LICENSED PHARMACY & UK-LICENSED DOCTORS · FREE DISCREET DELIVERY
TIRZEPATIDE · ELI LILLY · ONCE-WEEKLY INJECTION
Free discreet delivery
*Individual results vary; all results were achieved alongside diet and lifestyle change.
Mounjaro is a once-weekly injection and the first treatment of its kind to activate two appetite-regulating hormone receptors — GIP and GLP-1. In its pivotal trial, adults lost over 20% of their body weight on average at the highest dose, the strongest result of any licensed weight loss medicine in the UK.
ABOUT THE MEDICATION
Mounjaro is the brand name for tirzepatide, developed by Eli Lilly. It was licensed by the MHRA for weight management in adults in late 2023, having first been licensed for type 2 diabetes, and has since become the most prescribed weight loss injection in the UK private market.
It is licensed for adults with a BMI of 30 kg/m² or above, or 27 kg/m² and above with at least one weight-related condition, always alongside a reduced-calorie diet and increased physical activity. Mounjaro is not a quick fix or a cosmetic product: it is a medical treatment for the chronic condition of obesity, prescribed and monitored by clinicians.
KEY BENEFITS
Tirzepatide is the first licensed medicine to mimic both GLP-1 and GIP, and this dual action is widely credited for its stronger results.
Tirzepatide is engineered to break down slowly, which is why one injection lasts a full week with steady effect — no daily peaks and troughs.
Average weight loss was approximately 15% at 5 mg, 19.5% at 10 mg and 20.9% at 15 mg, versus around 3% with placebo.
Tirzepatide also improved blood pressure, cholesterol and triglycerides, waist circumference and physical function scores.
GLP-1 weight loss treatments are licensed for adults who meet one of the following criteria, alongside a reduced-calorie diet and increased physical activity:
BMI thresholds may be adjusted for people from South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean backgrounds, who are at higher cardiometabolic risk at lower BMIs.
Meeting the BMI criteria alone doesn't guarantee suitability — our prescribers review your full medical history. GLP-1 treatments are not suitable during pregnancy or breastfeeding, or for people with a personal or family history of medullary thyroid carcinoma or MEN 2, among other contraindications your prescriber will assess.
Basic Info
What is your height?
What is your weight?
Dual GIP and GLP-1 agonist
Once-weekly subcutaneous self-injection
Greater weight loss than semaglutide 2.4 mg
2.5 mg start, 4-week dose steps
TRIAL WEIGHT LOSS RESULTS
20.9%
average weight loss at 15 mg over 72 weeks — SURMOUNT-1 trial
Cross-trial figures are not head-to-head comparisons unless stated (SURMOUNT-5 is). Individual results vary; all results were achieved alongside diet and lifestyle change.
The Device
In the UK, Mounjaro is supplied as the KwikPen — a pre-filled, multi-dose pen containing four weekly doses. Each strength (2.5 mg to 15 mg) has its own pen, and one pen lasts a month. The injection itself takes seconds, uses a very fine needle, and most patients describe it as painless or close to it.
Mounjaro is not a quick fix or a cosmetic product: it is a medical treatment for the chronic condition of obesity, prescribed and monitored by clinicians.
After you eat, your gut releases hormones that tell your brain you're full and help your body process the meal. Two of the most important are GLP-1 (glucagon-like peptide-1) and GIP (glucose-dependent insulinotropic polypeptide). In many people living with obesity, the appetite-signalling side of this system is blunted — hunger shouts louder than fullness.
How It Works
Most weight loss injections mimic GLP-1 alone. Tirzepatide is the first licensed medicine to mimic both GLP-1 and GIP, and this dual action is widely credited for its stronger results. In practice, patients notice four things:
You feel satisfied with smaller portions, and the urge to snack fades.
The intrusive, constant thinking about food that many patients describe simply turns down.
Meals keep you full for hours longer, so you naturally eat less across the day.
Improved insulin sensitivity and blood sugar control, with GIP also thought to influence how the body stores and uses fat.
Step by step
Wash your hands, check the pen label and expiry, and confirm the liquid is clear and colourless to slightly yellow.
Attach a new needle for every injection, remove both needle caps, and on a new pen check the flow as instructed in the leaflet before your first dose.
