Wegovy pen malfunction and replacement: your questions answered

What counts as a Wegovy pen malfunction?

A pen malfunction is any failure of the device that prevents a complete, confirmed dose being delivered. The most common reports involve the needle not extending properly, the plunger failing to depress fully, a cracked or broken outer casing, and the pen locking prematurely before injection is finished. Leaking medication around the needle hub is also a fault, as is a dose counter that does not move after you press the button.

What a malfunction is not: a small air bubble at the tip before injection (normal), a tiny drop of liquid after the needle is removed (also normal), or a pen that has been stored incorrectly and is now unusable through no device defect. That last scenario is a different problem (temperature damage) and is worth raising with your pharmacy separately. If you are unsure whether what happened counts as a fault, our guide to how the Wegovy pen works walks through what a successful injection looks and feels like.

Device failures should be reported to the MHRA via the Yellow Card scheme, which covers medical devices as well as medicines. This is genuinely useful, the MHRA uses Yellow Card data to track whether a particular batch or device component is producing more failures than expected.

What should you do immediately after a pen fails to inject?

First: do not attempt a second press with the same pen or try to reset it. Pre-filled GLP-1 pens are not designed to be restarted mid-injection, and forcing the mechanism risks an uncontrolled dose or a needle-stick injury. Place the pen, needle still attached, into a sharps container straight away, do not recap the needle by hand.

A question our prescribers hear most weeks is whether to try again with a new needle on the same pen body. The answer is no. Once a Wegovy pen has misfired, the integrity of the remaining medication and the dose-counter mechanism cannot be confirmed, and our guidance on Wegovy needle replacement explains why attaching a fresh needle to a pen that has already failed is not a safe workaround. The whole pen is out of use.

Contact your dispensing pharmacy the same day. Have the pen's batch number and expiry date to hand, these are printed on the label and on the outer carton. Your pharmacy will log the fault, advise on the missed-dose timing window, and initiate a replacement request with Novo Nordisk where appropriate. For patients sourcing Wegovy through nume, our aftercare team is available seven days a week, reach us here.

On missed-dose timing: the Wegovy Patient Information Leaflet (available via the electronic Medicines Compendium) sets out the exact rules for whether to take a replacement dose within a certain number of days or to wait for the next scheduled day. Follow that guidance and confirm with your prescriber.

How does pen replacement actually work?

Replacement routes depend on where you sourced the treatment. For privately dispensed Wegovy, the pharmacy that dispensed your pen is responsible for logging the device failure and liaising with Novo Nordisk's UK medical information line. Novo Nordisk does have a faulty-device process, but it runs through the dispensing pharmacy, patients cannot access a free replacement by contacting the manufacturer directly.

What replacement looks like in practice: the pharmacy will typically ask you to retain the faulty pen (in your sharps container if possible, or in the original packaging) so the batch can be investigated. A replacement pen requires a valid prescription, so your prescriber will need to confirm the replacement is appropriate, this is not an automatic swap. The full process for a defective Wegovy pen replacement is covered in more detail if you need the step-by-step.

If you sourced your Wegovy from a pharmacy that is no longer reachable or that you now have doubts about, that is a separate concern. Any legitimate online pharmacy dispensing a prescription-only medicine is registered on the GPhC register, you can check at pharmacyregulation.org. Pharmacies operating outside the licensed supply chain cannot guarantee device quality or offer a genuine replacement pathway.

Does a faulty pen affect your next injection or titration schedule?

It can, and this is worth discussing with your prescriber rather than assuming. If the failed pen was your last at a particular dose and you are due to move to the next strength, your prescriber needs to decide whether to send a replacement at the current dose or proceed to the higher one, that judgement depends on how well you have tolerated treatment so far and how many weeks of the current dose you have actually completed.

For context on what the licensed titration schedule involves, the Wegovy treatment overview covers the progression from the 0.25mg starting dose through to the higher maintenance doses. For a broader look at how injection-based weight-loss treatments compare, our guide to weight-loss injections is a useful reference.

If you are paying privately and want to understand the cost implications of a replacement pen, our Wegovy price comparison page sets out what legitimate private pricing typically includes and what it does not. A properly run private service factors aftercare (including device failure support) into the overall price rather than treating it as an extra.

If you are considering starting treatment or are mid-treatment and have questions about your eligibility, our prescribers review every case individually. Check your eligibility and start your free consultation.