Practical UK guide to using the Mounjaro KwikPen, including preparation, priming, injection technique, weekly timing, missed doses, storage, travel, and when to get medical advice.
4Fixed weekly doses per KwikPen
5sHold after pressing the button
2–8°CStorage for unused pens
Last updated: April 2026Source base: UK patient leaflet, KwikPen instructions for use, MHRA patient guidancePurpose: Educational guidance only
Mounjaro is a prescription-only medicine used once weekly by subcutaneous injection. The UK KwikPen is a multi-dose, single-patient-use pre-filled pen containing 4 fixed weekly doses. This guide is designed to make the practical steps clearer, but it does not replace the leaflet supplied with your pen or advice from your prescriber, pharmacist, or nurse.
✅ Before your first dose: read both the patient leaflet and the instructions for use in the pack. The KwikPen needs priming before injection, which is a step many summary guides miss.
What the KwikPen is and how it works
Single-patient use: do not share your pen with anyone else.
Multi-dose pen: one pen contains 4 fixed weekly doses.
Needles are not included: you need a compatible pen needle for each injection.
New needle each time: always use a fresh needle to reduce blocked needles and infection risk.
Dispose after 4 doses: do not try to extract leftover medicine.
⚠️ Do not improvise: if the pen looks damaged, the medicine looks cloudy or discoloured, the pen has been frozen, or the dose strength does not match your prescription, do not use it.
Step-by-step Mounjaro KwikPen injection guide
The sequence below follows the UK KwikPen workflow in plain English.
Wash your hands and inspect the pen
Wash your hands with soap and water.
Check the label and make sure the strength matches your prescription.
Check the expiry date.
Do not use the pen if it looks damaged, has been frozen, or the liquid contains particles, looks cloudy, or is discoloured.
Wipe the seal and attach a new needle
Pull the pen cap straight off.
Wipe the red inner seal with a swab.
Attach a new compatible pen needle and twist until it is secure.
Remove the outer needle shield and keep it.
Remove the inner needle shield and discard it.
Prime the pen
Turn the dose knob until the prime position appears.
Hold the pen with the needle pointing up.
Tap the cartridge holder gently so air bubbles rise.
Press the dose knob in until it stops, then slowly count to 5 while releasing a small amount of medicine into the air.
You should see a small amount of medicine at the tip. If not, repeat priming as directed in the instructions for use.
Choose your injection site
You can inject into the abdomen or thigh.
Another person can inject into the back of the upper arm.
If using the abdomen, stay at least 5 cm away from the belly button.
Rotate the site each week.
Dial the full dose and inject
Turn the dose knob until it stops and the full-dose icon is shown in the dose window.
Insert the needle into the skin.
Push the dose knob in until it stops.
Slowly count to 5 while holding the button before removing the needle.
Remove the needle and dispose safely
Pull the needle out of the skin. A small drop on the needle tip can be normal.
Carefully replace the outer needle shield.
Unscrew the used needle and discard it immediately in a sharps container.
Replace the pen cap.
Keep the pen steady, use a new needle every time, and hold for the full 5 seconds before removing it.
🚨 Common error: some people remove the pen too quickly or forget to prime it. Both can create avoidable problems. Prime first, then hold for the full 5-count during the actual injection.
Injection sites and site rotation
Where you can inject
Abdomen: often easiest for self-injection.
Thigh: another common self-injection site.
Upper arm: usually requires another person to help.
How to rotate sites properly
Change the injection site each week.
You can use the same general body area, but choose a different spot within that area.
Avoid skin that is bruised, sore, scarred, irritated, or infected.
ℹ️ If you also inject insulin: inject Mounjaro into a different site from your insulin injection.
Weekly timing and missed doses
Mounjaro is taken once weekly. You can inject at any time of day, with or without meals.
Choosing a weekly routine
Pick a day you can remember consistently.
Use a calendar, phone reminder, or app if needed.
You can change the day, but there should be at least 3 days between two doses.
Missed dose rule
If 4 days or less have passed: take the missed dose as soon as you remember.
If more than 4 days have passed: skip that dose and take the next one on your usual scheduled day.
Do not use a double dose to make up for a missed one.
⚠️ Restart after a break: if you have missed multiple weeks, do not guess your way back in. Contact your prescriber because restarting at a lower dose may be appropriate depending on the gap and your previous tolerability.