Dial your dose, choose a site — stomach (at least 5 cm from the navel), front of thigh, or back of upper arm — and clean the skin.
Insert the needle fully at 90 degrees, press and hold the dose button, and count slowly as directed in the pen instructions until the dose counter returns to 0.
Remove, dispose of the needle in your sharps bin (supplied), and recap the pen without a needle attached.
Rotate injection sites each week, and inject on the same day each week — the day itself can be changed provided at least 3 days (72 hours) separate two doses.
Side Effects
Nausea, diarrhoea, constipation, vomiting
Indigestion, reflux, bloating, burping, reduced appetite beyond intended, fatigue, dizziness, hair shedding, injection-site reactions
Gallstones, gallbladder inflammation, raised heart rate, low blood sugar (mainly with diabetes medicines)
Pancreatitis, severe allergic reaction, severe dehydration/kidney injury from prolonged vomiting
Most side effects are digestive, dose-related and temporary — clustering in the first weeks and after each dose increase, then settling. In SURMOUNT-1, discontinuation due to side effects was uncommon (around 4–7% across doses). Surgery and procedures: tell any clinician you're taking Mounjaro before planned surgery or sedation — slowed stomach emptying can leave residual stomach contents, and anaesthetists may ask you to pause treatment beforehand. Report suspected side effects via the MHRA Yellow Card scheme.
The Evidence
20.9%
average weight loss at 15 mg over 72 weeks, versus around 3% with placebo
SURMOUNT-1 enrolled 2,539 adults with obesity (or overweight plus a weight-related condition) without diabetes, treated for 72 weeks alongside lifestyle support. Average weight loss was approximately 15% at 5 mg, 19.5% at 10 mg and 20.9% at 15 mg. Around nine in ten participants on tirzepatide lost at least 5% of their body weight, and roughly a third of those on the highest dose lost 25% or more.
~20%
versus roughly 14% with semaglutide 2.4 mg over 72 weeks
In the first major head-to-head trial of the two leading injections, tirzepatide produced significantly greater average weight loss than semaglutide 2.4 mg over 72 weeks — roughly 20% versus 14% — with more participants reaching the 15%, 20% and 25% thresholds. This is the trial behind Mounjaro's positioning as the most effective licensed option.
Across the SURMOUNT programme, tirzepatide also improved blood pressure, cholesterol and triglycerides, waist circumference and physical function scores, and in people with pre-diabetes substantially reduced progression to type 2 diabetes. In SURMOUNT-OSA, it significantly improved obstructive sleep apnoea severity — an indication now reflected in some markets.
Cross-trial figures are not head-to-head comparisons unless stated (SURMOUNT-5 is). Individual results vary; all results were achieved alongside diet and lifestyle change.
Each strength (2.5 mg to 15 mg) has its own pen, and one pen lasts a month.
Inject as soon as possible within 4 days (96 hours) of the missed dose. If more than 4 days have passed, skip it and take the next dose on your usual day. Never double up.
Escalation is guided by your response and tolerance — many patients maintain excellent results at 5 mg or 10 mg, and staying at a lower effective dose is good practice, not underachievement.
Progress Over Time
2.5 mg
Appetite reduction usually appears within days of the first dose. This starting dose is for tolerance-building, not maximum effect — modest early loss (often 2–3% of body weight) is normal and fine.
Dose steps up; weight loss becomes clearly visible on the scales and in clothes. Most patients settle into a pattern of steady weekly loss. Side effects, if any, cluster around each dose increase and then fade.
Typically the steepest part of the curve as you reach an effective maintenance dose. Trials show around 10–15% total loss in this window for many patients. This is when protein intake and resistance exercise matter most to protect muscle.
Loss continues more gradually, typically plateauing between months 12 and 18. A plateau is not failure — it's your body reaching a new set point. Your clinician may adjust dose or focus on maintenance.
Progress reviews are built into our service: we check weight, side effects and goals at each reorder, and dose changes are always clinician-approved.
FULL RANGE
Real medication. Real doctors. No inflated prices. Just results.
(oral semaglutide)
New for 2026. The UK's first once-daily GLP-1 weight loss tablet, MHRA-approved in June 2026. The same active ingredient as the Wegovy injection, with comparable weight loss in trials — no needles required.
