Dr Nick Fuller
Leading Obesity Expert at the University of Sydney and founder of Interval Weight Loss.
Injecting semaglutide might feel daunting the first time, but with clear, medically accurate guidance you can do it confidently and safely. Semaglutide injections — whether for weight management (Wegovy) or blood sugar control (Ozempic) — are designed for weekly subcutaneous (under-the-skin) use, and are widely prescribed because of their reliable track record in clinical trials. The weekly regimen and pre-filled pens make them simpler to use than many older injectable medicines, but correct technique is crucial for full dosing, comfort and reducing skin irritation or infection.
This guide combines official prescribing information and manufacturer instructions so you know exactly what to prepare, how to inject semaglutide in the right places, how to perform each step and what to avoid — all based on trusted sources rather than hearsay.
Factors to Consider Before Injecting Semaglutide
Your clinician determines your starting dose and any follow-up escalations based on your health goals and tolerability. Always inject the exact dose prescribed — semaglutide pens often show the dose clearly on a dial or label, and Wegovy pens are pre-set for a single weekly dose.
Semaglutide is given once weekly on the same day each week at a time that fits your routine. Consistency supports steady levels in the body and helps maintain effects. You can inject with or without food, and at any time of day, so long as you stick with your weekly rhythm.
Unused pens should be stored in the refrigerator until needed; once in regular use they may be kept at room temperature within specified limits. Always check storage instructions on the packaging and never use pens that have been frozen, discoloured or damaged.
Before injecting, confirm that the pen has not passed its expiry date. Injecting expired medication may deliver an ineffective dose.
Preparing the skin reduces the risk of infection. Use an alcohol swab or wash with soap and water, and allow the area to fully dry before injecting. Touching the cleaned area again can reintroduce bacteria.
Choose a site that you can access comfortably and confidently. Some people prefer thighs because they’re easy to reach, while others use the abdomen or upper arm. Rotating sites each week helps reduce skin irritation.
Supplies Needed to Inject Semaglutide
Semaglutide pen (Wegovy or Ozempic) from your pharmacy
New needle or pen needle for sharps safety
Alcohol swabs to clean skin before injecting
Cotton ball or gauze for use after injecting
Sharps disposal container for needles and used pens
Where to Inject Semaglutide
Semaglutide should only be injected into the fatty layer under the skin, not into muscle or a vein.
The abdomen (lower stomach) is commonly used, but keep at least 2 inches (about a hand’s width) away from your navel. This area tends to be less sensitive and is easy to reach for most people.
The front of the thigh is another safe option. Many people find it comfortable, especially when they’re starting out, and it’s easy to see and clean before injecting.
The outer upper arm can also be used, though it’s often easier if someone else can help you see and reach the exact spot. As with other sites, rotate locations to prevent irritation.
Tips to Prepare the Injection
Clean hands reduce the chance of introducing bacteria into your skin or the injection pen. Take your time washing with soap, then dry thoroughly.
Look through the pen window to ensure the liquid is clear and colourless; do not use it if it’s cloudy or discoloured.
Use an alcohol swab or clean water and soap to swab the area, then let the site dry completely before injecting — this ensures the skin is free of germs.
Always attach a new sterile needle just before injecting. Reusing needles increases infection risk and can cause dosing inaccuracies.
If the pen has been refrigerated, letting it warm slightly can make the injection more comfortable and ensure smooth flow. Follow manufacturer advice on how long it can safely stay out before use.
Step-by-Step Guide to Inject Semaglutide
Remove the pen cap and attach a new needle, twisting it on until it fits securely. If you’re using an Ozempic pen, you may also need to perform a flow check on the first use — turning the dose selector to the flow symbol and pressing until a drop appears at the needle tip.
For semaglutide pens that allow dosing (like Ozempic), turn the dose selector until your prescribed amount is displayed. Wegovy pens are usually single-dose and don’t need adjusting.
Gently pinch a fold of skin at your clean injection site; this creates a stable surface for subcutaneous injection and helps reduce discomfort.
Insert the needle straight into the pinched skin at a 90-degree angle. Make sure it’s firmly under the skin but not into the muscle.
Press the injection button or push the pen firmly against your skin until the medication is delivered. For Wegovy pens, you’ll hear two clicks — the first when the injection starts and the second while it continues — and the entire process takes about 10 seconds of firm pressure.
Keep the needle in place for a few seconds after delivery to ensure the full dose enters your tissue before slowly lifting away.
What to Do After Injecting Semaglutide
Detach the used needle from the pen immediately to prevent contamination or injury.
Place the needle into a sharps disposal container — never throw it in regular household waste. Follow local guidelines for disposing of medical sharps.
Avoid rubbing your injection site, as this can increase irritation or bruising. A gentle touch or light pressure with gauze is fine if there’s a small amount of bleeding.
Check the area over the next day or two for swelling, redness or persistent discomfort. Mild reactions can be normal, but prolonged symptoms should be discussed with a clinician.
Keeping a weekly log of the date, time and site helps you rotate locations and track consistency in your injections.
Possible Side Effects on the Injection Site
Slight redness around the site can occur and usually disappears within a day or two.
Some mild swelling is normal as your body responds to the needle entry; it should settle quickly.
You may feel mild discomfort or pressure, but sharp pain that persists isn’t expected and should prompt medical advice.
Occasional bruising can result from small blood vessel trauma; it typically fades on its own.
Itching as the skin heals is normal but should resolve within a couple of days.
Things to Avoid While Injecting Semaglutide
Reusing needles — this increases infection risk and can blunt needle sharpness.
Injecting into muscle or vein — semaglutide is designed for subcutaneous use only.
Skipping site rotation — repeated use of the same exact spot can cause irritation or lumps.
Using damaged needles — never inject with a bent, dull or contaminated needle.
Injecting through clothing — always inject directly into clean, bare skin.
Following official guidance from product instructions and clinical sources ensures you inject semaglutide safely and effectively each week. If you’re uncertain about any part of this process, your healthcare provider or pharmacist can demonstrate the technique and answer your questions.
Dr Nick Fuller is the founder of Interval Weight Loss and is a leading obesity expert at the University of Sydney with a Ph.D. in Obesity Treatment. Dr Fuller is also the author of three best-selling books and his work been published in top ranked journals in the medical field, including JAMA, Lancet and American Journal of Clinical Nutrition.