How do you inject Mounjaro? A step-by-step guide
Published 5 May 2026 · Updated 7 July 2026
Learning how to inject Mounjaro takes about ten minutes, and after the first few weeks it becomes a two-minute routine. The injection goes under the skin of the stomach or thigh once a week: attach a new pen needle, prime the KwikPen, dial the dose, insert the needle and hold the dose knob down for a slow count of five.
Your first injection should not come from a written guide alone. Ask the doctor or pharmacist managing your treatment to demonstrate the technique before you inject on your own; a five-minute demonstration prevents most of the errors this article covers.
Below is the full routine from the official instructions for use: preparing the pen, choosing and rotating sites, the injection itself, and what to do with the needle afterwards.
What do you need before your first injection?
Four things: the Mounjaro KwikPen in your dose strength, a new pen needle, an alcohol swab, and a sharps container. Gauze or a cotton ball is useful for afterwards.
Needles are not included in the pen box. The KwikPen takes standard screw-on pen needles, sold separately at pharmacies including Dischem and Clicks; most people use short 4 mm or 5 mm needles. Ask your pharmacist which needle to use, and buy a full month's supply, because every injection needs a fresh one.
Check the pen before each use. The liquid should be colourless to slightly yellow. Do not use a pen that is cloudy, contains particles, has been frozen, is past its expiry date, or does not match the strength on your treatment plan.
One pen holds four fixed weekly doses of a single strength. Which strength you are on, and when it changes, is set by your doctor; the schedule is explained in our Mounjaro dosage guide.
Where do you inject Mounjaro?
Mounjaro is injected subcutaneously, into the fatty layer just under the skin, not into muscle or a vein. The registered sites are the stomach and the front of the thigh if you inject yourself, and the back of the upper arm if someone else gives the injection.
| Site | Who can inject | Notes |
|---|---|---|
| Stomach (abdomen) | You or someone else | Stay at least 5 cm away from the belly button |
| Front of thigh | You or someone else | Upper outer part, easy to reach seated |
| Back of upper arm | Someone else | Hard to reach properly on yourself |
Rotate your site every week. You can stay in the same body area, but pick a spot a few centimetres from last week's. Rotation prevents lumps, bruising and irritated skin, and it helps the medicine absorb consistently.
Avoid skin that is bruised, scarred, hard, or tender, and never inject through clothing.
How do you inject Mounjaro step by step?
These steps follow the official KwikPen instructions for use.
- Wash your hands with soap and water.
- Pull the pen cap straight off and check the medicine and expiry date.
- Wipe the red inner seal at the top of the cartridge with an alcohol swab.
- Push a new capped needle straight onto the pen and twist until tight. Pull off the outer needle shield and keep it; pull off the inner shield and discard it.
- Prime the pen: turn the dose knob until you hear 2 clicks and the extended line appears in the dose window. Hold the pen needle-up, tap the cartridge holder gently so air bubbles rise, then push the dose knob in until it stops and slowly count to 5. A drop of medicine at the needle tip means the pen is primed. No drop? Repeat the priming steps, up to two more times, then try a new needle.
- Dial the dose: turn the dose knob until it stops and the 1 appears in the window. That is one full weekly dose of 0.6 ml.
- Insert the needle fully into your chosen site, then push the dose knob in until it stops and slowly count to 5 while holding it down.
- Check that the window shows 0 before pulling the needle out. The 0 confirms you received the full dose. If it does not show 0, put the needle back into your skin and finish the push; do not redial.
A small drop of medicine on the needle tip after you withdraw is normal and does not affect your dose.
The same core technique applies across this class of medicine; if you ever switch products, see how to inject GLP-1 medication for the general version.
What do you do after the injection?
If you see a spot of blood, press lightly with gauze or a cotton ball. Do not rub the site; rubbing pushes medicine around and can cause bruising.