(semaglutide)
Once-weekly injection with an average 15% weight loss over 68 weeks in the STEP 1 trial, plus proven cardiovascular benefits in people with heart disease. One of the most widely prescribed weight loss treatments worldwide. MHRA-licensed.
(orforglipron)
Eli Lilly's once-daily GLP-1 tablet, approved in the US in April 2026 and now licensed by the MHRA. It can be taken at any time of day, with or without food.
(Saxenda)
£— / month
Once-daily injection. Branded Saxenda has been discontinued by Novo Nordisk, but generic liraglutide (Nevolat) contains the same medicine at the same dose and remains available for patients established on liraglutide or those it suits clinically.
Price includes medication only, if prescribed. An active FromMars membership is required and billed separately. Membership does not include or guarantee a prescription; medication is not available without a membership.
Drug Interactions
Mounjaro can reduce pill absorption when starting and after each dose increase. Use additional barrier contraception for 4 weeks after starting and after each escalation, or switch to a non-oral method. This is specific to Mounjaro among the weight loss injections.
Combined with insulin or sulfonylureas, hypoglycaemia risk rises — doses of those medicines often need reducing. Coordinate with your diabetes team.
Slowed stomach emptying can alter absorption of drugs with a narrow therapeutic window (e.g. warfarin, levothyroxine) — inform your prescriber so monitoring can be arranged where relevant.
Not prohibited, but tolerance often drops and it adds empty calories; many patients naturally lose interest. Moderation strongly advised.
WARNINGS
Do not use if you are allergic to tirzepatide or any pen ingredient, pregnant, planning pregnancy imminently, or breastfeeding.
Not recommended with a history of pancreatitis, severe gastrointestinal disease (including gastroparesis), or alongside other GLP-1 medicines.
Used with caution — and sometimes not at all — in severe kidney or liver disease, diabetic retinopathy (in patients with diabetes), and in patients with a history of gallbladder disease.
Not appropriate for people with a history of eating disorders without specialist involvement — our consultation screens for this.
This is not an exhaustive list: the prescriber review exists precisely to catch what a checklist can't. Answer your consultation honestly — it's confidential, and it's how we keep you safe.
Lifestyle
Prioritise protein (roughly 1.2–1.6 g per kg of target body weight daily): rapid weight loss without adequate protein costs muscle as well as fat. Eggs, fish, poultry, dairy, legumes — protein first on the plate.
The single most effective way to keep the weight you lose being fat, not muscle. Bodyweight work counts.
Reduced appetite blunts thirst too. Aim for 2 litres daily — it also reduces nausea, constipation and headaches.
Your stomach empties slower; large or fatty meals are the most common trigger of nausea and reflux.
Eating too little causes fatigue, dizziness and nutrient gaps. If you're routinely under ~1,200 kcal, tell your clinician. A daily multivitamin is a sensible safeguard during rapid loss.
Store pens in the fridge at 2–8°C, in the original carton, away from the freezer compartment — never use a pen that has frozen. An in-use pen can be kept at room temperature (below 30°C) for up to 30 days.
Flying: carry pens in hand luggage (hold temperatures can drop below freezing) with a cool bag for long journeys; we can provide a travel letter for security. Every order ships in validated temperature-controlled packaging with a sharps bin available; delivery is free, next-day and unbranded.
Stopping & Maintenance
Obesity behaves as a long-term condition: when treatment stops, appetite signalling returns toward its old baseline, and in trial extensions patients who stopped tirzepatide regained a substantial share of lost weight within a year, while those who continued maintained or extended their loss.
That doesn't mean treatment is forever — it means stopping should be planned, not abrupt. Options we support include long-term maintenance at the lowest effective dose, a gradual clinician-guided taper with intensified lifestyle support, or switching to a different maintenance strategy.
Whatever the route, the habits built during treatment — protein, strength work, sleep, routine — are what carry the result.
Sources
Pricing
Mounjaro is priced per pen (one month of doses), with the price varying by strength — from [£X] for 2.5 mg up to [£X]. Displayed prices are the full cost, with no subscription lock-in.
READY TO START?
Complete a free online consultation and our UK prescribers will confirm whether Mounjaro is safe and appropriate for you, with medication dispensed by our GPhC-registered pharmacy and delivered free in temperature-controlled packaging.
