Where to Inject Wegovy and Ozempic: A Step-by-Step UK Guide

Getting the injection right matters more than most patients realise. Injecting consistently into the same spot, without rotating, causes lipohypertrophy: the build-up of fatty tissue under the skin that impairs drug absorption and reduces effectiveness. Injecting into the wrong area risks injecting into muscle rather than subcutaneous fat, which changes the absorption profile of the medication.

This guide covers the three approved injection sites for Wegovy, Ozempic, and Mounjaro, how to rotate between them, the technique for self-injection, and what to watch for.

The Three Approved Injection Sites

All semaglutide and tirzepatide products are designed for subcutaneous injection, into the layer of fat just below the skin, not into muscle or vein.

1. Abdomen (Stomach)

The abdomen is the most commonly used injection site and generally the easiest to use for self-injection. Use the fatty tissue on either side of the navel, but stay at least 5cm (2 inches) away from the belly button itself. Avoid the waistline area where clothing sits tightly.

Advantages:

• Largest available subcutaneous fat area
• Easy to access for self-injection
• Consistent absorption rate

Avoid:

• Stretch marks (absorption may be unpredictable)
• Existing bruises or broken skin
• Scar tissue from previous surgery

2. Thigh (Front or Outer)

The front of the thigh, roughly midway between the knee and hip, is the second most common site. Use the outer portion, not the inner thigh where skin is thinner and the injection is more painful.

Advantages:

• Easy to see and access for self-injection
• Good for patients with minimal abdominal fat

Avoid:

• The inner thigh
• The knee joint area
• Existing bruises or skin changes

3. Upper Arm (Outer Area)

The outer, fatty area of the upper arm, approximately where a vaccine would be given, is an approved site. This is harder to self-inject and generally requires a second person if you are using it regularly.

Advantages:

• Useful if the abdomen and thighs are over-rotated
• Some patients prefer it for discretion

Avoid:

• Using this site for self-injection without practice, the angle is difficult
• The deltoid muscle itself (aim for the fatty tissue just below the shoulder point)

Why Rotation Matters

Injecting repeatedly into the same small area causes lipohypertrophy, the build-up of fibrous, fatty tissue that forms as a response to repeated needle trauma and insulin/peptide exposure. Lipohypertrophic tissue:

• Absorbs medication irregularly and unpredictably
• Can lead to variable drug plasma levels
• May cause apparent loss of efficacy despite taking the correct dose

This is well-documented in insulin users, and the same principle applies to semaglutide and tirzepatide, both are subcutaneous injections with similar administration principles.

A systematic rotation strategy prevents lipohypertrophy. The simplest approach: divide each site into a grid of squares roughly 2-3cm apart, and move one square along each week. When you complete the grid for one site, move to the next site before returning.

Example rotation cycle (3-site rotation):

• Week 1: Abdomen, left side
• Week 2: Abdomen, right side
• Week 3: Left thigh
• Week 4: Right thigh
• Week 5: Abdomen, left side (further along the grid)

Step-by-Step Injection Technique

Preparation

1. Wash your hands thoroughly with soap and water for at least 20 seconds before handling the pen.

2. Inspect the pen. Check the medication window, the liquid should be clear and colourless. Do not use the pen if the liquid is cloudy, coloured, or contains visible particles. Do not use the pen if it has been frozen.

3. Check the expiry date on the pen label. Do not use expired medication.

4. Allow the pen to reach room temperature if it has been in the fridge. Injecting cold medication is more uncomfortable. Allow 30 minutes out of the fridge before injecting.

5. Clean the injection site with an alcohol swab and allow it to dry fully before injecting. Injecting before the alcohol dries can cause a stinging sensation.

The Injection

1. Remove the pen cap. For Ozempic and Wegovy, screw on a new needle for each injection. For Mounjaro, the pen is pre-attached. Follow the specific instructions in your pen's leaflet.

2. Perform the flow check (for pens that require it), hold the pen with the needle pointing up, select the flow check symbol, press the dose button until a drop appears at the needle tip. This confirms the needle is primed and unobstructed.

3. Select your dose as directed by your prescriber.

4. Hold the pen firmly against the clean, dry injection site. You do not need to pinch the skin unless you are very lean, the needle length is calibrated for typical subcutaneous fat depth.

5. Press the button firmly and hold for a full 6 seconds (Wegovy/Ozempic) or as directed (Mounjaro). The count of 6 seconds ensures the full dose is delivered and the medication does not leak back through the needle track.

6. Remove the pen straight out, do not twist or angle it.

7. Do not rub the injection site. Rubbing can cause bruising and may push medication into capillaries.

Disposal

Needle disposal is a legal and safety requirement. Used needles must go into a sharps bin, do not put them in household bins. The NHS and local councils provide sharps bin collection. Your pharmacy may also accept used sharps bins for disposal. Ask your prescriber or pharmacist about the sharps waste collection arrangements in your area.

Recognising Lipohypertrophy

Lipohypertrophy feels like a soft, rubbery lump under the skin, distinct from the surrounding tissue. In some cases, the overlying skin looks slightly different, paler, or with a slightly uneven texture. The area may be less sensitive to pain than normal tissue.

If you find a lump at an injection site:

• Stop injecting into that area immediately
• Do not inject into it again until it has fully resolved, this can take weeks to months
• Tell your prescriber at your next review
• Use alternative sites in the meantime

Injecting through a lipohypertrophic area gives unpredictable absorption. If you have been injecting consistently into a lump for weeks without noticing, variable drug levels may partly explain any inconsistency in your weight loss response.

Bruising and Bleeding

Small amounts of bleeding or bruising at the injection site are normal and not concerning. Apply gentle pressure with a clean finger for 1-2 minutes after injecting if there is bleeding. Do not rub.

If you are on anticoagulants (warfarin, rivaroxaban, apixaban, etc.), bruising may be more pronounced. This is expected. Bleeding risk from subcutaneous injection is very low on anticoagulants, but check with your prescriber if bruising is severe or widespread.

Common Injection Mistakes

Injecting too close to the navel: The area within 5cm of the belly button is less predictable for absorption and more prone to bruising. Stay 5cm away.

Injecting through clothing: Do not inject through clothing, this increases infection risk and may cause the needle to deflect.

Reusing needles: Each needle should be used once only. Reusing needles causes blunting (making the injection more painful), increased infection risk, and potential changes in needle integrity that affect delivery accuracy.

Not holding for 6 seconds: Releasing the button early is one of the most common causes of partial dosing. Count to 6 before withdrawing.

Injecting into cold skin directly from the fridge: Allow the pen to reach room temperature for at least 30 minutes before injecting.

Related Guides

For the dose escalation schedule and how to manage each step, see /guides/glp1-dose-escalation-guide-uk.

For managing nausea during the early weeks of treatment, see /guides/nausea-management-semaglutide-uk.

For the original injection technique guide covering Ozempic specifically, see /guides/how-to-inject-ozempic-uk.

For storage and travel information for your pen, see /guides/glp1-storage-temperature-uk.