How to Prime Your Wegovy Pen Before the First Injection

You've taken the pen from the fridge, here's what happens next

Picture the moment: pen in hand, needle packet open on the worktop, a little nervous about getting it right. That is exactly where this guide starts. The Wegovy pre-filled pen comes ready to use, but before the very first injection from any new pen you need to prime it. Priming pushes a tiny amount of semaglutide solution through the needle to expel any air sitting in the tip, and to confirm the pen's drive mechanism is working.

First, wash your hands thoroughly. Remove the pen cap and check the liquid through the window, it should be clear and colourless. If it looks cloudy, discoloured or contains particles, do not use it; contact your pharmacy. Next, attach a new needle by peeling off the paper seal, pressing the needle straight onto the pen tip and turning clockwise until it is firm. Remove the outer needle cap (keep it, you'll need it after the injection) and then pull off the inner needle cap and discard it.

Now turn the dose selector to the priming symbol, which on the Wegovy pen looks like two drops. Point the needle upward and tap the pen gently with your finger a few times to encourage any air bubbles toward the tip. If you want a full walkthrough of each step in sequence, our guide covering how to prime the Wegovy pen without a needle attached also explains the underlying mechanism clearly. Hold the pen upright, press and hold the injection button, and watch the needle tip. A small drop of liquid should appear. That drop is your confirmation. Whether priming is always compulsory is a question our prescribers hear regularly, the short answer is yes, for every new pen. Once you see the drop, you are ready to select your prescribed dose and inject.

Always refer to the Patient Information Leaflet that comes with your pen for the manufacturer's exact instructions, the NHS semaglutide medicines page also summarises how to use the pen correctly.

Why no drop appeared, and how to prime a Wegovy pen a second time

Sometimes the drop does not appear first time. This usually means the needle is not seated firmly enough, or there is more air in the line than one press cleared. Do not inject without confirming the prime. Instead, repeat the process: keep the pen pointing upward, dial back to the priming symbol and press the button again. One repeat attempt is normal. Priming the pen twice does not waste a meaningful amount of medicine and is far safer than injecting an air-locked dose.

If after two attempts you still see nothing at the needle tip, check a few things before assuming the pen is faulty. Is the needle on straight? A cross-threaded needle will block flow. Did you remove the inner cap as well as the outer one? It is an easy step to miss under pressure. Is the pen actually a new one from the fridge, not a pen that was already used and is now empty? If everything checks out and the pen still won't prime, call your pharmacy or prescriber rather than pushing ahead.

One practical note on timing: if your new pen arrives on a Friday and you're due your weekly injection over the weekend, do not leave troubleshooting until Sunday evening. Pharmacies and clinical teams are harder to reach then. At nume, prescriber support is available seven days a week precisely for moments like this, reach us through our support page if you need guidance.

After a successful prime, store any partially used pens back in the fridge or in a cool place per the leaflet instructions. Used needles go straight into a proper sharps container, never the household bin.

Attaching a new needle correctly, and why it changes the priming outcome

The needle is not just a delivery tool; it is part of the prime. A needle that is loose, damaged or reused will give a false result, either no drop, or a misleading trickle that doesn't reflect what will actually reach your tissue. Attaching a fresh needle each time before you prime is not optional. Reusing needles blunts the tip, increases injection discomfort, and risks partial blockages that a prime check cannot always detect.

The mechanics are simple: peel the paper tab off the needle, hold it straight and push it firmly onto the pen connector, then twist clockwise. Crooked attachment is the single most common reason new users get a failed prime on the first attempt. It is worth slowing down for those five seconds.

If you prefer not to handle the needle at all before attaching, the outer cap holds the needle while you connect it. You only expose the actual point when you remove the inner cap just before the injection. This technique can help if you are anxious about needles. Our clinical team can talk through injection technique with you if that concern is holding things back.

For a broader picture of how Wegovy works as a treatment and what the licensed doses look like, the Wegovy overview page covers the full context. And if you are thinking about where to get your prescription, this guide on sourcing Wegovy safely in the UK explains the legal supply route and what to look for in a registered pharmacy.

After the prime: injection sites, rotation and what a normal first dose feels like

Once the pen is primed and your dose is dialled, choose one of three injection sites: the abdomen (at least 5 cm from the navel), the front of the thigh, or the upper arm. Clean the skin with an alcohol swab and let it dry fully, wet skin stings more. Insert the needle at a 90-degree angle, press the injection button and hold it in for six seconds before withdrawing. That six-second hold matters; releasing too early can mean not all the medicine has been delivered.

Rotate your site each week. Injecting repeatedly into the same spot builds up tissue changes that affect absorption. Keep a simple note on your phone of where you injected last, it takes two seconds and prevents months of avoidable irritation.

The first dose (0.25 mg, the starting strength) is designed to let your system adjust, so most people notice mild nausea at most. Any stomach upset typically eases within a few days. If you experience severe or persistent abdominal pain, especially pain that spreads to your back, seek medical attention promptly, the MHRA Yellow Card scheme is also there for reporting unexpected side effects. Questions about other GLP-1 injection options are covered on the semaglutide and GLP-1 overview page.