GLP-1 Technology Explained: How the Medicines Work (October 2026)

01 · The short answer

What people mean by GLP-1 technology

GLP-1 technology means the engineering that makes a natural gut-hormone signal useful as a treatment. Your body makes GLP-1 in the gut as part of normal digestion, and the signal is short-lived. A medicine has to copy the message, last long enough to be practical and be safe to manufacture at scale. That is the whole technology problem, and each licensed product solves it in its own way.

The medicine we supply is Mounjaro (tirzepatide). 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.¹ It is supplied as a pre-filled multi-dose pen (KwikPen) in six strengths: 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg and 15mg.¹

02 · Compare the formats

GLP-1 delivery formats compared

If you want to explore tablets in more depth, see our guide to oral GLP-1 weight loss.

03 · Your next step

Is this relevant to you, and what next?

If you are considering treatment, the key decision is whether a licensed medicine is appropriate for you, and that is a prescriber's judgement based on your health history.

When you are ready, the Mounjaro online prescription page explains the consultation. Your first 2.5mg pen costs £129.99 with code FIRST40 (standard price £169.99), and every later order is £25 off the standard price. Prices checked 10 October 2026.

Treatment is only supplied after an online consultation reviewed by a GPhC-registered prescriber, and it is used alongside a reduced-calorie diet and increased physical activity. Individual results vary. This page is information, not a substitute for medical advice.¹

Related guides: Glp 1 kvapky uzivanie and Glp 1 assay.

04 · How GLP-1 works

What is GLP-1 and how does it work?

GLP-1 is a natural gut hormone, and GLP-1 medicines are designed to activate the same receptors the hormone uses. Mounjaro helps 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.¹

The technology challenge sits in the gap between the natural hormone and a usable medicine. A hormone that acts briefly in the gut would be impractical as a treatment, because you would need constant dosing. Mounjaro is taken once weekly, not several times a day.

The design of tirzepatide goes a step further than copying GLP-1 alone. Tirzepatide is the first treatment of its kind to activate two natural gut-hormone receptors at once: GIP and GLP-1.¹ This dual action is what distinguishes Mounjaro from single-action GLP-1 medicines such as semaglutide (Wegovy/Ozempic).¹ That is a genuine point of technical difference, though it does not by itself tell you which medicine will suit you better. Only a prescriber can weigh that up with you.

Why does slower stomach emptying matter? It is part of why people feel full for longer after eating. It is also linked to a practical interaction worth knowing about: the medicine can reduce absorption of oral contraceptives, because stomach emptying slows. 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 Your prescriber can explain what to do if that applies to you.¹³

If you take insulin or a sulfonylurea for diabetes, doses may need adjusting because of the risk of low blood sugar. This is a conversation to have with your prescriber before starting, not something to manage alone.¹³

It helps to hold a clear mental model. The medicine does not melt anything away. It changes appetite signalling and digestion speed so that eating less feels more manageable. That is why the licence and the trials both place treatment alongside a reduced-calorie diet and increased physical activity, not instead of them. Anyone promising that a product works without any change in eating or activity is describing something other than the licensed medicines.

Finally, remember that technology is not the same as suitability. A prescriber considers your medical history, current medicines, any pregnancy plans and your goals before deciding whether treatment makes sense. The science explains the mechanism; the consultation decides whether it applies to you.

05 · Injections to tablets

From injection to tablet: how delivery differs

Delivery is where much of the current GLP-1 innovation is happening, and the UK now has several formats. Once-weekly pens are the best known format. Mounjaro is a pre-filled multi-dose pen (KwikPen) in six strengths, and Wegovy is a once-weekly pen with its own dose ladder of 0.25mg, 0.5mg, 1mg, 1.7mg and 2.4mg.¹¹⁸

A daily injection also exists. Liraglutide, sold as Saxenda and in other products, is supplied at a concentration of 6mg/ml and is injected daily, unlike once-weekly Mounjaro and Wegovy.

Tablets are the newest formats. Wegovy tablets contain oral semaglutide, and Foundayo is a film-coated tablet of orforglipron.²⁰²¹ Each has its own product information, and each has instructions about how to take it that you should follow exactly as written in the leaflet. See current Wegovy tablet prices on the Wegovy product page.

Our oral GLP-1 weight loss guide covers which GLP-1 can be taken orally. If you want to see how a weekly pen fits into practical life, the Wegovy pen and Mounjaro product pages set out the formats.

One more point on technology and storage. Pens must be kept cold before use: store in the fridge at 2–8°C until first use, and they keep until the printed expiry date. Once in use, a KwikPen 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.¹³ For any question about unopened pens being out of the fridge, read the patient information leaflet and ask the pharmacy.

The takeaway: format changes how you take the medicine, not the need for a prescriber. Whatever the delivery method, licensed GLP-1 medicines are prescription-only, and each has its own safety information that should be read before starting.

06 · Inside the Mounjaro pen

How Mounjaro is designed to be used

Mounjaro is built around a weekly routine, and its pharmacology explains why. 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

The KwikPen is multi-dose, so a single pen covers several weekly doses. Pens come in six strengths. Treatment normally begins at the lowest strength, and the prescribing team steps the dose up over time. Where you settle afterwards depends on how you respond and tolerate treatment, and that is decided with a prescriber, not by the pen.

