Your Wegovy pen looks broken — here's what to check first

The moment the pen doesn't fire: what's most likely happening

You've pressed the button. Nothing happened, or something felt off. The most probable explanation isn't a faulty pen, it's a needle issue. Needles for Wegovy injections should be attached immediately before use and removed straight after; a needle left on from a previous week can block, and a new needle that wasn't pushed on firmly won't seat properly. One quick check: detach the needle, attach a fresh one from your supply, and try again at a new injection site.

If the pen still doesn't respond, look at the dose window. On Wegovy's pre-filled pen the small window shows the remaining dose indicator. If it has moved to the end position, the pen has already delivered its dose, sometimes silently, or during a hesitant first attempt. The Wegovy pen's mechanism is designed so the dose is released the moment the button depresses fully against skin, which can feel less dramatic than people expect.

A practical habit worth building: before each injection, hold the pen up to the light and check the liquid. It should be clear and colourless. Cloudiness, particles, or visible discolouration mean you should not use that pen. Set it aside and contact your pharmacy. This takes about fifteen seconds and is the most useful single check you can do.

The NHS medicines page for semaglutide and the full Patient Information Leaflet both direct you to contact your pharmacist or prescriber for any doubts about the pen or the injection, that remains the right call if checks don't resolve the problem.

Storage damage and temperature: the silent reason pens fail

Wegovy pens must be refrigerated between 2°C and 8°C. A pen that has been frozen, left in a hot car, or kept in a bag pocket against a warm body for longer than the leaflet permits may look fine but behave abnormally, the liquid can become slightly viscous, and in frozen pens the mechanism can be impaired. The Patient Information Leaflet states the exact room-temperature window; never go by memory or assume the window from a different semaglutide product applies here.

If you think the pen was exposed to extremes of temperature, don't use it. The risk isn't just that it won't work, it's that compromised storage can affect the medicine itself. Contact the pharmacy that dispensed it.

One scenario worth knowing: taking a pen abroad or to a holiday cottage without a travel case is a frequent trigger for this problem. A small insulated pouch keeps the pen within range during transit. If you've noticed your device looking different from usual, it's worth reading about what a brown Wegovy pen indicates, including what the pre-filled cartridge contains, which is useful background if you're planning ahead for travel.

If you're unsure whether your pen was within the correct storage window, the MHRA's Yellow Card service at yellowcard.mhra.gov.uk allows you to report a suspected product defect, this matters for medicines safety data, and the report helps regulators track manufacturing or supply chain issues.

What counts as a genuinely faulty pen, and what to do about it

Manufacturing faults in Wegovy pens are uncommon but real. Signs that point to an actual defect rather than a user or storage issue: the plunger moves but no resistance is felt and the dose window doesn't change; the pen body is cracked or the seal is visibly broken; the dose indicator is already at the end position on a pen you haven't used. In those cases, set the pen aside in a sharps container (don't discard it in general waste) and contact your pharmacy.

Do not inject a second dose from a spare pen to make up for a suspected missed one. Doubling up on semaglutide in a short window significantly increases the risk of nausea and other gastrointestinal side effects, and the right dose timing is your prescriber's call, not a self-directed fix. Your prescriber can advise whether to wait for the next scheduled injection day or adjust the timing slightly.

If you're on a fixed supply and a pen is wasted through no fault of yours, a GPhC-registered pharmacy should be your first call, document what happened clearly when you contact them. You can find out more about what a regulated dispensing service looks like via the about us page, or read the broader context of how Wegovy works as a treatment so you're better placed to have that conversation with a clinician.

If ongoing questions about your treatment are piling up, our free consultation connects you with a GPhC-registered prescriber who can review your situation the same day.

Pen broken mid-course: does it affect your progress?

Missing one dose because of a faulty pen is unlikely to derail treatment, but it's not nothing. Semaglutide works by maintaining steady blood levels week on week; a gap can mean the next dose feels more like a first dose, nausea may return briefly. That's more an inconvenience than a harm, and most people find it settles quickly.

The more important question is whether you're at a dose that's working for you. If you're early in the titration schedule and a pen problem causes a longer delay, speak to your prescriber before the next injection rather than after. If you're starting out on the lowest strength and want to understand what you've been given, our page covering the Wegovy 1 pen explains what that first titration dose involves, and if you'd like to know more about how volume and markings work across devices, our guide to the Wegovy 1 ml pen covers what's inside each cartridge, which is useful background if you're weighing your options.

Pen failures mid-course are also worth flagging to the prescribing service, not just to sort out the immediate supply question, but because a pattern of faulty pens from the same batch is the kind of thing a GPhC-registered pharmacy needs to know about. Good aftercare means that kind of feedback actually reaches someone who can act on it. If you want to understand how dosage volume relates to what you're injecting each week, our page on the Wegovy pen ml breakdown explains how the fill and dose increments are structured across the titration course.