Mounjaro (Tirzepatide) UK
Mounjaro is the first dual GIP/GLP-1 receptor agonist approved in the UK for chronic weight management. The SURMOUNT programme demonstrated average weight loss of up to 22.5% — the highest ever recorded in a phase 3 obesity trial.
UK prices from
£129.99
per month · live data
What is Mounjaro?
Tirzepatide · manufactured by Eli Lilly
Mounjaro (tirzepatide) is a once-weekly injectable medication manufactured by Eli Lilly and Company. It is the first approved dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist — a mechanism that sets it apart from earlier GLP-1 medications like semaglutide (Wegovy).
In the UK, the MHRA granted Mounjaro marketing authorisation for chronic weight management in November 2023, for adults with obesity (BMI ≥30) or overweight (BMI ≥27) with at least one weight-related health condition — such as hypertension, type 2 diabetes, dyslipidaemia, obstructive sleep apnoea, or cardiovascular disease. NICE subsequently recommended it for NHS use (Technology Appraisal TA961) in December 2023.
The SURMOUNT phase 3 clinical programme — comprising four large randomised controlled trials enrolling over 22,000 participants — represents the most comprehensive evidence base for any weight management medication to date. SURMOUNT-1, the pivotal trial in adults without diabetes (n=2,539), demonstrated average weight loss of 22.5% over 72 weeks at the 15mg dose versus 2.4% for placebo.
How does Mounjaro work?
Dual GIP and GLP-1 receptor activation
Tirzepatide is a single synthetic peptide engineered to activate both GIP and GLP-1 receptors with high affinity. GIP receptors are expressed in adipose tissue, bone, and the brain; GLP-1 receptors in the gut, pancreas, and brainstem. Activating both pathways simultaneously produces synergistic effects on appetite suppression and energy metabolism — which is why tirzepatide outperforms semaglutide in head-to-head trials.
Appetite suppression and reduced calorie intake
Both receptors modulate hunger and satiety signals in the hypothalamus. In clinical trials, tirzepatide significantly reduced daily energy intake — in some participants by over 500kcal per day. It also reduces cravings, particularly for high-fat and high-calorie foods.
Slowed gastric emptying
Mounjaro slows the movement of food from the stomach to the small intestine, which extends the post-meal feeling of fullness, moderates post-prandial glucose rises, and reduces overall caloric absorption throughout the day.
Improved insulin sensitivity and metabolic health
By stimulating insulin secretion in a glucose-dependent manner and suppressing glucagon, tirzepatide improves blood sugar control and insulin sensitivity in peripheral tissues. This produces meaningful metabolic and cardiovascular benefits — including improvements in blood pressure, lipids, and markers of liver health — that extend well beyond weight reduction alone.
Mounjaro dose escalation schedule and UK prices
Mounjaro uses a mandatory step-up dosing regimen designed to minimise gastrointestinal side effects. Each dose is maintained for a minimum of four weeks before escalation. The 2.5mg starting dose is not a therapeutic dose — it exists solely to improve tolerability. Your prescribing clinician will guide your individual schedule based on your response and tolerability.
Mounjaro 2.5mg
Weeks 1–4Starting dose only — not a therapeutic dose. Used to help your body adjust and minimise side effects.
from £129.99 · avg £161 · up to £229
Mounjaro 5mg
Weeks 5–8First therapeutic dose. Most patients begin noticing appetite changes here.
from £159.99 · avg £176 · up to £193.94
Mounjaro 7.5mg
Weeks 9–12Increased to improve efficacy. Many patients achieve their goals at this dose and remain here long-term.
from £134.95 · avg £166 · up to £267.97
Mounjaro 10mg
Weeks 13–16Further escalation if tolerated and additional weight loss is needed.
from £179 · avg £255 · up to £302.97
Mounjaro 12.5mg
Weeks 17–20Penultimate maintenance dose for patients requiring further dose escalation.
from £179 · avg £274 · up to £314.97
Mounjaro 15mg
Week 21+Maximum approved maintenance dose. Used when lower doses do not produce sufficient effect.
from £179 · avg £292 · up to £334.97
Clinical trial evidence — the SURMOUNT programme
SURMOUNT-1
Jastreboff et al., NEJM, 20222,539 adults with obesity or overweight without diabetes
22.5% average weight loss at 15mg over 72 weeks. 57% of participants lost ≥20% of body weight.
SURMOUNT-2
Garvey et al., Lancet, 2023938 adults with obesity and type 2 diabetes
15.7% average weight loss at 15mg over 72 weeks, plus significant HbA1c reduction.
SURMOUNT-4 (withdrawal study)
Aronne et al., JAMA, 2024783 adults following 36-week open-label run-in phase
Participants who switched to placebo regained ~14% of body weight, confirming continued treatment is needed to maintain results.
