Difference in GLP-1 Medicines: Tirzepatide, Semaglutide and Others (October 2026)

01 · The short version

Which GLP-1 medicine suits whom?

There is no single "best" GLP-1; the right one depends on your health profile, how you tolerate it and what your prescriber advises. Mounjaro (tirzepatide) and Wegovy (semaglutide 2.4mg) are both effective, licensed UK weight-management injections taken once a week.¹⁵ The headline number should not be your only guide.

Tirzepatide has a six-strength dose ladder from 2.5mg to 15mg, and in SURMOUNT-5, the first large head-to-head trial, it showed the larger average loss.¹ Semaglutide 2.4mg may suit adults whose prescriber prefers a single-action GLP-1 medicine, or who have already tolerated it and are doing well on it. Liraglutide is a daily injection, which some people find less convenient than weekly dosing.

02 · Side by side

Tirzepatide vs semaglutide vs liraglutide at a glance

Only SURMOUNT-5 compares two medicines directly. SURMOUNT-1 and STEP 1 are separate trials with different populations and lengths, so their numbers should not be set against each other.²⁹ Trial averages do not predict your own result.

03 · Deciding

Decision factors beyond the headline number

Start with licensing: both Mounjaro and Wegovy are licensed for weight management in UK adults, whereas Ozempic is not.¹⁸ Next comes tolerability. In STEP 1, gastrointestinal side effects were reported by 74.2% on semaglutide 2.4mg against 47.9% on placebo, and 7.0% stopped treatment because of side effects against 3.1% on placebo.⁹ Your prescriber will weigh your history and medicines against these risks.

Then consider practicalities: weekly versus daily injections, the number of dose steps, and cost over time. The Mounjaro pen starts at £169.99 for the 2.5mg pen at the standard price; a new customer saves £40 on their first order with code FIRST40, and an automatic £25 reorder discount applies to every future order (code DOSE25). All six doses are in stock. Prices checked 10 October 2026.

Whichever route you take, treatment sits alongside a reduced-calorie diet and increased physical activity, not instead of them.² Our free consultation is reviewed by a GPhC-registered prescriber, who will advise on what is appropriate for you.

Related guides: Mb 1 vs glp 1 and Agonisti glp 1.

Related guide: Glp 1 vs mounjaro.

04 · What GLP-1 means

What "GLP-1" actually means

GLP-1 is a natural gut hormone, and it is also the shorthand people use for a whole class of medicines that mimic it. That double meaning is the root of most confusion about the difference in GLP-1. When someone says "I'm on a GLP-1", they usually mean an injectable such as Wegovy or Mounjaro, not the hormone itself.

Medicines in this group activate the GLP-1 receptor. In the case of tirzepatide, the active ingredient in Mounjaro, the receptor activation happens alongside a second one. 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.¹ That is the shared job of the class. What separates one medicine from another is the receptor profile, the dosing schedule, the licence and the evidence behind it.

GLP-1 versus GLP-2 and GLP-3

Readers often ask about the difference between GLP-1, GLP-2 and GLP-3, and whether a GLP-2 is better than a GLP-1. We do not supply GLP-2 or any "GLP-3" product. "Better" only makes sense for a specific condition and a specific licensed product. If you have seen a claim that a different hormone-based product outperforms GLP-1 medicines for weight loss, ask what licence and published trial evidence sits behind it. A prescriber can tell you whether it is a regulated UK medicine at all.

Why "GLP-1" is used loosely

Because tirzepatide also targets GIP, it is strictly a dual agonist rather than a pure GLP-1 medicine. This dual action is what distinguishes Mounjaro from single-action GLP-1 medicines such as semaglutide (Wegovy/Ozempic).¹ Most media and search engines still file it under the GLP-1 umbrella, and for everyday purposes that is fine as long as you remember the extra receptor.

05 · Trial evidence compared

Trial evidence: what the numbers show

The key evidence on the difference between tirzepatide and semaglutide is SURMOUNT-5, 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 Both are effective, licensed treatments, and which suits you depends on your health profile, tolerance and prescriber advice, not the headline number alone.

Looking deeper, SURMOUNT-5 enrolled 751 adults for 72 weeks. At least 10% of body weight was lost by 81.6% on tirzepatide versus 60.5% on semaglutide. At least 15% was lost by 64.6% versus 40.1%, at least 20% by 48.4% versus 27.3%, and at least 25% by 31.6% versus 16.1%. Average loss was 22.8 kg versus 15.0 kg.¹⁵ These are group averages, and individual results vary.