Dose strengths and dose changes
Mounjaro is available in 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg, and 15mg strengths. Dose changes are prescriber-led. Some people stay at a lower effective dose for longer; not everyone needs the highest strength.
ℹ️ Important: this page explains the licensed strengths and the practical use of the pen. It does not tell you what dose you personally should take or when you should increase.
Strength
Typical role
Practical note
2.5mg
Usual starting dose
Commonly used to begin treatment and build tolerability.
5mg
First increase
A common next step after the starting phase, depending on prescriber review.
7.5mg
Intermediate strength
May suit patients who need more effect but not higher strengths.
10mg
Higher mid-range strength
Used where clinically appropriate after lower-dose tolerance.
12.5mg
Advanced strength
Not needed by everyone.
15mg
Maximum licensed strength
The highest available strength, only where needed and tolerated.
Dose-specific guides
Use these pages for dose-specific pricing and practical context.
Starting dose
Mounjaro 2.5mg
Initial introduction strength
Usually the first dose used when beginning treatment.
After first use, the pen may be stored at room temperature up to 30°C.
Keep away from heat.
Dispose of the pen 30 days after first use or after the 4 weekly doses, whichever comes first.
Travel
Carry pens in hand luggage, not checked baggage.
Protect from heat and freezing.
Take prescription evidence if travelling by air.
⚠️ Storage rule: if the pen has been frozen, do not use it. If you think it has been overheated or damaged, ask your pharmacy before injecting.
Contraception, pregnancy, breastfeeding, and surgery
Pregnancy and breastfeeding
Do not use Mounjaro during pregnancy.
Do not use it while breastfeeding.
If you think you may be pregnant, speak to a healthcare professional straight away.
Trying to become pregnant
Mounjaro should be stopped at least 1 month before trying to become pregnant.
If you use the oral contraceptive pill
Add a barrier method such as condoms for 4 weeks after starting Mounjaro.
Also add barrier contraception for 4 weeks after each dose increase.
Another option is switching to a non-oral method such as the implant or coil after medical advice.
If you are having surgery or a procedure
Tell the healthcare team, including the anaesthetist, that you use Mounjaro.
Because it slows stomach emptying, procedure planning may need adjusting.
🚨 Do not guess with pregnancy or surgery timing: if either applies to you, get advice from your prescriber or treating team directly.
Practical ways to support safer use
Use the same weekly reminder system: calendar, app, or phone alarm.
Use a new needle every time.
Record the first-use date on the pen carton so the 30-day limit is easier to track.
Rotate injection sites to reduce local irritation.
Speak up early if side effects are interfering with eating, drinking, work, or daily life.
When to get medical advice urgently
Contact your prescriber promptly if you have:
vomiting that keeps recurring
poor fluid intake or signs of dehydration
persistent diarrhoea
worsening abdominal symptoms
problems using the pen or uncertainty about whether a dose was delivered
Seek urgent medical help if you have:
signs of a severe allergic reaction
severe, persistent stomach pain, especially if it may radiate to the back, with or without nausea and vomiting
collapse, severe confusion, or symptoms suggesting severe low blood sugar if you also use insulin or a sulphonylurea
any symptom that feels severe, sudden, or unsafe
🚨 Important safety point: acute pancreatitis is an uncommon but serious risk. Persistent severe stomach pain is not something to “wait out”.
Usage FAQs
Can I inject through clothing?
No. Inject into clean, dry, bare skin.
Do I need to prime every new needle?
Follow the instructions supplied with your pen. The UK KwikPen instructions include priming before injection to make sure the pen is working correctly.
Can I split one weekly dose into smaller doses?
No. Use Mounjaro exactly as prescribed. Do not split, double, or alter the dosing schedule yourself.
What if I am not sure the full dose went in?
Do not automatically inject again. Contact your supplying pharmacy or prescriber for advice.
Can I reuse the same needle?
No. Always use a new pen needle for each injection.
Used needles should go into a sharps container immediately after use.
Key takeaways
The KwikPen contains 4 fixed weekly doses.
Prime the pen before injection as directed in the instructions for use.
Use a new needle every time and hold for the full 5 seconds after pressing the button.
Missed doses have rules: do not double up.
Unused pens stay refrigerated at 2°C to 8°C; used pens can be kept at room temperature up to 30°C and should be discarded 30 days after first use.
If you use the pill, add barrier contraception for 4 weeks after starting and for 4 weeks after every dose increase.
Persistent severe stomach pain needs urgent medical attention.
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