The first time you have to inject yourself with a GLP-1 pen like Wegovy, Ozempic or Mounjaro, it can feel daunting. The good news is that it quickly becomes routine — and it is far easier than most people fear. This guide covers everything you need to know: where to inject, how to do it step by step, and what to avoid.
What kind of injection is it?
Wegovy, Ozempic and Mounjaro are all subcutaneous injections — meaning the medication is delivered into the fatty tissue just beneath the skin, not into a muscle or vein. This layer absorbs the medication slowly and evenly, which is exactly what produces the sustained, week-long effect.
The needle on these pens is very short and thin — typically 4–8 mm — and many people describe the injection as almost painless, especially once they have mastered the technique.
The three recommended injection sites
There are three areas of the body approved for subcutaneous injection with GLP-1 pens:
1. Abdomen (stomach)
The most popular site for most users. Inject into the soft fatty tissue on the side of the abdomen, staying at least two finger-widths (about 5 cm) away from the navel. The abdomen is easy to reach, has a reliably even fat layer, and lets you see exactly what you are doing. Avoid the navel itself and any scar tissue.
2. Thigh
The front outer area of the thigh — halfway between the knee and the hip — is an excellent alternative. It is practical if you are sitting, and many find it discreet. Avoid injecting here immediately after intense leg exercise, since increased blood flow can alter the rate of absorption.
3. Upper arm (back)
The back of the upper arm (the triceps area) can be used but is harder to reach on your own. Many people prefer to ask someone for help with this site, or they stick to the abdomen and thigh which they can manage independently.
Rotation: Why you should never inject the same spot twice in a row
It is critically important to rotate your injection site each week. Injecting repeatedly into exactly the same spot can, over time, cause lipohypertrophy — a build-up of fatty tissue that feels like a firm lump under the skin. This can slow the absorption of the medication and make your treatment less effective.
A good rule of thumb: move at least 1–2 cm from the previous spot, and wait at least four weeks before returning to the exact same point. Many people rotate between the abdomen one week, the thigh the next, and the upper arm the third.
Step by step: how to inject
- Wash your hands thoroughly with soap and water. Dry them well.
- Check the pen. The liquid should be clear and colourless. If it looks cloudy, discoloured, or contains particles, do not use it. If you have taken the pen straight from the fridge, let it warm up at room temperature for 15–20 minutes — cold medication can sting more.
- Choose your injection site and clean the skin with an alcohol swab or soap and water. Let the skin dry completely before injecting — otherwise it may sting.
- Attach the needle (if your pen requires it) and remove the cap.
- Pinch the skin if needed — particularly important if you are lean, to ensure you hit the subcutaneous layer rather than muscle. Hold a firm skin fold between thumb and forefinger.
- Insert the needle at a right angle (90 degrees) to the skin surface with a confident, swift motion.
- Deliver the dose:
- Ozempic: Press the dose button all the way down and hold it until the counter shows zero. Then count slowly to six before withdrawing the needle.
- Wegovy: Hold the pen against the skin and press. You will see the yellow indicator bar moving. Keep the pen pressed against the skin until the injection is complete (5–10 seconds).
- Mounjaro: Follow the instructions in the package leaflet — the lock releases automatically, and you hold the pen against the skin until a click confirms that the injection is finished.
- Withdraw the needle at the same angle you inserted it. Do not rub the skin afterwards.
- Dispose of the needle safely in a sharps container. Return it to the pharmacy when it is three-quarters full.
Common mistakes to avoid
- Forgetting to rotate. This is the most common mistake and can reduce the effectiveness of your treatment over time.
- Injecting with a cold pen. Always allow the pen to reach room temperature when taken from the fridge.
- Withdrawing the needle too early. Keep the needle in for the recommended time (typically six seconds for Ozempic) so the full dose is delivered.
- Injecting into scars, bruises or hardened skin. Avoid these areas — medication is absorbed poorly there.
- Reusing needles. Always use a fresh needle for each injection — used needles are blunt and increase the risk of infection.
Normal reactions and when to contact your doctor
A small red mark or mild itching immediately after the injection is perfectly normal and usually disappears within a day. A small pea-sized bump under the skin is also normal and is simply the medicine depot being gradually absorbed.
Contact your doctor if you notice:
- Significant redness, swelling or warmth that worsens over the first few days
- A hard lump at the injection site that does not go away
- Signs of infection: pus, fever or increasing pain
- An allergic reaction: hives, difficulty breathing, or swelling of the face and lips
How ClickDose helps
When you use dose-splitting — getting multiple doses from a single pen — precise click counting is essential. ClickDose uses your phone's microphone to automatically detect and count each click as you dial the pen, so you know exactly when to stop, whether your dose is 0.25 mg or 2 mg. It takes the stress out of dosing and lets you focus fully on getting the injection technique right.