SURMOUNT-1 for tirzepatide

In SURMOUNT-1, 2,539 adults taking tirzepatide alongside diet and exercise lost on average 15% of 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%.²

As a worked example only: for someone starting at 100 kg, 20.9% is about 21 kg.

STEP 1 for semaglutide

In STEP 1, adults on semaglutide 2.4mg lost on average 14.9% of body weight over 68 weeks, compared with 2.4% on placebo.⁹ Of those, 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

How to read these results

Do not line up SURMOUNT-1 and STEP 1 and declare a winner: they were different trials with different participants and durations. Only SURMOUNT-5 supports a direct tirzepatide-versus-semaglutide comparison. Remember too that every figure here assumes a reduced-calorie diet and increased activity alongside treatment.

06 · Dosing and formats

Dosing schedules and formats

The practical differences between GLP-1 medicines start with how often you inject and how many steps the dose ladder has. Mounjaro is a once-weekly injectable made by Eli Lilly, supplied as a pre-filled multi-dose pen (KwikPen) in six strengths: 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg and 15mg.¹

Wegovy (semaglutide) is also once weekly. Its pens are 0.25mg, 0.5mg, 1mg, 1.7mg and 2.4mg, and the dose steps up after at least 4 weeks, reaching the 2.4mg maintenance dose from week 17.¹⁸ The 2.4mg dose is the licensed maintenance dose for weight management.

Liraglutide, sold as Saxenda and in products such as Erly, is supplied at 6mg per millilitre and is a daily injection, unlike once-weekly Mounjaro and Wegovy.

What starting looks like in cost terms

For Mounjaro, 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. A new customer's first order is £40 less, and every later order is £25 less. At standard prices, a first year (13 pens) 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 other maintenance doses, the monthly price is £279.99 at 7.5mg, £290.99 at 10mg and £319.99 at 12.5mg. Your first Wegovy pen is £99.99 as a first-order price. See the Wegovy pen page for current details.

Tablets are a different category

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, 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. They were not tested head to head with Mounjaro, so their trial results should not be set against it.

Storage in brief

Store unopened pens in the fridge until first use; they keep until the printed expiry date. 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 at a temperature not above 30°C for up to 30 days after first use, and must then be thrown away. Do not use a pen that has been above 30°C or has been frozen, and keep the pen cap on to protect it from light. The patient information leaflet and your pharmacy are the right places to ask about anything else.¹³

07 · Licences and diabetes drugs

Licensing: weight loss, diabetes and the Ozempic question

What a GLP-1 is licensed for matters as much as how it works. In the UK, Mounjaro is licensed for weight management in adults and for type 2 diabetes.¹ Ozempic, by contrast, 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.¹⁸

The licensed weight-management options are Mounjaro (tirzepatide) and Wegovy (semaglutide 2.4mg). So "Mounjaro vs Ozempic" for weight loss is really Mounjaro versus Wegovy, and a regulated UK pharmacy will not supply Ozempic for weight loss. Other licensed injectables include Saxenda (liraglutide), and orlistat is a licensed tablet that blocks some dietary fat absorption and produces smaller average losses.

GLP-1 versus gliclazide

People with type 2 diabetes sometimes ask about the difference between a GLP-1 and gliclazide. Gliclazide belongs to the sulfonylurea group, a different class of diabetes medicine from GLP-1 and GIP/GLP-1 injections. 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. This does not mean the medicines must never be used together, but it does mean you should tell your prescriber about every medicine you take.¹³

Why the licence is not a technicality

A licence means a regulator has assessed quality, safety and efficacy for a particular use, and that the product information tells you what to watch for. An off-label or unlicensed route may lack some of that. It is also why unlicensed "research" products are a different matter entirely: they sit outside the regulated supply chain.

If you are unsure which category a product falls into, check that the seller is a registered pharmacy. We are GPhC-registered (9012878), and you can verify that on the GPhC register. Prescription-only medicines such as Mounjaro are supplied only after a consultation reviewed by a GPhC-registered prescriber. Our supply is official LillyDirect, with genuine KwikPens sourced directly from Eli Lilly's UK distribution.

For readers comparing against newer products, our page on retatrutide and tirzepatide explains why a medicine with no UK licence cannot be treated like a licensed option.

08 · Side effects and stopping

Tolerability, side effects and stopping

All GLP-1 medicines can cause gastrointestinal side effects, and the trial figures show this plainly. In STEP 1, gastrointestinal side effects were reported by 74.2% of people on semaglutide 2.4mg, compared with 47.9% on placebo, and 7.0% stopped treatment because of side effects, compared with 3.1% on placebo.⁹

Common side effects include nausea, diarrhoea, vomiting, constipation and abdominal discomfort; your prescriber will discuss them with you.¹³ If you notice a new symptom, speak to your prescriber, and you can report suspected side effects through the MHRA Yellow Card scheme.¹⁹

Do different GLP-1s work differently?

