Mounjaro, explained in plain English.
Independent UK information on tirzepatide. What it does, who can have it, how the side effects feel, when to get help, and what every pharmacy charges.
One medicine, from first pen to maintenance.
Written from the NHS, the MHRA, NICE and the Mounjaro product information. Every page lists its sources and shows the day it was reviewed.
New to Mounjaro, or about to start? These five pages cover what most people need before the first injection.
- The Mounjaro safety guideWho should not take it, the serious warnings, missed doses, storage and how to spot a fake pen.
- When to contact your Mounjaro prescriber, 111 or 999Call 999 for a swollen throat, trouble breathing or severe tummy pain into your back. Call 111 if fluids will not stay down. Raise mild side effects at review.
- What is Mounjaro? How tirzepatide works for weight lossMounjaro is tirzepatide, a once-weekly injection licensed in the UK for type 2 diabetes and weight management. How it works, who it suits and trial results.
- Mounjaro dose steps explained: 2.5mg to 15mg titrationMounjaro comes in six doses from 2.5mg to 15mg. You start on 2.5mg for 4 weeks, then rise in 2.5mg steps with at least 4 weeks on each. When to stay or move up.
- How to buy Mounjaro in the UK safely: the full processMounjaro is prescription only. How a safe UK purchase works, from the consultation, ID and weight checks to delivery, plus the red flags of a fake seller.
Safety before price.
A cheaper pen helps nobody if the seller is not a pharmacy or the medicine does not suit you. Every page on this site follows the same order.
How this site worksPrimary sources only
Clinical facts come from the NHS, the MHRA, NICE, the Mounjaro summary of product characteristics and peer-reviewed trials. No pharmacy or company is ever cited for a clinical claim.
No codes on price pages
Mounjaro is a prescription-only medicine. The price pages list what pharmacies charge, with a link to each pharmacy's GPhC register entry and to its page on Monj, so you can check a pharmacy before you buy.
Three levels of help
Every side effect page ends with the same plain guide: when to call 999, when to call 111 or see a GP today, and what can wait for your next check.
Dated and reviewed
Each page shows the day it was reviewed and each price page shows the day prices were checked. When the facts change, the date changes with them.
From 2.5mg to 15mg.
Six doses, one KwikPen a month, at least 4 weeks on each step. Choose a dose to see where it sits and what the cheapest pen costs today.
The starting dose
Four weekly injections to let your body adjust before the first increase. Appetite often drops, and nausea is most common in these early weeks.
How the dose steps work- Average
- £138.05
- Highest
- £229.00
- Per week
- £22.00
The first treatment dose
Reached after 4 weeks on 2.5mg. Some people stay here for months. Side effects often return briefly for a week or two after the step up.
How the dose steps work- Average
- £163.46
- Highest
- £244.00
- Per week
- £30.00
A common holding dose
Week 9 at the earliest. Prescribers often hold people here while weight loss is steady and side effects are under control.
How the dose steps work- Average
- £215.41
- Highest
- £294.00
- Per week
- £42.00
A long-term dose for many
Week 13 at the earliest. In the SURMOUNT-1 trial, people on 10mg lost about 19.5 per cent of body weight over 72 weeks on average.
How the dose steps work- Average
- £242.46
- Highest
- £324.00
- Per week
- £47.00
When progress slows
Week 17 at the earliest. Used when weight loss has slowed on 10mg and the lower doses suited you.
How the dose steps work- Average
- £260.74
- Highest
- £344.00
- Per week
- £50.50
The highest licensed dose
Week 21 at the earliest. Not everyone needs it. The gap between the cheapest and dearest pharmacy is widest here.
How the dose steps work- Average
- £278.06
- Highest
- £359.00
- Per week
- £54.75
Side effects, by body system.
Most side effects are mild and fade within weeks. A few need urgent care. Each page tells you which is which.
Start here
- When to contact your Mounjaro prescriber, 111 or 999
- How long do Mounjaro side effects last
- Mounjaro sick day rules
Injection and everyday
- How to use the Mounjaro KwikPen
- Mounjaro injection site reactions
- Mounjaro before surgery and anaesthesia
- Mounjaro and the contraceptive pill
- Mounjaro and pregnancy
- Mounjaro in hot weather
- Norovirus and Mounjaro
Stomach and digestion
- Mounjaro nausea and vomiting
- Mounjaro stomach pain
- Mounjaro constipation
- Mounjaro diarrhoea
- Mounjaro sulphur burps, bloating and acid reflux
- Mounjaro and gastroparesis
Urgent warning signs
- Mounjaro and pancreatitis
- Mounjaro, gallstones and your gallbladder
- Mounjaro and cholecystitis
- Mounjaro and bowel obstruction (ileus)
- Mounjaro allergic reaction
- Mounjaro, your kidneys and dehydration
Energy, heart and blood sugar
- Mounjaro fatigue
- Mounjaro dizziness and low blood pressure
- Mounjaro and a fast pulse
- Mounjaro headaches
- Mounjaro and low blood sugar (hypoglycaemia)
- Mounjaro and diabetic eye changes
- Feeling cold on Mounjaro
Skin, hair and body
- Mounjaro hair loss
- Mounjaro face and loose skin
- Mounjaro itching, rash and hives
- Mounjaro skin pain and sensitivity
- Mounjaro muscle loss
- Mounjaro and periods
Guides people read first.
45 guides in all, from NHS eligibility to travelling with a pen.
When to get help.
The same three levels sit at the end of every side effect page. If you are unsure which applies, call 111.
Call 999 or go to A&E
Severe stomach pain which does not ease and may spread to your back, repeated vomiting, swelling of the face, lips or throat, trouble breathing, or a swollen painful belly with no wind or stools.
Call 111 or see a GP today
Vomiting or diarrhoea for more than 24 hours, little or no urine, fainting, a pounding heartbeat with dizziness, a spreading rash, pain under the right ribs after eating, or low blood sugar if you take insulin or a sulfonylurea.
Mention at your next check
Mild nausea, burps, constipation, tiredness, hair shedding, feeling cold, taste changes, or injection site redness which settles within a few days.
Check the price before you pay.
The same Mounjaro 2.5mg pen costs from £88.00 to £229.00 today, delivery included. 79 pharmacies, six doses, one page.
See every Mounjaro price