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. A new customer's first order is £40 less with code FIRST40, and every later order is £25 less (code DOSE25). For other maintenance doses, the monthly standard prices are £279.99 at 7.5mg, £290.99 at 10mg and £319.99 at 12.5mg. You can see the Mounjaro pen prices and consultation any time; all six doses are in stock.

Storage is part of the design too. Keep unopened pens in the fridge until first use. Once you begin using a pen, it can be kept out of the fridge at a temperature not above 30°C for up to 30 days, then thrown away. Do not use a pen that has been above 30°C or frozen, or one past its printed expiry date.¹³

Pen instructions matter. We include needles, a sharps bin and injection guidance with every order, and you should follow the pen's own instructions for each injection rather than relying on tips from forums.

If you track your journey, the free GLPTrackr companion app is available for iOS and Android, and there is also a printable weight loss tracker for those who prefer paper. Neither changes how the medicine works; they simply make it easier to notice patterns and prepare for reviews.

Our prescribing team provides ongoing monthly reviews, dose titration and follow-up assessments, plus side-effect support. Repeat orders re-check suitability, with no auto-shipping, so the medicine you receive always follows a fresh clinical decision.

07 · What the trials show

What the trial evidence shows, and its limits

The headline trial for Mounjaro in weight management is SURMOUNT-1, and its results are worth reading carefully rather than skimming. 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.²

The trial also reports how many people reached particular 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

How should you read these figures? As a worked example only: for someone starting at 100 kg, 20.9% is about 21 kg. That is arithmetic on a trial average, not a forecast for you. Trial averages do not predict your own result, and some people lose less while some lose more.

Another honest limit is duration. The SURMOUNT-1 results cover 72 weeks, while the STEP 1 semaglutide trial covered 68 weeks, so treatment length in the trials is not the same as in real life. Questions such as how long to take a GLP-1 medicine for weight loss are decided in ongoing reviews with your prescriber, based on how you are doing and what you want.

The trials also tell you nothing about products that were not tested. Where a seller quotes dramatic weight-loss claims for such a product, the right response is scepticism, not excitement.

In short, the evidence for licensed GLP-1 medicines is substantial but averaged. Use it to understand what is possible, then let a consultation decide what is appropriate for you.

08 · Downsides and risks

What is the downside of taking GLP-1?

GLP-1 medicines have real downsides. The most common side effects are digestive: nausea, diarrhoea, vomiting, constipation and abdominal discomfort affect more than 1 in 10 people. Our GLP-1 side effects guide sets out what to expect and how people manage it. Read it before you start, not after.

Other downsides are practical. These medicines are used alongside a reduced-calorie diet and increased physical activity, so they are not effortless. Treatment is ongoing and has costs, and the medicine stays in your body for some time after a stop. The product information notes it takes roughly 4–5 weeks to clear the system, and nothing speeds this up.¹

Some interactions matter. Mounjaro slows stomach emptying, which can reduce how well oral contraceptive pills are absorbed. Switch to a non-oral method, or add a barrier method (such as condoms), for 4 weeks after starting Mounjaro and for 4 weeks after each dose increase.¹³ If you use insulin or a sulfonylurea, doses may need adjusting because of the risk of low blood sugar.¹³

Mood is another area people ask about. Regulators have looked at whether GLP-1 medicines are linked to low mood or suicidal thoughts: the EMA's safety committee concluded in 2024 that the evidence does not support a causal link, and the MHRA keeps this under continuous review.¹⁷ Any big change in weight, appetite and routine can affect how you feel; tell your prescriber about any history of depression, and seek help promptly if your mood drops or you have distressing thoughts during treatment.

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. In England you can call NHS 111 and choose the mental health option, any time. You can also call Samaritans free on 116 123, day or night. Tell your prescriber about any change in your mood while taking Mounjaro.

Tell your prescriber about any new or lasting symptom. You can also report any suspected side effect through the MHRA Yellow Card scheme, which helps regulators monitor safety.¹⁹

Finally, who should not take Mounjaro? You should not take it if you are allergic to tirzepatide or any of its ingredients, and it should not be used during pregnancy or while trying to conceive. Your prescriber will take extra care, or may recommend against treatment, if you have a history of pancreatitis, severe gut or digestive disease, diabetic retinopathy, or gallbladder problems. Mounjaro must not be used during pregnancy, and it should be stopped at least one month before trying to conceive. The online consultation exists so a GPhC-registered prescriber can review exactly those points.

09 · Natural GLP-1 and supplements

Natural GLP-1, supplements, drops and patches

The body produces GLP-1 naturally as a gut hormone, and the receptors that respond to it are natural gut-hormone receptors.¹ So when people ask where GLP-1 naturally comes from or how to get GLP-1 naturally, the straight answer is that your gut already makes it in response to eating. What the medicines do is activate the same receptors in a controlled, tested way.