Then deal with the needle immediately. Replace the outer needle shield carefully, unscrew the capped needle, and drop it into your sharps container. Never store the pen with a needle attached: it can leak, block the needle, and let air into the cartridge.
Put the pen cap back on and store the pen. After four doses the pen is finished and should be disposed of, even if you can see a little liquid left inside.
Mild redness, itching or a small bump at the injection site is common and normally fades within a day or two. A site that becomes increasingly painful, hot or swollen is not normal: contact your doctor.
How do you store the Mounjaro KwikPen?
Unused pens live in the fridge at 2 to 8 degrees Celsius. Do not freeze a pen; a pen that has frozen must be thrown away even after it thaws.
Once you have used a pen for the first time, you may keep it out of the fridge at room temperature up to 30 degrees Celsius. From that first use it lasts 30 days, which comfortably covers its four weekly doses. Keep it away from heat and direct sun, cap on, out of reach of children.
For travel, a cooler bag handles long trips, and an unused pen should go back into a fridge at your destination. In a South African summer, do not leave the pen in a parked car; cabin temperatures climb well past 30 degrees.
Injecting straight from the fridge is safe, though many people find the injection more comfortable if the pen sits at room temperature for 20 to 30 minutes first.
How do you dispose of needles in South Africa?
Used pen needles go into a sharps container immediately after each injection, never loose into household rubbish. Loose needles put cleaners, waste collectors and children at risk of needlestick injuries.
Pharmacies sell small sharps containers for home use, and many, including major groups, accept full containers back for safe medical-waste disposal. Some clinics and GP practices take them too. Phone ahead to confirm your branch participates.
If you cannot get a purpose-made container straight away, the leaflet allows a rigid household container with a secure lid, such as a thick plastic bottle, clearly marked, kept away from children, and never recycled. Swap to a proper sharps container as soon as you can.
Used pens themselves should also be disposed of as your pharmacist advises rather than binned with the needle still attached.
Does the Mounjaro injection hurt?
Very little, usually. Pen needles are short and thin, and most people describe the injection as a brief pinprick or nothing at all. Letting the pen warm up, relaxing the muscle under the site and injecting smoothly all help.
Injection-site reactions such as redness or itching affect a minority of users and are usually mild. The medicine's common side effects are digestive rather than skin-related: nausea, diarrhoea, constipation and vomiting, mostly around dose increases. Mounjaro is not suitable in pregnancy or while breastfeeding, or for people with a personal or family history of medullary thyroid cancer or MEN2 syndrome; the full picture is in our guide to Mounjaro side effects.
Severe, persistent stomach pain, with or without vomiting, can signal pancreatitis: seek medical care immediately.
If injections make you anxious, say so at your assessment. A doctor or nurse can watch your technique, correct small errors and settle nerves quickly; that support is part of structured follow-up, described on our what to expect page.
Frequently asked questions
What time of day should you inject Mounjaro?
Any time, with or without food. Consistency of the day matters more than the hour; pick a weekly slot you will remember.
Do you pinch the skin when injecting Mounjaro?
Usually not. Short pen needles are designed to reach the fat layer without a skin fold, but very lean people are sometimes shown a pinch-up technique. Ask the professional who demonstrates your first dose.
Can you reuse a needle on the Mounjaro pen?
No. Use a new needle for every injection. Reused needles blunt quickly, hurt more, can block, and raise the risk of infection.
Can other people use my Mounjaro pen?
No, never. The pen is a single-patient device; sharing it can transmit serious infections even with a fresh needle.
What if there are air bubbles in the pen?
Small bubbles are normal and are cleared by priming. Hold the pen needle-up, tap the cartridge so bubbles rise, and prime until a drop appears at the tip.
Is the Mounjaro vial injected the same way?
The site and depth are the same, but the vial format uses a separate syringe and needle to draw up the dose, so the preparation steps differ. Your pharmacist should demonstrate the vial technique specifically.
Sources
This article is general information, not personal medical advice. Treatment decisions are made by a registered doctor on assessment. Individual results vary.