicine, supplied only after an online consultation reviewed by a GPhC-registered prescriber. It is used alongside a reduced-calorie diet and increased physical activity. Individual results vary.¹ At EverydayMeds, the consultation is free, short and carries no obligation. Payment is taken when you place the order; if the prescriber decides the treatment is not suitable, the order is refunded automatically in full.

Private treatment is not a shortcut around clinical judgement. A prescriber will ask about your health, your other medicines and your routine, and may decline to prescribe if treatment is not appropriate.

Questions a prescriber will usually want answered

• Your height, weight and BMI in kg/m², plus any weight-related conditions.
• Every medicine you take, including insulin, sulfonylureas, warfarin and oral contraceptives.
• Previous weight-loss medicines you have tried and how you tolerated them.
• Your daily routine, which affects whether an injection or a tablet is more realistic.

If you are weighing up where to start, our page on getting prescription weight loss medications through telehealth explains how remote prescribing works in practice.

08 · Safety and side effects

Side effects, safety and interactions

The most common side effects of the GLP-1 medicines are digestive, and they are usually most noticeable when you start or step up a dose.

Wegovy's STEP 1 trial shows the scale clearly. In STEP 1, gastrointestinal side effects were reported by 74.2% of people on semaglutide 2.4mg, compared with 47.9% on placebo. 7.0% stopped treatment because of side effects, compared with 3.1% on placebo.⁹ In other words, digestive effects are common, and a small minority stop because of them.

The tablets show a similar pattern. For Wegovy tablets, the most common side effects are digestive — nausea, vomiting, diarrhoea, constipation, indigestion and stomach pain — along with headache and tiredness; gallstones and hair loss are listed as common.²² For Foundayo, the most common side effects are digestive — nausea, constipation, diarrhoea, vomiting, indigestion and stomach pain.²³ In the trial, 10.3% of people on the highest dose stopped because of side effects, compared with 2.7% on placebo.

Why people stop

Your prescriber can hold you at an earlier step if needed. Talking to your prescriber before stopping is usually better than stopping abruptly, because there may be a simple adjustment.

Which is safer: Ozempic or Mounjaro?

Ozempic and Mounjaro cannot be ranked for safety. Ozempic is licensed for type 2 diabetes rather than weight management, so the useful comparison for weight loss is Mounjaro against Wegovy. Both are licensed after safety assessment, and which has the better risk profile for you depends on your health, other medicines and tolerance. Your prescriber is the right person to weigh that.

If you notice a new symptom, tell your prescriber and report it through the Yellow Card scheme.¹⁹

Interactions

Because Mounjaro slows stomach emptying, it can affect how quickly some oral medicines are absorbed, particularly when you start treatment or increase the dose. Tell your prescriber about everything you take — especially warfarin or other narrow-margin medicines, insulin, or sulfonylureas (where doses may need reducing to avoid low blood sugar). No adjustment is needed for paracetamol.¹ 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

This page is information, not a substitute for medical advice. Report any suspected side effect, and get medical help straight away for anything severe.

09 · Switching and stopping

Switching medicines, stopping and keeping weight off

Switching between GLP-1 medicines is done under prescriber supervision, never by self-directed swapping. If you already take Wegovy or another semaglutide product and want to try Mounjaro, there is no licensed direct conversion between semaglutide and tirzepatide.¹ 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.

Never run two GLP-1 medicines together. That includes a tablet and an injection, two injections or any 'stacking' with unlicensed peptides, because those combinations have no safety data. Switching from the 2.4mg weekly Wegovy injection to the Wegovy tablet is a separate, licensed path: the 25mg tablet starts one week after the last injection.²⁰

What happens when you stop

Tirzepatide takes roughly four to five weeks to clear the system after a final dose, so appetite changes do not vanish overnight.¹

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 Stopping should always be planned with your prescriber, with diet and activity habits ready to carry the load.

Why people change or stop

• Side effects that do not settle at a given dose, which a prescriber may manage by holding the dose.
• A change in routine, such as preferring a tablet to an injection.
• Cost over a longer period, which is worth planning for at the start.
• A medical event or new medicine that changes suitability.

Never improvise doses. Dose stretching, extra doses or splitting pens are not part of any licence and carry real risks. If a dose is missed or you are struggling, contact the prescribing team instead.

Ongoing monthly reviews, dose titration and follow-up assessments by the prescribing team are included with EverydayMeds treatment, and repeat orders re-check suitability, with no auto-shipping.

10 · Cost and buying safely

What it costs and how to buy safely

Cost varies by medicine and dose, and the safest place to buy is a regulated UK pharmacy that requires a prescription. For Mounjaro, a pen lasts four weeks, and the standard price rises with dose. Your first 2.5mg pen costs £129.99 with code FIRST40 (standard price £169.99), and the Mounjaro pen page shows every strength. Prices were checked 11 October 2026.

Planning ahead helps. At standard prices, if you step up after 4 weeks on each dose, your first four pens (2.5mg to 10mg) cost £959.96. A first year costs £2,711.88 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. For a first order, subtract £40; every later order is £25 off the standard price. For other maintenance doses, use the monthly price: £279.99 at 7.5mg, £290.99 at 10mg and £319.99 at 12.5mg.

Price spreads between providers are real. 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. Comparing like for like, the same dose can differ between providers by anything from £27 to £41, so compare doses rather than headline prices.

Spotting unsafe sellers

Counterfeit and unregulated products are a genuine risk in this category. The MHRA publishes counterfeit medicine alerts and runs the Yellow Card scheme.⁷ Treat anything as a warning sign if the seller offers to supply without a consultation or prescription, promises specific results, or sells 'research' peptides. You can check any UK pharmacy on the GPhC register; ours is registration 9012878.¹²

How ordering works

• Free online consultation: a short health questionnaire, no charge and no obligation.
• Prescriber review: a GPhC-registered prescriber reviews it, 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.
• Dispensing and delivery: our registered pharmacy dispenses it, with same-day dispatch when ordered by 3pm, then free next-day tracked delivery in temperature-controlled, discreet packaging. Saturday delivery is £14.99.

Mounjaro is sourced through official LillyDirect supply, direct from Eli Lilly's UK distribution, and all six doses are in stock. Needles, a sharps bin and injection guidance come with every order. Payment is by Visa, Mastercard or Klarna, with pay-monthly options and no subscriptions.

Support is available Monday to Friday, 9am to 5pm, by email at support@everydaymeds.co.uk, account portal chat or phone on 0333 207 0413. Our free GLPTrackr app helps you track your journey on iOS and Android.

11 · 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