Can food or supplements replicate that? Be cautious. Eating balanced meals supports normal digestion, but nothing available over the counter has been shown to match a licensed GLP-1 medicine. Products sold with GLP-1 in the name, including prebiotics, patches and oral drops, vary widely. Dosing is not standardised, they carry no clinical oversight, and they are available cheaply without assessment, which is part of the reason to be careful.

The phrase oral liquid causes confusion too. A licensed medicine's leaflet tells you exactly how to take it. For an unlicensed liquid or drop, there is no approved instruction to follow, so there is no reliable way to say how it should be taken. If a seller offers to supply a prescription-only GLP-1 medicine without a consultation or prescription, treat that as a warning sign.

Counterfeit and illegal products are a real concern. The MHRA publishes alerts on counterfeit medicines and runs the Yellow Card scheme for reporting suspected problems.⁷ Check that any pharmacy appears on the GPhC register; ours is registered under GPhC 9012878. We supply Mounjaro through official LillyDirect supply, which means genuine KwikPens sourced directly from Eli Lilly's UK distribution.

The sensible checks are the same for any product: is it licensed, who supplies it, is there a prescriber review, and does the leaflet make sense? If you cannot answer yes to those, do not take it.

None of this means lifestyle is unimportant. Diet and activity remain the foundation, and the licensed medicines are designed to support them, not replace them.

10 · NHS and private routes

NHS and private access to GLP-1 treatment

Access to GLP-1 treatment in the UK runs through two routes, NHS and private, and they differ in timing and eligibility. The honest NHS position is this: 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, 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).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.

If you think you might qualify on the NHS, start with your GP. The NHS guide to tirzepatide explains what the medicine is used for and what to expect.⁵ For Wegovy, NHS access runs through specialist weight-management services; ask your GP.

Private treatment follows a clear journey. You complete a free online consultation, a short health questionnaire with no charge and no obligation. 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. Approved orders are dispensed by our registered pharmacy, with same-day dispatch when ordered by 3pm, and delivered with free next-day tracked delivery in temperature-controlled, discreet packaging. Saturday delivery is £14.99.

Costs are worth planning. Standard prices run from £169.99 at 2.5mg to £329.99 at 15mg per pen, each pen lasting four weeks. A new customer saves £40 on their first order at any dose with code FIRST40, including people switching from another provider at a higher dose, and an automatic £25 reorder discount applies to every future order (code DOSE25). Across the UK pharmacies we track, Mounjaro pens ranged from £143.96 to £339.00 as of 10 October 2026. Payment is by Visa or Mastercard, Klarna or pay-monthly options, and there are no subscriptions.

Which route is right? NHS care brings no medicine charge beyond the usual rules, but waiting times and eligibility limits apply. Private care is faster but you pay. Neither choice is wrong, and some people use both over time. Whichever you choose, the clinical safeguards should be the same: a prescriber's review, clear information and follow-up.

Support is available Monday to Friday, 9am to 5pm, by email at support@everydaymeds.co.uk, through the account portal chat or by phone on 0333 207 0413. For a broader look at our service, see the weight loss clinic.

11 · Quality and what to check

Quality, supply and what to check before buying

With any GLP-1 product, quality depends on supply, and the supply chain is where unlicensed sellers cut corners. The first check is the pharmacy. The GPhC publishes a public register of pharmacies, and you can look up any seller on it.¹² Ours is registered under GPhC 9012878, and the register link is on our site.

The second check is the product. Genuine Mounjaro comes as a KwikPen in six strengths and arrives with patient information. We source it through official LillyDirect supply, directly from Eli Lilly's UK distribution, with all six doses stocked from 2.5mg to 15mg. If a seller offers pens in unusual formats, vials or powders, or offers to supply without a consultation or prescription, walk away. The MHRA publishes counterfeit medicine alerts, and you can report suspect products or side effects through the Yellow Card scheme.⁷¹⁹

The third check is the service around the product. A good provider offers a free consultation reviewed by a GPhC-registered prescriber, clear information on how to inject, and follow-up. Aftercare matters because dose steps, side effects and goals change over time. We provide ongoing monthly reviews, dose-titration and follow-up assessments, and side-effect support. Repeat orders re-check suitability, so nothing ships automatically.

The fourth check is honesty about results. A provider that promises specific outcomes is not describing the evidence. Trial averages do not predict your own result, and anyone who tells you otherwise is selling, not informing.

Refunds are worth knowing about before you order. Declined consultations are refunded automatically in full. Dispensed prescription medicines cannot be returned except for faulty, damaged or wrong items, which should be reported within three days, and refunds take five to ten working days. Consultation is free, the price shown is the price paid, and there are no hidden fees.

What about unfamiliar technology claims, the kind that appear in adverts and social posts? Treat the wording as a prompt to check, not a reason to trust. A genuine licensed medicine has an SmPC and a patient leaflet you can read for free. If those do not exist, or you cannot find them, the product has no licence behind it.

If you want to see how this plays out in practice, the Mounjaro GLP-1 online prescription page explains the consultation, and you can ask our support team anything before you decide. Nothing here replaces advice from your own prescriber or GP.

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