How to Inject Mounjaro: Where to Inject, the Best Site, and Pen, KwikPen and Vial Steps

Mounjaro is injected under the skin (subcutaneously) in the abdomen, the thigh, or the back of the upper arm.1 You can inject your own stomach or thigh. The back of the upper arm is for another person to inject.1,2

Sources: Mounjaro label and Instructions for Use.1,2,3

Change (rotate) your injection site each week. You can use the same body area, but choose a different spot within it.2 The vial instructions explain why: rotating lowers the risk of lipodystrophy (pits or thickened skin) and localized cutaneous amyloidosis (lumps) at injection sites.4

Do not inject where the skin has pits, is thickened, has lumps, or is tender, bruised, scaly or hard, and do not inject into scars or damaged skin.4

No injection site works better than another: the Mounjaro label reports similar drug exposure whether tirzepatide is injected in the abdomen, thigh or upper arm.1 The site does not change how much tirzepatide reaches your blood, so it should not change weight loss either.1

Lilly's pen instructions say your healthcare provider can help you choose the site that is best for you.2 In practice, the best place is one you can reach comfortably, with healthy skin, and that you can rotate within each week.

Mounjaro itself is approved for type 2 diabetes, not weight loss.1 The weight-management brand of tirzepatide is Zepbound; see how to inject Zepbound and Mounjaro vs Zepbound.

For how well it works, no; for skin health, rotating does matter.1,4 Exposure is similar across the three sites, but repeated injections in the exact same spot raise the risk of skin changes.1,4

Use the thigh, or the stomach area at least 2 inches from the belly button.3 Place the device or needle at the chosen spot and follow the steps for your presentation below.

The single-dose pen has a hidden needle and delivers the full dose in one press: place it flat on the skin, unlock it, and press and hold the purple button for up to 10 seconds.2

1. Take the pen out of the refrigerator. Check the label for the right medicine, dose and expiration date.2
2. Make sure the medicine is not frozen or cloudy, has no particles, and is colorless to slightly yellow. Wash your hands.2
3. Choose the injection site.2
4. Make sure the pen is locked, then pull the gray base cap straight off. Do not put it back on, and do not touch the needle.2
5. Place the clear base flat against your skin, then unlock by turning the lock ring.2
6. Press and hold the purple injection button for up to 10 seconds. The first click means the injection started; the second click means it is done.2
7. The dose is complete when the gray plunger is visible. Put the used pen in a sharps container.2

It is not necessary to warm the pen to room temperature, and air bubbles in the pen are normal.2 If you do not see the gray plunger, Lilly's instructions say to call 1-800-545-5979.2

The Mounjaro KwikPen holds 4 fixed weekly doses and needs a new pen needle and priming before every injection.3 Pen needles are not included.3

1. Wash your hands, pull off the pen cap and check the pen and label.3
2. Wipe the red inner seal with an alcohol swab, then twist on a new pen needle.3
3. Remove the outer needle shield (keep it) and the inner needle shield.3
4. Prime: turn the dose knob until you hear 2 clicks, hold the pen needle up, tap the cartridge, then push the knob in and count slowly to 5. A drop at the tip means the pen is primed.3
5. Turn the dose knob all the way until it stops and the dose icon shows in the window. Do not count clicks.3
6. Insert the needle, push the knob in until it stops, and hold for a slow count of 5 before removing the needle.3
7. Confirm the icon is in the dose window, recap the needle with the outer shield, unscrew it into a sharps container and replace the pen cap.3

After 4 doses, throw the pen away even if medicine is left. Do not inject the leftover medicine or transfer it into a syringe.3 Never share a KwikPen, even with a new needle, because of the risk of blood-borne infection.1

A single-dose pen holds 1 dose; a KwikPen holds 4 weekly doses.1 Single-dose pens come in cartons of 4.1

Mounjaro vials are drawn up with a separate syringe and needle: a single-dose vial holds 0.5 mL, and the label recommends a 1 mL syringe that can measure a 0.5 mL or 0.6 mL dose.1,4 Always use a new syringe and needle for each injection.1

1. Pull off the plastic cap and wipe the rubber stopper with an alcohol swab.4
2. Attach the needle if needed, draw 0.5 mL of air into the syringe, and push it into the vial.4
3. Turn the vial upside down and slowly pull the plunger past the 0.5 mL line. Tap out air bubbles and push the plunger back to 0.5 mL.4
4. Insert the needle under the skin and push the plunger. Keep the needle in for at least 5 seconds.4
5. If you see blood, press with gauze; do not rub. Do not recap the needle.4

A multi-dose vial holds 4 doses of 0.6 mL each.1 Never mix Mounjaro with insulin in the same syringe; inject them separately, and not right next to each other.1

Once a week, at any time of day, with or without meals.1 If you miss a dose, you can take it within 4 days (96 hours); after that, skip it.1 See our Mounjaro dosage guide for the full schedule and our missed dose tool.

Keep Mounjaro in the refrigerator at 36°F to 46°F (2°C to 8°C), in the original carton, and never freeze it.1

Source: Mounjaro label, section 16.1 Our guide to GLP-1 storage and refrigeration covers travel and temperature questions.

What should I do with used pens and needles? Put them in an FDA-cleared sharps container right away. If you do not have one, a heavy-duty plastic household container with a tight, puncture-resistant lid can work.2 Local rules vary; the FDA lists them by state.5

Is bleeding at the injection site normal? A drop of liquid or blood on the skin is normal. Press a cotton ball or gauze on the spot and do not rub it.2

Do I need to hold the button down on the single-dose pen? It is not required, but it may help keep the pen steady. Do not lift the pen before the second loud click.2

Can someone with vision problems use the pen? Not without help from a person trained to use it.2 The label does not recommend the KwikPen for self-injection by people who are visually impaired.1

Should I pinch the skin? The vial instructions say your healthcare provider should tell you whether to pinch the skin before injecting.4

Your device type can affect what you pay. Our Mounjaro cost guide compares pens, KwikPens and vials, and how to get tirzepatide online compares prescribing services. If you are deciding between tirzepatide brands, see Mounjaro vs Ozempic and our list of the best GLP-1 options. Read about Mounjaro side effects before your first injection.

This article is for information only and is not medical advice. Follow the Instructions for Use for your own Mounjaro presentation and the training from your healthcare provider. Mounjaro is a prescription drug with real risks and side effects.