My Wegovy shot leaked out — what does it mean and what should I do?

What the Wegovy SmPC and clinical guidance actually say about leakage

The Wegovy Summary of Product Characteristics (SmPC), available via the electronic Medicines Compendium, describes the correct injection technique in precise detail, and it is worth reading it once, because the pen's design catches most people out the same way. The dose is released when you press the injection button; the plunger continues moving for several seconds after that click. If the pen is pulled away before the plunger finishes its travel, the remaining liquid exits the needle tip rather than the tissue. That looks dramatic. It is not the same as the injection failing entirely.

A wet patch on the skin, or a bead of clear or slightly cloudy liquid, most commonly traces back to early pen withdrawal. The NHS guidance on weight-management injections notes that subcutaneous semaglutide should be injected slowly and the pen held still; the six-second hold is not a formality. Redness, a tiny blood spot, or mild stinging at the site are all normal injection-site reactions recorded in trial data and do not indicate leakage of the dose itself.

Where leakage is more significant (you see fluid running from the needle during the injection, or the skin surface is visibly wet before you remove the pen) the picture is less clear-cut. Subcutaneous tissue absorbs semaglutide quickly, but if a substantial volume exited the needle before reaching the skin, some dose may genuinely be lost. This is the scenario your prescriber needs to know about.

The difference between an injection-site reaction and an actual dose loss

A question our prescribers hear most weeks is: "I saw liquid come out, did I waste the whole dose?" The honest answer is that it depends on when and where the liquid appeared. During injection, before the click, is the concerning scenario. After the six-second hold, on pen removal, is almost always residual fluid from the needle channel, normal, expected, and not a meaningful dose loss.

Blood at the site is similarly misread. A capillary nick causes a small red bead; this does not mean the semaglutide leaked out alongside it. The medicine is absorbed via the subcutaneous fat layer, not through the bloodstream at the injection site. A bruise the following day is a sign of that capillary catch, not of anything going wrong with the medicine itself.

Technique problems that genuinely do cause partial dose loss include: removing the pen too quickly, pressing the button while the needle is still entering the skin (so some liquid escapes to the surface before full insertion), and using a needle that is bent or blocked. If you are reusing needles (which the SmPC advises against) blockage is more likely. Changing to a fresh needle for every injection removes that variable; replacement pen needles are available if you need a fresh supply.

If the dose consistently looks as though it is leaking, reviewing your injection sites may help. Rotating between the abdomen, outer thigh, and upper arm (and avoiding areas of hardened skin or recent bruising) improves absorption and reduces surface leakage. For a full walkthrough of the correct technique, the step-by-step guide to taking your Wegovy shot covers each stage in detail.

What to do after a Wegovy shot has leaked, and what not to do

Do not inject a second dose. This is the consistent clinical advice: the risk of doubling up on a weekly GLP-1 medicine outweighs the benefit of correcting a partial loss, and self-adjusting doses without prescriber input is not safe. The NHS semaglutide medicines page is clear that missed or compromised doses should be handled with prescriber guidance, not self-corrected.

If you are confident the leak was minor (a post-removal bead, a small skin wet patch), continue your schedule as normal and note what happened. If you are concerned the leak was substantial, contact your prescriber or pharmacy the same day where possible. At nume, our clinical team is available for aftercare seven days a week, so patients are never left managing this alone.

Document what happened: which dose strength, which injection site, what you saw and when. That detail helps a prescriber give you a specific, useful answer rather than a generic one. If you are finding the pen consistently difficult to use (perhaps a dose has leaked before, or you are unsure whether the pen functioned correctly from the start) there is more detail on what a partial leak during an injection typically means in practice, and separately on how to read the signs of leakage at the injection site itself.

Storage also matters. Wegovy must be kept refrigerated at 2–8°C; if a pen has been left at room temperature beyond the window stated in the leaflet, or has been frozen, the formulation may be compromised before it even reaches the needle. If you are uncertain whether a pen has been stored correctly, do not use it. There is a separate guide on what happens if Wegovy has been frozen if that applies to your situation.

Missing a dose entirely is a different scenario from a partial leak, and the guidance differs accordingly. If you end up skipping the week because you are unsure what happened, the page on what to do after a missed Wegovy dose explains the timing rules your prescriber follows. And if you are still building familiarity with injectable weight-loss treatments more broadly, the Wegovy treatment overview sets out how the medicine is used within a supervised clinical programme.