Yes, in two ways. First, the receptor profile differs: tirzepatide acts on GIP and GLP-1, while semaglutide acts on GLP-1.¹ Second, the formats and dose ladders differ. But they share the core effects of helping regulate appetite and slowing how quickly the stomach empties. Because of that shared effect, people sometimes experience similar side effects across the class, though how you personally respond is individual.

What happens when you stop a GLP-1?

Tirzepatide has a half-life of about five days, so after a final dose it takes roughly 4 to 5 weeks to clear the system. There is no way to speed this up, and nothing needs doing while it clears.¹ Stopping should always be planned with your prescriber, who can advise on your diet, activity and any alternative plan. 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 lost a further 5.5% on average.

Our aftercare

Treatment is not just a box that arrives. Our service includes ongoing monthly reviews, dose titration and follow-up assessments by the prescribing team, plus side-effect support. Repeat orders re-check suitability, and there is no auto-shipping. Support is available Monday to Friday, 9am to 5pm, by email at support@everydaymeds.co.uk, via the account portal chat or on 0333 207 0413. The free GLPTrackr app can help you log doses and how you feel week to week, which makes review conversations more specific.

09 · Switching and stacking

Switching, stacking and "cheaper alternatives"

Switching between GLP-1 medicines is a prescriber-led process, not a self-managed one. 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. That includes injecting a second product "to speed things up" or topping up with a tablet from a different brand. A prescriber needs the full picture of what you have taken and when.

Stacking and research peptides

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. If something promises faster results outside a licensed pathway, that is the warning sign. The same logic applies to anyone offering to supply a prescription medicine without a consultation or prescription.

How to speed up weight loss with a GLP-1

The honest answer is that there is no licensed shortcut. Trial averages do not predict your own result.

What is the "poor man's Ozempic"?

The phrase is usually applied to berberine and similar "natural GLP-1" supplements. These are not medicines, are not regulated for this use and have no comparable trial evidence. They are available cheaply without assessment, which is part of the risk: no clinical oversight and dosing is not standardised. Online claims of dramatic weight-loss results from supplements should be treated sceptically.

Other licensed alternatives

If injections are not for you, other licensed options exist. Wegovy and Saxenda (liraglutide) are other licensed injectables, orlistat is a tablet, and two GLP-1 tablets are now licensed. A prescriber can explain which is appropriate.

10 · Serious side effects

Serious side effects: when to get help straight away

Serious side effects are uncommon but need urgent attention. Get medical help straight away 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 · NHS, private and ordering

NHS or private: how access differs

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 about your own eligibility, your GP is the right first conversation, and you can also use the private route in parallel with regulated safeguards.

What private treatment costs

Across the UK pharmacies we track, standard prices for a Mounjaro pen at any dose run from £143.96 to £339.00, checked 10 October 2026. For the 2.5mg starting pen, those pharmacies range from £143.96 to £179.99, and the gap between providers for the same dose runs from £27 to £41. Boots' Mounjaro doses run from £179.00 to £339.00. All of those figures are per month, meaning one 4-week pen.

With us, the standard price of the 2.5mg pen is £169.99, and a new customer's first order is £40 less with code FIRST40. Every later order is £25 off the standard price, applied automatically (code DOSE25). The consultation is free, and the price shown is the price paid, with no hidden fees. Payment options include Visa, Mastercard, Klarna and pay-monthly options, with no subscriptions.

How ordering works

Ordering has four steps. First, a free online consultation: a short health questionnaire, no charge and no obligation. Second, prescriber review 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. Third, dispensing and dispatch by our registered pharmacy, with same-day dispatch when ordered by 3pm. Fourth, free next-day tracked delivery by DPD in discreet, temperature-controlled packaging. Saturday delivery is £14.99. Needles, a sharps bin and injection guidance are included with every order.

When you are ready, start your consultation. Dispensed prescription medicines cannot be returned except if faulty, damaged or the wrong item (contact us within 3 days), and refunds take 5 to 10 working days. Declined consultations are refunded in full.

Over 100,000 customers have been supported on their weight loss journey with us. That is a measure of service, not a measure of how well any medicine will work for you. Mounjaro is a prescription-only medicine, used alongside a reduced-calorie diet and increased physical activity. Individual results vary, and this page is information, not a substitute for medical advice.