GLP-1 receptor agonists such as semaglutide (Ozempic, Wegovy), dulaglutide (Trulicity), and liraglutide (Victoza, Saxenda) are subcutaneous injections used for type 2 diabetes and weight management. When administering a GLP-1 shot in the arm, correct site selection and technique are essential for medication efficacy and safety. The upper outer arm over the triceps area is the approved injection site, though most manufacturers recommend having another person administer arm injections due to accessibility challenges. Understanding proper injection technique, site rotation, and how to avoid common mistakes helps minimise injection site reactions and ensures optimal therapeutic outcomes. This guide provides evidence-based information aligned with UK clinical guidance.

Understanding GLP-1 Injections and Injection Sites

Glucagon-like peptide-1 (GLP-1) receptor agonists are injectable medications used primarily for managing type 2 diabetes and, in some formulations, for weight management. These medicines—including semaglutide (Ozempic, Wegovy), dulaglutide (Trulicity), and liraglutide (Victoza, Saxenda)—work by mimicking the action of the naturally occurring GLP-1 hormone. They stimulate insulin secretion in response to meals, suppress glucagon release, slow gastric emptying, and reduce appetite through central nervous system pathways.

GLP-1 medications are administered via subcutaneous injection, meaning the medication is delivered into the fatty tissue layer beneath the skin rather than into muscle or veins. This route of administration allows for gradual absorption and sustained therapeutic effect. The subcutaneous tissue is well-vascularised enough to absorb the medication effectively whilst minimising discomfort and the risk of complications.

Approved injection sites for GLP-1 receptor agonists include the abdomen (generally avoiding the area around the navel), the front and outer aspects of the thighs, and the upper outer arm. Each site offers adequate subcutaneous tissue for safe injection. The choice of injection site is largely a matter of personal preference and convenience, though some patients find certain areas easier to access or more comfortable than others. For upper arm injections, many GLP-1 devices recommend administration by another person due to the difficulty in reaching the correct area.

Understanding proper injection technique and site selection is essential for maximising medication efficacy, minimising adverse effects such as injection site reactions, and ensuring patient safety. The Medicines and Healthcare products Regulatory Agency (MHRA) and manufacturers provide detailed guidance on administration techniques, which should be reviewed with your healthcare provider or diabetes specialist nurse before commencing treatment.

Where to Give a GLP-1 Shot in the Arm

When administering a GLP-1 injection in the arm, the correct anatomical location is the upper outer arm over the triceps area. This site should be located approximately halfway between the shoulder and the elbow, on the outer back portion of the arm where there is sufficient subcutaneous fatty tissue.

To identify the proper injection zone, imagine dividing your upper arm into quarters. The outer back quarter (the area you cannot easily see when looking down at your arm) is the appropriate site. This region typically has adequate subcutaneous tissue in most adults, though individuals with very low body fat may find this site less suitable. The area should feel soft and slightly pinchable—if you can gently gather a fold of skin and underlying tissue between your thumb and forefinger, there is likely sufficient subcutaneous fat for injection.

Avoid injecting into areas with visible veins, moles, scars, bruises, or any skin abnormalities. Do not inject into the inner arm, near the armpit, or too close to the elbow or shoulder joints. These areas either lack adequate subcutaneous tissue or contain important blood vessels and nerves that should not be disturbed.

For most GLP-1 devices, upper arm injections should be administered by another person rather than self-administered. This is specifically stated in many product information leaflets and is not merely a matter of convenience. The upper arm injection site is difficult to reach correctly on your own, and having assistance ensures the medication is delivered into the subcutaneous tissue rather than muscle. Many patients find the abdomen or thigh more accessible for self-injection. Your practice nurse or diabetes specialist can demonstrate the proper technique and help determine whether arm injection is appropriate for your circumstances.

Step-by-Step Guide to Injecting GLP-1 in Your Arm

Preparation is essential for safe GLP-1 administration. Begin by washing your hands thoroughly with soap and warm water, then dry them completely. If your GLP-1 pen is refrigerated, you may remove it approximately 30 minutes before injection to allow it to reach room temperature (following your specific product's storage guidelines), as cold medication can cause discomfort. Check the medication's appearance—it should be clear and colourless (or as specified in your product information). Do not use the medication if it appears cloudy, discoloured, or contains particles.

Gather your supplies: your GLP-1 pen, a new needle (if using a pen with replaceable needles), and an alcohol wipe or cotton wool with surgical spirit. Keep your NHS-provided sharps container nearby for immediate safe disposal of used needles.

To inject in your arm, you will need assistance as specified in most product guidelines. Have your helper identify the correct injection site on the upper outer arm over the triceps area. Clean the injection site with an alcohol wipe using a circular motion, moving outward from the centre, then allow the area to air dry completely (approximately 10–15 seconds). Injecting into wet skin can cause stinging.

