Prescription Drugs to Aid Weight Loss in the UK (October 2026)

01 · The options

Which prescription drugs aid weight loss in the UK?

The prescription drugs most often used to aid weight loss in the UK today are injectable GLP-1-based medicines: tirzepatide, semaglutide and liraglutide. Oral options now exist too. All of them are used alongside a reduced-calorie diet and more physical activity, never instead of them.

Older options such as orlistat also exist; your prescriber can advise. Stimulant-type medicines are a separate and different category, which we cover in our guide to amphetamine drugs for weight loss. For a fuller run-down, see our list of prescription weight loss drugs.

02 · Choosing

Is there a best prescription drug for losing weight?

There is no single best drug for everyone; the right choice depends on your BMI, health conditions, current medicines and preferences, and a prescriber makes that call.

Practical questions matter as much as headline results. Do you prefer a weekly pen or a daily one? Are tablets more appealing than injections? Can you stay on treatment long term? Our guide to the injection to aid weight loss explains the injectable route, and our overview of prescription drugs used for weight loss goes wider.

03 · Cost

What do weight-loss prescription drugs cost privately?

The Mounjaro pen costs £169.99 per month at the 2.5mg starting dose, £218.99 at 5mg, £279.99 at 7.5mg, £290.99 at 10mg, £319.99 at 12.5mg and £329.99 at 15mg. These are standard prices for one four-week pen. All six doses are in stock.

Discounts sit on top of those standard prices. A new customer gets £40 off their first order at any dose with code FIRST40, including people switching to us at a higher dose. Every later order is £25 off the standard price automatically (code DOSE25). Your first 2.5mg pen therefore costs £129.99 with the first-order code, and switching at 15mg means a first order of £289.99.

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 of 13 pens costs £2,711.88 if you settle at 5mg, up to £3,599.88 at 15mg, again before discounts. If you settle at 7.5mg, 10mg or 12.5mg, work from that dose's monthly price instead. Consultation is free and the price shown is the price paid, with no hidden fees.

Across the UK pharmacies we track (checked 10 October 2026), Mounjaro pens range from £143.96 to £339.00 per month depending on dose and provider. The 2.5mg starting pen alone runs from £143.96 to £179.99. For the same dose, the gap between providers ranges from £27 to £41, so comparing is worthwhile. Boots' Mounjaro doses run from £179.00 to £339.00.

For Wegovy, your first pen is £99.99 as a first-order price. Tablet prices are not quoted here; see current prices on the product page.

04 · Ordering

How ordering a weight-loss prescription works

Payment is taken when you place the order; if the prescriber decides the treatment is not suitable, the order is refunded automatically in full.

• Free online consultation: a short health questionnaire, no charge and no obligation. Start your free consultation.
• Prescriber review: a GPhC-registered prescriber reviews your answers, not a scoring script. Unsuitable orders are refunded automatically.
• Dispensing and delivery: our registered pharmacy dispenses it, with same-day dispatch when ordered by 3pm and free next-day tracked delivery in temperature-controlled packaging. Saturday delivery is £14.99.

Supply is official LillyDirect stock, sourced directly from Eli Lilly's UK distribution, and monthly clinical reviews are included. Repeat orders re-check suitability and nothing ships automatically.

05 · Who is eligible

Who can be prescribed weight-loss medicine?

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. Qualifying conditions include high blood pressure, high cholesterol, obstructive sleep apnoea, cardiovascular disease, prediabetes and type 2 diabetes.¹

It must be used alongside a reduced-calorie diet and increased physical activity. A prescriber assesses your BMI, medical history and current medicines before deciding whether it suits you.¹¹ That assessment is the real gatekeeper: meeting the number is not the same as being suitable.

Bring a complete list of your medicines to the consultation. For example, tirzepatide can reduce the absorption of oral contraceptives because it slows stomach emptying, and if you take insulin or sulfonylureas, doses may need adjusting because of the risk of low blood sugar.⁷ 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 Mounjaro must not be used during pregnancy, and it should be stopped at least one month before trying to conceive. If you become pregnant during treatment, stop the medicine and tell your prescriber promptly.

06 · Mounjaro evidence

What the Mounjaro trial data show

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 and individual results vary.

For someone starting at 100 kg, 20.9% is about 21 kg. Your own result will depend on your dose, diet, activity and how your body responds, so trial averages do not predict your own result.

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

07 · How it works

How Mounjaro works and what happens when you stop

Tirzepatide activates the GIP and GLP-1 receptors together. These help regulate appetite, slow how quickly the stomach empties and improve how the body responds to insulin. In practice most people feel fuller sooner and less hungry between meals, which supports a reduced-calorie diet.¹

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 Mounjaro manages weight; it does not cure the biology behind it. 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. Stopping should always be planned with your prescriber, with diet and activity habits ready to carry the load. If you are thinking about stopping any weight-loss medicine, discuss it with your prescriber first.

If side effects, cost or convenience are an issue, speak to your prescriber before changing anything.

08 · NHS access

Who qualifies for Mounjaro on the NHS?

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. 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 wait. Your GP is the right first call to ask where you fall in your area's rollout. NHS access to Wegovy runs through specialist weight-management services; ask your GP.

If you are weighing up NHS against private, the licensed criteria for private prescribing are broader than the NHS starting groups, but private treatment is paid for by you. Our top-selling weight loss prescription drugs for 2026 and weight loss prescription drugs in 2022 pages show how the picture has changed.

09 · Buying safely

How to buy prescription weight-loss drugs safely

Only buy from a pharmacy that appears on the GPhC register and asks for a consultation and prescription.¹² Our registration number is 9012878, and you can check it on the register. Be wary of any seller offering to supply without a consultation or prescription, or promising specific results; the MHRA publishes counterfeit medicine alerts.⁷

Low-cost supplements marketed as natural alternatives are not prescription medicines: they come with no clinical oversight and dosing is not standardised. They are not equivalent to the medicines above.

If you experience a side effect, tell your prescriber and report it through the MHRA Yellow Card scheme.¹⁹ If you are also looking at medicines marketed for energy, see our guide to prescription drugs for energy and weight loss. Mounjaro is a prescription-only medicine supplied after an online consultation reviewed by a GPhC-registered prescriber. This page is information, not a substitute for medical advice.

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