How do you inject Mounjaro? A step-by-step guide

What do you need before your first Mounjaro 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, and a clean, well-lit surface to lay everything out on makes the routine easier to repeat each week.

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.

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.

What is the best place to inject Mounjaro for weight loss?

No single site is best for weight loss. The stomach, the front of the thigh and the back of the upper arm all deliver tirzepatide into the same fatty layer, and absorption is reliable at each. The best place to inject Mounjaro is the site you can reach comfortably and rotate consistently.

Most people settle on the stomach. The area is large, easy to see, and simple to rotate: treat the skin around the belly button as a clock face, stay at least 5 cm out, and move along an hour each week.

The arm is the exception: the back of the upper arm is hard to reach properly on yourself, so it is meant for injections given by someone else. If a partner will be giving your injection, ask your pharmacist to walk them through the same steps; the technique does not change.

Whoever injects, weekly rotation matters more than the site itself. Injecting one spot repeatedly can build firm fatty lumps under the skin, and medicine injected into those lumps absorbs unpredictably.

How do you use the Mounjaro KwikPen step by step?

Using the Mounjaro KwikPen takes eight steps: wash your hands, check the pen, attach a new needle, prime, dial the dose, inject, hold for a slow count of five, and check the window shows 0. The numbered sequence below follows the official KwikPen instructions for use.

1. Wash your hands with soap and water.
2. Pull the pen cap straight off and check the medicine and expiry date.
3. Wipe the red inner seal at the top of the cartridge with an alcohol swab.
4. 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.
5. 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.
6. 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.
7. 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.
8. 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.

How do you inject the second dose of Mounjaro?

The same way as the first: attach a new needle, prime the pen, dial 1, inject into a fresh spot and hold the knob down for a slow count of five. Priming happens before every injection, not only the first, and each dose needs its own needle.

Doses two, three and four come from the same pen, which holds enough liquid for four full doses plus the priming amounts, so priming does not shorten your medicine.

Keep the same weekly day, and move the site a few centimetres from last week's spot, or switch sides. If you cannot remember where the last injection went, a note on your phone or on the pen box solves it.

To change your injection day, leave at least three days (72 hours) between the last dose on the old day and the first on the new one.

How do you inject Mounjaro with a syringe?

The single-dose vial format uses a separate syringe instead of a dial. You draw the full contents of the vial into the syringe, clear the air, and inject under the skin at the same sites the pen uses. Site, depth and rotation stay the same; only the preparation differs.

The sequence: wash your hands, check the liquid is colourless to slightly yellow, wipe the vial top with an alcohol swab, draw up the entire contents, hold the syringe needle-up and press out any air bubbles, then inject at 90 degrees and push the plunger fully.

The vial is single-use. Discard it straight after the injection, even if a little liquid remains, and put the syringe and needle in your sharps container. Nothing is kept for next week.

Ask your pharmacist to demonstrate the draw-up before your first vial injection; small errors slip in more easily than with the pen. The two formats, and which one your pharmacy is likely to stock, are compared in Mounjaro vial vs pen.

How do you know if you injected Mounjaro correctly?

Check the dose window. A 0 in the window after the injection confirms the pen delivered the full dose. A small drop on the needle tip afterwards, a spot of blood on the skin, or a brief sting at the site are all normal, and none of them means the dose was lost.

If the window shows any number other than 0, the injection is unfinished. Put the needle back into your skin and complete the push until the 0 appears; do not redial or start a new dose.

A wet patch on the skin bigger than a drop usually means the needle came out before the count finished. Do not inject extra to compensate; hold the full count of five next time, and mention it to your pharmacist if it keeps happening.

If you are unsure whether a dose went in, phone your doctor or the pharmacy rather than repeating it. Injecting much more than your dose is a same-day call to your doctor.

What do you do after the injection?

If you see a spot of blood, press lightly with gauze or a cotton ball for a few seconds. Do not rub the site; rubbing pushes medicine around and can cause bruising. Most weeks there is nothing to see at all, and the site needs no plaster or special care.

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.

Which Mounjaro injection mistakes are most common?

Five habits cause most injection problems: reusing needles, skipping the prime, pulling the needle out early, using the same spot every week, and storing the pen with a needle attached. None of them ruins treatment on its own, but each makes injections sorer or doses less reliable.

Recheck the list every month or so; habits slip once the routine feels automatic.

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. Cold liquid stings more than room-temperature liquid, so 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.

How do you store the Mounjaro KwikPen?

Unused pens live in the fridge at 2 to 8 degrees Celsius. Once a pen is in use it may stay out of the fridge at room temperature up to 30 degrees, and from that first use it lasts 30 days, which covers its four weekly doses. Never freeze a pen; a frozen one is discarded even after it thaws.

Keep the pen 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, and pharmacies sell small purpose-made containers for exactly this reason.

Many pharmacies, 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.

What does the Mounjaro injection cost in South Africa?

Retail price lists published in 2026 put the Mounjaro KwikPen at roughly R3,600 to R8,200 per pen depending on strength. Each pen holds four weekly doses, so those figures work out to roughly R900 to R2,050 per injection. We do not sell medicine. Prices vary by pharmacy and dose; confirm with your pharmacy.

The medicine price is regulated. South Africa's Single Exit Price system sets one national price per pack, so pharmacies differ only by a regulated dispensing fee. The registry at mpr.gov.za publishes the current figure for each strength.

Pen needles and a sharps container sit outside the pen price and are bought separately at the pharmacy. What drives the total monthly figure, including how the cost climbs as the dose steps up, is unpacked in how much Mounjaro costs in South Africa.

Frequently asked questions