Weight Loss · Clinical Information
GLP-1 Weight Loss Medications
Pharmacist-reviewed information on Mounjaro and Wegovy, two NICE-approved weekly injectable treatments for supported weight management.
UK Pharmacist Reviewed
NICE Approved
GPhC Registered Pharmacy
Medication 01
Prescription Only
NICE Approved · TA1026
Mounjaro
tirzepatide
GIP + GLP-1Dual Agonist
What it is
Tirzepatide activates two hormones, GIP and GLP-1, that control hunger and blood sugar. This dual action makes it the most effective approved weight loss injection available.
How it works
Reduces appetite, slows digestion so you feel full longer, and helps your body manage blood sugar more effectively after meals.
Weight loss
Up to 20.9% average body weight loss over 72 weeks at the highest dose (SURMOUNT-1 trial).
Dosing
Once weekly injection. Dose increases every 4 weeks:
2.5 mg›
5 mg›
7.5 mg›
10 mg›
12.5 mg›
15 mg
Who it is for
Adults with a BMI of 30 or above, or BMI 27 or above with a weight-related condition such as high blood pressure, high cholesterol, or type 2 diabetes.
Side effects
- Nausea (most common, usually settles after a few weeks)
- Diarrhoea or constipation
- Reduced appetite and mild fatigue
- Injection site redness or irritation
Not suitable if
You have a personal or family history of medullary thyroid cancer or MEN-2, are pregnant or breastfeeding, or have a history of pancreatitis.
Medication 02
Prescription Only
NICE Approved · TA875
Wegovy
semaglutide
GLP-1Receptor Agonist
What it is
Semaglutide mimics GLP-1, a natural hormone released after eating that signals fullness to your brain. It has 94% structural similarity to the hormone your body already produces.
How it works
Suppresses appetite via hunger centres in the brain, slows stomach emptying so you stay fuller for longer, and has shown benefits for heart health in clinical trials.
Weight loss
Up to 14.9% average body weight loss over 68 weeks at the highest dose (STEP-1 trial). Also shown to reduce cardiovascular risk by 20% (SELECT trial).
Dosing
Once weekly injection. Dose increases every 4 weeks:
0.25 mg›
0.5 mg›
1 mg›
1.7 mg›
2.4 mg
Who it is for
Adults with a BMI of 35 or above, or BMI 30 or above with a weight-related condition such as high blood pressure, high cholesterol, or type 2 diabetes.
Side effects
- Nausea (most common, usually settles after a few weeks)
- Diarrhoea or constipation
- Headache and fatigue, particularly early on
- Injection site redness or irritation
Not suitable if
You have a personal or family history of medullary thyroid cancer or MEN-2, are pregnant or breastfeeding, or have a history of pancreatitis.
Side-by-Side Comparison
| Mounjaro (tirzepatide) | Wegovy (semaglutide) | |
|---|---|---|
| Drug class | GIP + GLP-1 Dual Agonist | GLP-1 Agonist |
| Average weight loss | Up to 20.9% | Up to 14.9% |
| Maximum dose | 15 mg per week | 2.4 mg per week |
| BMI eligibility | 30+ (27+ with condition) | 35+ (30+ with condition) |
| Injection frequency | Once weekly | Once weekly |
| Heart health benefit | Evidence ongoing | 20% MACE reduction |
| NICE approved | Yes — TA1026 | Yes — TA875 |
Clinical Disclaimer
This page is for informational purposes only and does not constitute medical advice. All prescriptions are issued following a clinical assessment by a UK-registered pharmacist prescriber. These medications are not suitable for everyone. Always read the patient information leaflet. If you experience serious side effects, call 111 or seek medical attention.
