Using Wegovy after 6 weeks of opening: what the guidance actually says

Why the 6-week limit exists and what happens if you go past it

A question our prescribers hear most weeks is whether it is safe to use the last injection from a pen that has been sitting in the fridge for slightly longer than six weeks. The short answer is no. The 6-week in-use shelf life for Wegovy is not a conservative estimate left over from cautious labelling, it reflects real stability data for semaglutide once the pen has been activated. After that window, the medicine may have degraded, meaning the dose you inject could be weaker than intended, and you would have no way of knowing. The NHS medicines information for semaglutide confirms that once a pen is in use, it should be discarded after six weeks. This limit holds whether the pen has been stored in the fridge at 2–8°C or kept at room temperature below 30°C during that period. Our guide to Wegovy shelf life after opening sets out the precise room-temperature storage window and further handling details, though you should always follow the Patient Information Leaflet that comes with your pen rather than general guidance you find online. Keeping a note of the date you first used each pen is a simple habit that removes the uncertainty entirely.

The decision: discard and continue, or has a gap opened up?

Once you have established that a pen is past six weeks, you face a practical fork. If your injection schedule has stayed broadly on track and you are simply disposing of a pen that ran out before you could use the last dose, you can open your next pen and continue your prescribed regimen. The issue is different if the six-week limit has expired because you missed several weekly injections, perhaps due to illness, travel, or supply. In that case, a gap in treatment has also occurred, and the two problems layer on top of each other. People who have paused semaglutide for more than a few weeks sometimes find that gastrointestinal side effects return when they resume, because their system has lost the tolerance built up during titration. Our guide to restarting Wegovy after a six-week break covers exactly this scenario, including when stepping back down the dose schedule is worth discussing with your prescriber. What is true in both cases is that a prescriber, not the leftover pen, is your reference point for what to do next.

Dose and pen management to avoid reaching 6 weeks with doses left

The most common reason people arrive at the end of week six with injections still in the pen is a missed dose early in the cycle that was never made up. Wegovy pens are supplied as single-injection devices rather than multi-dose vials, so this is less likely than with some other formats, but it still happens. If you realise you have missed a weekly dose, the guidance is to take it as soon as you remember, provided the next scheduled injection is more than three days away. If your next dose is within three days, skip the missed one and carry on as normal. Never take two doses to compensate. Understanding how this plays out in practice is covered in our overview of the first month on Wegovy, which also explains what changes to expect as the dose increases. Cost is a practical factor here too: discarding a pen with doses remaining is frustrating, particularly at current private prescription prices. Our breakdown of Wegovy costs in the UK puts the price landscape in context and explains what a legitimate private prescription should include. Precise adherence to your weekly schedule is the simplest way to avoid waste.

When to speak to a prescriber rather than deciding alone

There are several situations where the right move is not to simply open the next pen and continue. If you have had a gap of more than four weeks due to supply issues, side effects, or another reason, a clinical review before restarting is sensible. The same applies if you are unsure whether your current dose is still appropriate, if you have started a new medication in the interim, or if your circumstances have changed significantly since your last review. The wegovy consultation process at nume gives you access to a GPhC-registered prescriber who reviews your case personally before any prescription is issued. A prescriber can confirm whether you should continue at your existing dose or whether a period of re-titration would make the restart safer and more comfortable. For broader context on semaglutide and how it works, the semaglutide information page covers the mechanism and licensed indications in plain language. You can also read through our frequently asked questions for practical answers to the most common prescribing queries.