Wegovy pen misfire: what actually happened and what to do next

The scene: you pressed the button and nothing felt right

Picture it: you've cleaned the site, attached a fresh needle, pinched the skin as you've done before, and pressed the purple start button firmly. But there was no second click (or the click came immediately, before you'd counted ten seconds) or the pen just felt different. Now you're holding it, wondering whether to throw it away or try again.

The first thing to do is stop and check the dose counter. On a Wegovy pen, the counter should have moved to zero after a successful injection. If it still shows your dose number, the medicine almost certainly didn't deliver. If it reads zero, the dose very likely went in even if you didn't feel it, semaglutide injections are designed to be relatively painless, and the absence of sensation isn't a sign of failure.

Don't press the button again. Don't try a second injection from the same pen at the same site. Put the pen down, note the counter reading, and work through the checklist below before contacting your pharmacist or prescriber. The full guide to the Wegovy pen has detail on each part of the device if you want to orientate yourself.

Why Wegovy pens misfire, the most common causes

Most pen failures come down to one of four things, and understanding which one matters for knowing what to do next.

The needle wasn't attached correctly. If the needle wasn't screwed on firmly, medicine can leak back out of the pen rather than entering the tissue. You may see a drop of liquid on your skin or on the needle tip. This is the most common cause of a failed injection, and it's why the instructions specify priming the pen after attaching the needle, a small dot of medicine at the needle tip confirms the pathway is clear. The dose-specific guide for your strength covers the priming step precisely.

The pen wasn't held at the skin long enough. Wegovy's instructions ask you to hold the pen in place for at least ten seconds after the first click, keeping the button pressed until the counter reaches zero. Removing it early is one of the easier mistakes to make when you're nervous or rushed, and on a busy Monday morning, with the school run looming, it happens more than people admit.

The injection angle was too shallow. The pen should be held at 90 degrees to the skin, straight on, not at an angle. Too shallow and the needle tip may not clear the skin layer to reach subcutaneous tissue. Abdomen, outer thigh, and upper arm are the approved sites per the Patient Information Leaflet; fatty tissue at 90 degrees gives the best result.

The pen itself was faulty. Genuine mechanical faults are rare but documented. If the counter moved partially or the button stuck, retain the pen and contact your pharmacist. Don't discard it, a pharmacist may be able to inspect it and support a replacement request with the supplier. You can also report device defects to the MHRA via the Yellow Card scheme.

Partial doses, wasted medicine, and what the guidance says about missed injections

If the counter didn't reach zero, treat it as a partial or missed dose. The published guidance for a missed Wegovy injection is clear: if you realise within five days of your scheduled injection day, take it as soon as you remember and then resume your usual day. If more than five days have passed, skip that dose entirely and carry on with the next scheduled one. Never take two doses within five days of each other.

That same logic applies here. A misfired pen that delivered nothing or very little is effectively a missed dose. Follow the same window rule, and if you're unsure where you stand (particularly if you're mid-titration or just starting at a new strength) speak to a prescriber. Changing the timing or repeating the injection without advice isn't worth the risk. Our missed Wegovy injection page sets out the full five-day rule in detail.

One note on the medicine itself: semaglutide is temperature-sensitive. Pens should be stored in the fridge between 2°C and 8°C; a pen that's been left in a warm car or a hot bathroom cabinet may look intact but perform less reliably. If you want to understand how volume and fill levels relate to correct storage and use, the guide to Wegovy pen ml covers what to expect inside each device. Always refer to your Patient Information Leaflet for the exact conditions, the NHS semaglutide medicines page covers storage basics alongside side effects and what to watch for.

Going forward: reducing the chance of it happening again

Most people who've had a misfire find a specific step they'd been doing slightly wrong, adjust it, and never have another. A few practical habits make a real difference.

Change the needle before every injection, a used or bent needle increases resistance and can affect delivery. Keeping a stock of compatible needles means you won't be tempted to reuse one when supplies run low. Clean the injection site with an alcohol swab and let it dry fully before you start; wet skin can affect pen grip and injection angle. Rotate sites each week so you're not repeatedly using the same small patch of tissue, which can affect absorption over time.

If pens are consistently performing strangely or you're finding the technique difficult to manage, it's worth raising with a prescriber at your next clinical review. Technique questions are entirely normal (a question our prescribers hear regularly) and getting it right matters more than any embarrassment about asking. For broader context on Wegovy and how treatment works, the Wegovy overview page is a good place to start, and if you're weighing up how private treatment fits into your situation, the Wegovy cost page covers what a legitimate private prescription typically involves.

If you're not yet on treatment but have been looking into Wegovy, semaglutide is a prescription medicine that requires clinical assessment before it can be dispensed. Check your eligibility through a free consultation with our prescribers.