Mounjaro, Wegovy and Ozempic are injected under the skin, into the abdomen or the thigh. The injection goes into the fatty layer and not into muscle. For Mounjaro, the prescribing information recommends that another person give the injection in the back of the upper arm. The exact pen technique differs by medication and device, so follow the instructions supplied with your prescribed pen. Change the site with every weekly dose, never share a pen with anyone, and put used needles or single-use pens straight into a sharps container.
- The injection sites are the abdomen and the thigh, with the back of the upper arm as a third site.
- The FDA prescribing information for Mounjaro recommends that another person give the injection in the upper arm. The Ozempic label lists the upper arm without that restriction.
- Both labels instruct you to rotate the site with each dose, and the Ozempic label asks for a different site each week within the same region.
- The FDA prescribing information for Ozempic states that pens must never be shared between patients, even if the needle is changed, because of the risk of transmitting blood-borne infection.
- If your pen uses a removable needle, use a new one for every injection and remove it before you store the pen. A single-use pen with a built-in needle goes into the sharps container whole.
- If medication leaks from the site, do not inject a second dose. Contact the clinic instead.
- Endocare’s doctors are available to support patients with advice if you are unsure about your technique at any point.
A weekly weight loss injection is given subcutaneously, which means into the fatty layer directly under the skin. All are injected subcutaneously, but the exact pen technique differs by medication and device, so follow the instructions supplied with your prescribed pen. What follows covers the parts that are the same for every pen: the sites, the rotation, the skin, and what to do afterwards.
Where do you inject a weekly weight loss medication?
The FDA-approved prescribing information for Mounjaro instructs that the medication is injected subcutaneously in the abdomen or the thigh, and that another person should inject into the back of the upper arm. The FDA prescribing information for Ozempic lists the abdomen, the thigh and the upper arm without that restriction, and the Wegovy prescribing information lists the same three.
Where the labels differ, we ask patients to follow the one for the medication they are prescribed. None of them ranks the sites, and no site produces more weight loss than another.
Abdomen
The abdomen is the site most patients find easiest to reach, and the fatty layer there is often the most generous. Stay at least five centimetres from the navel.
Thigh
The front and outer part of the upper thigh is suitable, particularly if the abdomen has become tender. Avoid the inner thigh and the area close to the knee.
Back of the upper arm
For Mounjaro, the prescribing information recommends that another person give the injection in the back of the upper arm, as this area can be difficult to reach and inject correctly yourself.
How to rotate your injection sites
We ask every patient to rotate the site with every dose. The Mounjaro prescribing information instructs patients to rotate injection sites with each dose. The Ozempic label asks you to use a different site each week when you are injecting within the same region of the body.
A simple rotation is to alternate between four areas. Use the left side of the abdomen one week, the right side the next, the left thigh the week after and the right thigh the week after that, then start again. Keep a note of which site you used.
Using one spot every week can raise the chance of a local reaction and of a firm lump forming under the skin, which can change how the medication is absorbed.
Step by step: your weekly injection
- Wash your hands with soap and water.
- Take the pen out of the fridge and check it. Check the expiry date, and look at the liquid through the window. It should be clear and colourless. Do not use the pen if the liquid is cloudy or has particles in it.
- Prepare the pen as its own instructions describe. Some pens need a new needle attached for each injection, while single-use pens have a built-in needle and need no preparation beyond removing the cap.
- Choose your site for this week, and check that it is a different one from last week.
- Clean the skin with an alcohol swab and let it dry completely before you inject.
- Place the pen against the skin and follow the injection and hold-time instructions for your specific device.
- Remove the pen straight out, at the same angle you put it in.
- If your pen uses a removable needle, put the needle straight into your sharps container without recapping it, and store the pen without a needle. If your pen is single-use, put the whole pen into the sharps container.
Do not rub the site afterwards. If a small drop of blood appears, press gently with clean gauze.
Does the injection hurt?
Most patients find it manageable. The needle is very fine and short, and it goes into fatty tissue rather than muscle, which has fewer pain receptors. Some patients report that the alcohol swab stings more than the needle.
