Are All Weight Loss Drugs Injections? (October 2026)

01 · The short answer

Which weight loss drugs are injections, and which are not?

The most widely discussed prescription weight loss drugs in the UK are injections, but they are not the only form.

For a wider look at the injectable group, see our weight loss injections guide or the full list of injectable options.

02 · If you choose Mounjaro

What does Mounjaro cost, and what do you get?

The Mounjaro pen costs £169.99 per month at the 2.5mg starting dose, rising to £329.99 at 15mg, as of October 2026. Each pen holds four weekly doses. All six strengths are in stock, supplied through official LillyDirect supply direct from Eli Lilly.

A new customer's first order is £40 off at any dose with code FIRST40, so a first 2.5mg pen costs £129.99 (standard price £169.99). Every later order is £25 off the standard price with code DOSE25.

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 if you settle at 5mg, up to £3,599.88 at 15mg. Those totals are before discounts. Across the UK pharmacies we track, Mounjaro pens range from £143.96 to £339.00 per month depending on dose and provider (index checked 10 October 2026).

The consultation is free, and the price shown is the price paid. Free next-day tracked delivery is included in temperature-controlled packaging, with same-day dispatch when you order by 3pm. Needles, a sharps bin and injection guidance come with every order.

03 · How ordering works

How do you get a weight loss injection from us?

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. If an order is unsuitable it is refunded automatically.
• Dispensing and delivery. Our registered pharmacy dispenses your pen and sends it by free next-day tracked delivery.

Repeat orders re-check suitability, and nothing ships automatically. Monthly reviews and side-effect support are part of the aftercare. If you would rather compare every route first, our overview of weight loss treatments is a good place to begin.

04 · Injections explained

Why are so many weight loss drugs injections?

Several weight loss medicines are injected because they are given under the skin on a set schedule. Mounjaro is 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

Tirzepatide activates 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. Most people feel fuller sooner and less hungry between meals, which supports a reduced-calorie diet.¹

The weekly schedule is one practical reason people choose this route: one injection, on the same day each week. By contrast, liraglutide products such as Saxenda are daily injections. If you want a name-by-name list, see what the weight loss injections are called, or compare weight loss drug injections more broadly.

On results, in the SURMOUNT-1 trial of 2,539 adults, people 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. These are trial averages and individual results vary.² For someone starting at 100 kg, 20.9% is about 21 kg.

05 · Using Mounjaro day to day

What is it actually like to use a weekly pen?

Mounjaro is injected under the skin once a week, on the same day each week, at any time of day, with or without food. Licensed sites are the stomach area (at least 5cm from the belly button), the front of the thigh, or the back of the upper arm if someone else gives the injection. Rotate the site with each dose, and each KwikPen contains four weekly doses.¹

You set the dose by turning the dose knob until the correct dose shows in the window. Follow the pen's instructions for the injection itself.

There is no best time of day: it works the same morning or evening. Many people choose a weekend morning so early side effects fall on days off.¹ If you miss a dose, take it as soon as you can within 4 days (96 hours) of the scheduled time. After more than 4 days, skip it and take the next on your normal day, and never take two doses within 3 days of each other.¹

Storage matters: keep pens in a fridge at 2–8°C and never freeze them. Once in use, a pen can be kept not above 30°C out of the fridge for up to 30 days, then discarded.¹³

06 · Dose and pace

How does the dose build, and how fast are results?

Everyone starts on 2.5mg once a week, and that starting dose is about letting your body adjust rather than weight loss itself. After at least 4 weeks the dose increases to 5mg, then can step up by 2.5mg at minimum 4-week intervals (7.5mg, 10mg, 12.5mg) to a maximum of 15mg weekly. Many people settle at 5mg, 10mg or 15mg, and higher is not automatically better.¹¹¹

Weight loss is gradual by design. Losses on 2.5mg are usually modest, and most measurable progress builds from 5mg onward, month by month. The trials measured results at 72 weeks, so think in months, not days, and judge progress by trend rather than single weigh-ins.¹

Some people notice appetite change in week one, others feel little until a higher dose, and both are normal. Early loss includes water weight.¹³ If you have lost less than 5% of your starting weight after 6 months on the highest dose you can tolerate, your prescriber will discuss whether continuing or stopping is right for you.¹

07 · Who it is licensed for

Who can have 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 such as high blood pressure, high cholesterol, obstructive sleep apnoea, cardiovascular disease, prediabetes or type 2 diabetes. It must be used alongside a reduced-calorie diet and increased physical activity. A prescriber assesses your BMI, medical history and current medicines first.¹¹¹

On the NHS, Mounjaro is available 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 primary-care rollout began in June 2025 with the highest-need groups first, initially BMI 40+ with four or more qualifying conditions. Full rollout is expected to take years, which is why many people who meet the licensed criteria choose regulated private treatment.⁴⁵⁶

NHS access to Wegovy runs through specialist weight-management services; ask your GP.

08 · Alternatives and supplements

What are the alternatives to weight loss injections?

Alternatives include prescription tablets such as Wegovy tablets and Foundayo, the oral medicine orlistat, and lifestyle-led programmes. Figures vary, and your prescriber can advise on suitability. Tablets and injections should not be compared as though one trial's numbers can be set beside another's.

Supplements are different. Products marketed as "nature's Ozempic" or the "poor man's Ozempic", usually berberine, are low-cost supplements with no clinical oversight, and dosing is not standardised. Dramatic weight-loss claims on such products should be treated with caution, and they are not an established substitute for a licensed medicine.

Be wary of anyone offering to supply a prescription injection without a consultation or prescription. Counterfeit pens are a real risk, so buy only from a pharmacy listed on the GPhC register; ours is 9012878. You can read about amphetamine-type drugs for weight loss if you have seen them mentioned, and about nausea in whether all weight loss drugs cause nausea.

09 · Downsides to weigh up

What are the downsides of weight loss injections?

The commonest early effects are mild nausea, altered appetite and tiredness in the first days after each injection, and they usually settle.¹³ The most common side effects are digestive: nausea, diarrhoea, vomiting, constipation and abdominal discomfort affect more than 1 in 10 people. They are most likely when starting treatment or moving up a dose, and for most people they ease within days to a few weeks.

Tirzepatide can reduce absorption of oral contraceptives because stomach emptying slows, so ask your prescriber about contraception.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 If you take insulin or sulfonylureas, doses may need adjusting because of the risk of low blood sugar.¹

Other practical downsides are cost, weekly self-injection, and the fact that tirzepatide has a half-life of about five days, so after a final dose it takes roughly 4–5 weeks to clear the system.¹ Report any new symptom to your prescriber and via the Yellow Card scheme.¹⁹

Our weight loss drugs pharmacy page explains how our prescribing team supports people through monthly reviews, and our GLP-1 injections explainer covers how that drug class is delivered.

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