SURMOUNT-5 (vs Wegovy)
Wilding et al., NEJM, 2025Head-to-head versus semaglutide 2.4mg in adults with obesity
Tirzepatide produced 20.2% vs 13.7% average weight loss — a 47% greater relative reduction than semaglutide.
Who is Mounjaro suitable for in the UK?
The MHRA-approved indication for Mounjaro in weight management specifies the following criteria. All prescribing must be performed by a registered UK healthcare professional who confirms your clinical suitability.
This reflects key criteria from the MHRA-approved SmPC and is not an exhaustive list of contraindications or cautions. Eligibility must always be confirmed by a qualified prescriber.
How to use the Mounjaro KwikPen
Mounjaro is supplied as a single-dose pre-filled auto-injector pen (KwikPen). Each pen delivers one dose and is then disposed of in a sharps bin. Your prescribing pharmacist or clinician must provide injection training before you begin treatment.
How to inject Mounjaro — step by step
Select your injection site: abdomen (at least 5cm from your navel), upper outer thigh, or outer upper arm.
Clean the site with an alcohol wipe and allow to fully dry.
Remove the pen cap. Do not touch the needle end.
Press the pen firmly against clean, dry skin. Press and hold the unlock button until you hear the first click (injection starts).
Continue holding the pen against your skin. When you hear a second click, the injection is complete.
Keep the pen pressed against your skin for at least 10 seconds after the second click to ensure the full dose is delivered.
Discard the used pen immediately in a sharps container.
Rotate your injection site each week to reduce the risk of skin reactions or lipohypertrophy.
Storage: Keep unopened pens refrigerated (2–8°C). Once removed from the fridge, pens can be kept at room temperature (up to 30°C) for up to 21 days. Never freeze. Protect from direct sunlight and heat.
Timing: Take your injection on the same day each week. If you want to change your injection day, make sure at least 3 days have passed since your last dose.
Mounjaro on the NHS vs private prescriptions in the UK
NICE approved Mounjaro for NHS use in England (TA961) in December 2023, recommending it for adults who meet the eligibility criteria as part of a specialist weight management service. Access is being rolled out in phases — initially through NHS tier 3 specialist weight management services, with planned expansion over the following years.
NHS eligibility is assessed by specialist clinicians and currently prioritises those with the highest clinical need. The NHS list price for Mounjaro is substantially lower than private market prices.
For those who cannot yet access Mounjaro through the NHS, a private prescription from a GPhC-registered UK online pharmacy or clinic is the most common route. Private prices vary considerably between providers — by as much as £100 or more per month for the same dose. Comparing providers before committing to a service is important.
Frequently asked questions about Mounjaro
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Medical disclaimer
Mounjaro (tirzepatide) is a prescription-only medicine (POM) in the UK. It can only be legally supplied following a clinical assessment by a registered healthcare professional. This page provides general educational information only and does not constitute or replace individual medical advice. Clinical information is based on the MHRA-approved Mounjaro SmPC and published peer-reviewed clinical trial data. Always consult your GP or a registered prescriber before starting, changing, or stopping any prescription medication.
Quick reference
Active ingredient
Tirzepatide
Drug class
Dual GIP/GLP-1 agonist
Manufacturer
Eli Lilly
How taken
Once-weekly injection
MHRA approved (obesity)
November 2023
NICE approved (NHS)
December 2023 (TA961)
Dose range
2.5mg to 15mg
Starting dose
2.5mg (4 weeks)
Maintenance dose
5mg to 15mg
Trial weight loss
Up to 22.5%
Pen type
KwikPen auto-injector
Max weight loss
22.5%
SURMOUNT-1 (72 weeks)
vs Wegovy
+47%
Greater relative reduction
Doses
6
2.5mg to 15mg weekly
Frequency
Weekly
Same day each week
Side effects
Most common — particularly when increasing dose:
- Nausea (affects ~30% of users)
- Diarrhoea
- Vomiting
- Constipation
- Abdominal pain or discomfort
- Decreased appetite
- Injection site reactions
- Fatigue (especially at dose changes)
- Dyspepsia (indigestion)
- Dizziness
Side effects are typically mild to moderate and most pronounced during dose escalation. Eating smaller portions, avoiding fatty foods, and staying well hydrated can help manage nausea.
Compare Mounjaro prices now
Prices vary by £100+ per month between providers for the same dose. See live prices from every GPhC-registered UK pharmacy in one place.
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About this page
Written and reviewed by the GLP-1 Compare editorial team. Clinical information is based on the MHRA-approved Mounjaro SmPC, SURMOUNT phase 3 trial publications, and NICE TA961. Last reviewed February 2026.