Mounjaro (Tirzepatide) — UK Guide

The dual-action GLP-1 treatment showing the highest weight loss in clinical trials. How it works, what it costs, and how to access it in the UK.

Regulatory status: Mounjaro is MHRA-approved in the UK for type 2 diabetes. Its use for weight management is off-label — widely prescribed by CQC-registered clinics based on strong clinical evidence, but not yet NICE-approved for this indication. Learn more about access pathways.

What Is Mounjaro?

Drug class

Dual GIP/GLP-1 agonist

Active ingredient

Tirzepatide

NICE approved (weight loss)

Under review

Mounjaro is the brand name for tirzepatide, manufactured by Eli Lilly. It's a "dual agonist" — meaning it activates two hormone receptors instead of one. While treatments like Wegovy target only GLP-1, Mounjaro targets both GLP-1 and GIP (glucose-dependent insulinotropic polypeptide).

GIP is a second gut hormone involved in appetite regulation and energy metabolism. By targeting both pathways simultaneously, tirzepatide appears to produce greater appetite suppression and higher average weight loss than GLP-1-only treatments.

Mounjaro was approved by the MHRA in 2023 for type 2 diabetes. While a separate weight management indication has been approved in the US (as Zepbound), the UK NICE appraisal for weight management is still pending. In the meantime, UK prescribers can and do prescribe it off-label for weight loss based on the SURMOUNT clinical trial evidence.

Dose Escalation Schedule

Mounjaro uses a gradual dose escalation with 6 dose levels. You start at the lowest dose and increase every 4 weeks. Your prescriber will determine the appropriate maintenance dose based on your response and tolerability.

Phase Weeks Dose Notes
Escalation 1 Weeks 1–4 2.5mg Starting dose — not a therapeutic dose, designed for tolerability
Escalation 2 Weeks 5–8 5mg First therapeutic dose — weight loss effects begin
Escalation 3 Weeks 9–12 7.5mg Some patients may stay at this dose if response is good
Escalation 4 Weeks 13–16 10mg Mid-range dose — good balance of efficacy and tolerability
Escalation 5 Weeks 17–20 12.5mg Higher dose for additional weight loss
Maximum Week 21 onwards 15mg Highest dose — produced the strongest results in trials

Important: Not everyone needs to reach 15mg. Your prescriber will find the dose that works for you with acceptable side effects. Many people achieve significant weight loss at 10mg or 12.5mg. Never adjust your dose without consulting your prescriber.

Effectiveness: SURMOUNT Trial Results

Mounjaro's effectiveness for weight loss was demonstrated in the SURMOUNT programme — a series of phase 3 clinical trials involving over 5,000 participants without type 2 diabetes.

SURMOUNT-1 Key Findings (72 weeks)

5mg dose

15.0%

Average weight loss

10mg dose

19.5%

Average weight loss

15mg dose

20.9%

Average weight loss

At the highest dose (15mg):

  • 96% achieved at least 5% weight loss
  • 83.5% achieved at least 15% weight loss
  • 56.7% achieved at least 20% weight loss

Source: Jastreboff et al., NEJM 2022; 387:205-216. DOI: 10.1056/NEJMoa2206038

What does this mean in practice?

For someone weighing 100kg (15st 10lb), a 20.9% weight loss would mean losing approximately 21kg (3st 4lb) over 72 weeks at the highest dose. At 10mg, the average loss would be around 19.5kg. Individual results vary significantly based on starting weight, diet, exercise, and adherence.

Important: Clinical trial results are averages across study populations. Individual results vary significantly. These are not guaranteed outcomes. Placebo group lost 3.1% (lifestyle changes alone also produce results).

Side Effects

Mounjaro shares a similar side effect profile to other GLP-1 treatments. Most side effects are gastrointestinal and typically improve with time.

Common (more than 1 in 10 people)

  • Nausea (most common, usually worst during dose increases)
  • Diarrhoea
  • Constipation
  • Vomiting
  • Decreased appetite
  • Abdominal pain
  • Injection site reactions

Serious but rare

  • Pancreatitis
  • Gallbladder problems (gallstones)
  • Kidney problems (usually from dehydration)
  • Allergic reactions
  • Changes in heart rate

For detailed information on managing side effects and when to seek help, see our complete side effects guide.