If using a pen with replaceable needles, attach a new needle according to the manufacturer's instructions, remove both the outer and inner needle caps, and perform a flow check/priming if required by your specific device. Follow your device's specific instructions for injection technique. For many devices, you'll need to pinch the skin at the injection site gently to lift the subcutaneous tissue away from the underlying muscle. Insert the needle at the angle recommended for your device (often 90-degrees for standard needles) with a quick, dart-like motion. Press the injection button fully and hold it down whilst counting slowly as directed in your device instructions (typically 6–10 seconds) to ensure complete dose delivery.

Withdraw the needle at the same angle it was inserted, release the skin fold, and apply gentle pressure with a clean cotton wool ball if needed. Do not rub the injection site, as this may affect absorption. Dispose of the needle immediately in your NHS-provided sharps container. When full, arrange collection or return through your local council or pharmacy services—never place sharps in household waste. Record the injection site and date to help with site rotation.

Rotating Injection Sites and Best Practices

Systematic rotation of injection sites is crucial for preventing lipohypertrophy (thickening of fatty tissue) and lipoatrophy (loss of fatty tissue), both of which can impair medication absorption and lead to unpredictable blood glucose control. Repeatedly injecting into the same spot causes localised tissue changes that reduce the subcutaneous tissue's ability to absorb medication effectively.

The recommended approach is to rotate between different anatomical areas (abdomen, thighs, and arms) as well as different spots within each area. For example, if you inject weekly, you might use your abdomen one week, your right thigh the next, your left thigh the following week, and your arm (with assistance) the fourth week, then return to the abdomen in a different location. For daily injections, rotate within the same general area (e.g., different spots on the abdomen) for a week, then move to a different anatomical site the following week.

Maintain a minimum distance of 2–3 centimetres between injection sites, even within the same anatomical area. Some patients find it helpful to imagine a clock face on their abdomen or to keep a simple diary noting which site was used on which date. Some people use smartphone applications to track their injection sites, though the pens themselves do not automatically track sites.

Additional best practices include: never reusing needles, as this increases infection risk and causes needle dulling that makes injections more painful; storing your medication properly (refrigerated before first use, then either refrigerated or at room temperature as per product guidelines); inspecting injection sites regularly for signs of reaction; and following your specific GLP-1 medication's timing instructions. Most GLP-1 medications (including semaglutide, dulaglutide, and liraglutide) do not need to be timed with meals, though some exceptions exist (such as immediate-release exenatide). If you notice persistent lumps, hardness, or skin changes at injection sites, contact your GP or diabetes nurse, as you may need to avoid that area temporarily and receive guidance on technique refinement.

Common Mistakes and How to Avoid Injection Site Reactions

Several common errors can compromise GLP-1 injection safety and efficacy. One frequent mistake is injecting too deeply into muscle tissue rather than subcutaneous fat. This occurs when the needle is too long for the amount of subcutaneous tissue present or when insufficient skin is pinched before injection. Intramuscular injection can cause increased pain, bruising, and altered medication absorption. If you are lean or using the arm site, discuss with your healthcare provider whether a shorter needle (4mm or 5mm) might be more appropriate for pens with replaceable needles. Note that some devices like dulaglutide have fixed needles.

Failing to rotate injection sites adequately leads to lipohypertrophy, which appears as firm lumps or thickened areas under the skin. These areas have reduced blood flow and impaired absorption capacity. Always examine your injection sites visually and by touch, and avoid any areas that feel different from surrounding tissue. If lipohypertrophy develops, it may take several months of avoiding that site for the tissue to recover.

Injecting cold medication directly from the refrigerator is a common cause of injection site discomfort and can trigger localised reactions. Allow your GLP-1 pen to reach room temperature before use, following storage guidelines. Similarly, rubbing the injection site immediately after injection can cause bruising and may affect medication absorption—apply gentle pressure only if needed.

Injection site reactions such as redness, itching, swelling, or mild pain can occur with GLP-1 medications and are usually mild and transient. These reactions typically resolve within a few days without intervention. To minimise reactions: ensure proper injection technique, rotate sites consistently, avoid injecting into areas with skin conditions, and never reuse needles.

When to seek medical advice: Contact your GP or diabetes specialist nurse if you experience severe pain, significant swelling, spreading redness, warmth suggesting infection, or persistent lumps lasting more than two weeks. Call 999 or go to A&E immediately if you experience signs of a serious allergic reaction (widespread rash, difficulty breathing, facial or throat swelling). Whilst serious injection site complications are rare, prompt assessment ensures appropriate management. Your healthcare team can review your injection technique, suggest alternative sites, or investigate whether the reaction represents a true medication allergy requiring treatment adjustment. Suspected side effects can be reported through the MHRA Yellow Card scheme (yellowcard.mhra.gov.uk), contributing to ongoing medication safety monitoring.

Frequently Asked Questions