If it does hurt, the most common reasons are injecting before the alcohol has dried, or injecting into muscle where the fatty layer is thin. Cold medication straight from the fridge can also sting, and we suggest letting the pen sit at room temperature for a few minutes first.
What to do if the medication leaks out of the injection site
Do not inject a second dose. A small drop at the injection site can happen and does not necessarily mean you have lost a significant amount of medication. Taking another injection could result in receiving too much medication.
If a noticeable amount leaks out, contact the clinic and tell us what happened. Your doctor will advise you before your next weekly dose. Holding the pen in place for the time your pen instructions give, and removing it straight out, can help prevent leaks.
Bruising, redness and lumps at the injection site
Small bruises are common and are not a sign that anything went wrong. They happen when the needle passes a small blood vessel. Redness and mild itching at the site are also reported, and both typically settle within a day or two.
We recommend contacting the clinic if a reaction is severe, if it is spreading, if it is painful rather than tender, or if a lump persists between doses. Our page on Mounjaro side effects covers injection-site reactions alongside the other side effects to expect.
How to store your pen between doses
Keep unopened pens in the fridge. Once you start a pen, follow the storage instructions for that medication, because the in-use period and the maximum room temperature differ between them.
In the UAE, heat is the main storage risk. Do not leave a pen in a car, and use an insulated bag when you travel with one. A pen bought outside a licensed pharmacy may already have been stored incorrectly; our article on buying Mounjaro online in the UAE explains the risks.
What to do with the used needle
Put the used needle, or the whole single-use pen, into a sharps container immediately after you inject. The FDA’s guidance on safe sharps disposal instructs you to place used needles straight into a sharps disposal container. It also says not to throw loose needles into household waste, flush them, or put them in a recycling bin, and it advises against removing, bending, breaking or recapping a needle used by another person.
When the container is full, seal it and label it. Ask our team or your pharmacy where to return it, because collection arrangements vary between emirates and between facilities.
What happens at Endocare when you start injecting
Patients can self-inject at home, and the process is simple and generally painless. If you prefer, a nurse at the clinic will give your first doses until you feel confident injecting on your own.
Your endocrinologist will review your dose with you at each monthly follow-up, in increments of roughly four weeks, and there is no automatic step up. Our Mounjaro dosage guide sets out each dose, and your first month on Mounjaro covers what to expect. Patients prescribed Wegovy or Ozempic follow the same monthly review.
Patients should not decide by themselves to start a GLP-1 medication. A doctor’s review is critical to ensure the treatment is safe and appropriate for the individual.
Frequently asked questions
Is it better to inject Mounjaro in the stomach or the thigh?
Neither is better. The FDA prescribing information lists both and does not rank them, and no site produces more weight loss than another. Change the site with every dose.
Does the Mounjaro injection hurt?
Most patients find it manageable. The needle is fine and short, and it goes into fatty tissue rather than muscle. Letting the pen reach room temperature, and letting the alcohol dry, can reduce the sting.
What should I do if the medication leaks out after I inject?
Do not inject a second dose. A small drop at the injection site can happen and does not necessarily mean you have lost a significant amount of medication. Taking another injection could result in receiving too much medication. If a noticeable amount leaks out, contact the clinic and your doctor will advise you before your next weekly injection.
Can I inject into the same spot every week?
No. The Mounjaro prescribing information instructs you to rotate injection sites with each dose. Using one spot repeatedly can raise the chance of a local reaction and of a lump forming, which can change how the medication is absorbed.
How do I dispose of used needles in the UAE?
Put each used needle, or the whole single-use pen, straight into a sharps container without recapping. When the container is full, seal and label it, then ask our team or your pharmacy where to return it, because arrangements vary between emirates.
Can someone else give me the injection?
Yes. For Mounjaro, the prescribing information recommends that another person give the injection in the back of the upper arm, as this area can be difficult to reach and inject correctly yourself.
If you are about to start a weekly injection and would prefer not to give the first one yourself, book a consultation. A nurse at the clinic can give your first doses until you feel confident injecting on your own.
Our doctors are available to support patients with advice between appointments. If you are unsure about your technique at any point, contact the clinic.