Mounjaro Costs by Clinic and Dose

Prices shown are monthly costs from public clinic websites. All include an online consultation with a prescriber.

Clinic CQC 2.5mg 5mg 7.5mg 10mg 12.5mg 15mg
Boots Online Doctor Not yet inspected GBP 176.97 — — — — GBP 334.97
LloydsPharmacy Online Doctor Good GBP 190.00 GBP 215.00 GBP 260.00 GBP 300.00 GBP 315.00 GBP 325.00
Superdrug Online Doctor Good GBP 195.00 GBP 245.00 GBP 295.00 GBP 335.00 GBP 345.00 GBP 370.00
Juniper Not yet inspected GBP 199.00 GBP 229.00 GBP 279.00 GBP 304.00 GBP 329.00 GBP 339.00
Numan Good GBP 229.00 GBP 239.00 GBP 289.00 GBP 309.00 GBP 329.00 GBP 339.00

Pricing from public clinic websites, March 2026. Costs may vary. All clinics are CQC-registered. See our cost calculator for detailed comparisons.

How to Get Mounjaro for Weight Loss

Private clinic pathway (only current option for weight loss)

  1. Choose a CQC-registered online clinic offering Mounjaro
  2. Complete an online health questionnaire
  3. A GMC-registered prescriber reviews your profile and medical history
  4. If clinically appropriate, Mounjaro is prescribed off-label for weight management
  5. Medication dispensed by a GPhC-regulated pharmacy and delivered to your door

Most clinics offer same-day assessment with delivery in 2-3 working days.

Why not on the NHS?

Mounjaro is not yet NICE-approved for weight management. NICE has appraised tirzepatide for type 2 diabetes but has not completed its assessment for obesity. Until this happens, NHS specialist weight management services cannot prescribe it for weight loss. The only NHS-approved GLP-1 for weight management is Wegovy.

For a detailed comparison of NHS and private pathways, see NHS vs Private. For BMI eligibility criteria, see our eligibility checker.

Frequently Asked Questions

Is Mounjaro approved for weight loss in the UK?
Mounjaro (tirzepatide) is MHRA-approved for type 2 diabetes in the UK. Its use for weight management is off-label — meaning prescribers can legally prescribe it based on clinical evidence, but it is not yet NICE-approved specifically for weight loss. NICE appraisal for the weight management indication is expected. CQC-registered clinics widely prescribe it based on the SURMOUNT trial evidence.
How is Mounjaro different from Wegovy?
Mounjaro (tirzepatide) is a dual GIP/GLP-1 receptor agonist, targeting two gut hormones rather than one. Wegovy (semaglutide) targets only GLP-1. In clinical trials, Mounjaro showed higher average weight loss (15-21% vs 12-15%), though head-to-head comparisons are limited. Mounjaro is not yet NICE-approved for weight loss, while Wegovy is.
Can I get Mounjaro on the NHS?
Not currently for weight management. Mounjaro is only NICE-approved for type 2 diabetes. NICE has not yet appraised tirzepatide for weight management, so it's not available through NHS weight management services. It's currently only available for weight loss through private clinics.
How much weight can I lose on Mounjaro?
In the SURMOUNT-1 trial, participants on the highest dose (15mg) lost an average of 20.9% of body weight over 72 weeks. Lower doses showed 15-19.5% average loss. Individual results vary significantly. Your prescriber will monitor progress and adjust your plan accordingly.
Is Mounjaro safe for weight loss if it's prescribed off-label?
Off-label prescribing is a common, legal, and regulated practice in UK medicine. CQC-registered clinics prescribe Mounjaro for weight loss based on strong clinical trial evidence (SURMOUNT programme). The prescriber takes full clinical responsibility and must be satisfied the treatment is appropriate for each individual patient.

Compare Mounjaro Prices

All clinics on SlimmingBoost are CQC-registered and use GPhC-regulated pharmacies.

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Sources

  • Jastreboff AM et al. "Tirzepatide Once Weekly for the Treatment of Obesity." NEJM 2022; 387:205-216. DOI: 10.1056/NEJMoa2206038
  • MHRA Summary of Product Characteristics — Mounjaro (tirzepatide)
  • NICE Technology Appraisal TA924: Tirzepatide for type 2 diabetes (2023)
  • General Medical Council — Prescribing unlicensed medicines (off-label guidance)
  • Clinic pricing from public provider websites, verified March 2026