If you’ve been prescribed Mounjaro (tirzepatide) for type 2 diabetes or weight management, you might feel nervous about injecting it yourself. That’s completely normal. Most people feel confident by their third or fourth injection.
This guide walks you through the process safely, from checking your pen to disposing of it properly, with tips from our NHS-accredited pharmacists at Pharmacy M. This guide follows current UK prescribing guidance from the NHS and manufacturer instructions for Mounjaro.
What is Mounjaro?
Mounjaro is a once-weekly injection for type 2 diabetes and weight management. Its active ingredient, tirzepatide, mimics two hormones that regulate blood sugar and reduce appetite. You can read more about how Mounjaro works in your body in our dedicated guide.
You inject it under the skin using a pre-filled pen. Most people describe the sensation as a small pinch. Typical starting doses are 2.5mg weekly, increasing gradually based on how you respond.
Not yet prescribed Mounjaro? Our pharmacist prescribers can assess your suitability with no GP referral needed.
Before You Start: 5 Safety Checks
[INFOGRAPHIC 1: “Your 5-Step Pre-Injection Checklist” — vertical checklist card with tick boxes, icons, and Pharmacy M brand colours.]
- Check the expiry date printed on the label.
- Inspect the liquid. It should be clear and colourless. Discard if cloudy or discoloured.
- Confirm the dose matches your prescription. Pens come in different strengths.
- Check storage. Discard if the pen has been frozen or left in direct sunlight.
- Review the injection site. Avoid cuts, bruises, scars, or hard lumps.
If you’re unsure about anything, call us or speak to your prescriber before injecting.
What You’ll Need
- One Mounjaro pen at the correct dose
- An alcohol wipe or cotton pad
- A sharps bin
- Clean, washed hands
Sharps bins are legally required for disposal. Don’t put used pens in household rubbish. We provide sharps bins and accept them for disposal at Pharmacy M when you collect your prescription.
How to Inject Mounjaro: Step by Step
Step 1: Prepare Your Injection Site
Choose one of three sites: abdomen, thigh, or back of the upper arm. The abdomen is easiest for most people. Stay at least 5cm from your belly button.
Rotate your site each week to prevent skin thickening (lipohypertrophy). Clean the area with an alcohol wipe and let it dry for 10 to 15 seconds before injecting.
Step 2: Check the Pen
Take the pen out of the fridge 30 minutes before injecting. Cold medication stings more. Remove the base cap by pulling straight (don’t twist). Check the dose window matches your prescription and confirm the injection button is grey, not green. A green button means the pen has already been used.
Step 3: Inject
Pinch a fold of skin at the injection site and place the pen flat against it at a 90-degree angle. Press the button firmly until you hear a click, then hold the pen in place for a full 10 seconds. Count slowly. Pulling away early means you won’t get the complete dose.
After 10 seconds, the button should turn green. That’s your confirmation the injection is done. Lift the pen straight off without twisting. A small drop of blood is normal.
Didn’t hear the click? The click can be quiet. The green indicator is what matters. If the button hasn’t turned green after 10 seconds, contact your pharmacist as the dose may not have been delivered.
Step 4: Dispose of the Pen
Drop the used pen straight into your sharps bin without recapping it. Note the date and site used. When the bin is three-quarters full, seal and return it to us, your GP surgery, or a local council facility.
How to Store Mounjaro Pens?
Store unopened pens in the fridge at 2 to 8°C. Never freeze them. Keep in the original carton away from light and freezer compartments. After first use, store at room temperature (up to 30°C) or in the fridge for up to 21 days. Write the start date on the carton.
When travelling, use an insulated bag and keep pens in your hand luggage as cargo hold temperatures can damage the medication.
Side Effects of Mounjaro and When to Get Help
Common early side effects include nausea, diarrhoea or constipation, reduced appetite, stomach discomfort, and tiredness. These usually ease as your body adjusts. Smaller meals and lower-fat foods help with nausea.
Seek medical help immediately for: severe or persistent stomach pain, persistent vomiting, signs of pancreatitis (upper stomach pain spreading to the back), gallbladder problems (pain, fever, yellowing of skin), difficulty breathing, or swelling of the face or throat.
If you take Mounjaro alongside other diabetes medications, watch for low blood sugar. Symptoms include shakiness, sweating, dizziness, and confusion. Keep glucose tablets or a sugary drink to hand.
Not sure if what you’re experiencing is normal? Our pharmacists can help through our NHS Pharmacy First service with no GP appointment needed.
Conclusion
Taking control of your own treatment takes courage, and asking questions is part of doing it well. If something in this guide has left you unsure, or you simply want a pharmacist to show you the technique face to face before your first dose, please don’t hesitate to reach out.
At Pharmacy M, we support patients at every stage of their Mounjaro journey, from first prescription to ongoing treatment.
Collect your prescription with us, bring in your sharps bin, or book a consultation at a time that suits you. We’re here Monday through Sunday, and we’d rather you asked than worried.
FAQs
What if I miss a dose?
Inject as soon as you remember if your next dose is more than 3 days away, otherwise skip it and continue on your regular day.
Does the time of day matter?
No, just pick a consistent day each week. Fasting during Ramadan? See our guide on timing your Mounjaro injection around fasting.
Can I inject near the same area as insulin?
Yes, but always use a different spot and never the exact same location on the same day.
Can I take Mounjaro while pregnant or breastfeeding?
No. Stop at least 2 months before trying to conceive and contact your doctor immediately if you become pregnant.
What if I accidentally inject twice in one week?
Call your doctor immediately and don’t wait for symptoms to appear.
