Left Your Wegovy Out Overnight? Here Is What Matters

Step 1: Check the leaflet figure before you do anything else

Every Wegovy pack includes a Patient Information Leaflet. Open it now and find the storage section. It states the maximum number of hours a pen may be kept at room temperature (below a specified temperature ceiling) before it must be discarded. That figure is the single most important number in this situation, and it is the one we will not reproduce here, because the MHRA-approved leaflet is the definitive reference and yours is already in your hands.

Once you have that number, work out honestly how long the pen was out. An overnight absence from the fridge is typically eight to ten hours, but if you left it out before bed and found it after a slow morning, it could be twelve or more. Be honest with yourself about the timeline, a rough guess in your favour is not worth the risk. The NHS medicines page for semaglutide also sets out the key storage rules in plain language if you want a quick cross-reference.

One practical habit that takes less than a minute: before you inject each week, glance at the pen's appearance, the solution should be clear and colourless to pale yellow, with no particles. If it looks cloudy or discoloured after a temperature excursion, do not use it regardless of the time elapsed.

Step 2: Understand what the room temperature actually matters

The room-temperature limit in the leaflet assumes reasonably normal indoor temperatures, not a warm kitchen in July or a car left in the sun. If the pen spent the night in an unusually warm room, near a radiator, or in a bag left in a car, the effective risk is higher than a cool bedroom at night. Storage temperature and duration together determine whether the semaglutide has degraded, the time limit assumes a temperature ceiling, and both conditions matter.

A pen that has been out for five hours in a 30°C kitchen is a different situation from one left on a cool hallway shelf for nine hours. Think about the conditions, not just the clock. If there is any real doubt, your prescribing team can advise. At nume, a named prescriber reviews every clinical question, you can reach the team through our aftercare line, which operates seven days a week.

The broader context of your Wegovy treatment (including which dose you are on and how your body has responded) is something our clinical team can discuss with you. You can read more about the titration schedule and what each stage involves on our guide to Wegovy dose increments.

Step 3: Make the call, use it, discard it, or ask first

If the pen was out for less time than the leaflet's stated limit, in a cool room, and looks normal: it is likely still within specification. You can use it at your next scheduled injection time. Do not inject early to compensate for the uncertainty, timing your doses correctly is part of how the medicine works, and your overview of Wegovy explains the once-weekly schedule clearly.

If the pen exceeded the storage window, or if the room was warm and you are not confident, the safer choice is to discard it and contact your prescribing team. Losing one pen is frustrating. Using degraded semaglutide risks both reduced effectiveness and unknown safety implications, neither is a good outcome for your treatment. Our Wegovy cost and pricing page has context on what replacement treatment involves.

If your pen was frozen at any point, discard it without exception. Freezing destroys the formulation regardless of how briefly it happened, and a frozen-then-thawed pen will not look visibly different. There is no reliable way to tell by looking.

What happens to your injection schedule now

A delayed or missed dose does not mean you restart from the beginning. Semaglutide has a long half-life, and the guidance in your leaflet covers what to do if you miss a weekly injection, the general principle is to take the dose as soon as you remember if it is within a defined window, or to skip to your next scheduled day if it is not. Your leaflet gives the exact timing; follow that, and check with your prescriber if you are uncertain.

Missing a single dose rarely causes major disruption to progress, though some people notice a temporary return of appetite. This is a normal pharmacological response, not a sign the medicine has stopped working. If you experience any side effects that concern you after restarting (whether digestive discomfort or anything else) our clinical team is available to advise. Some patients also notice changes in how exercise feels during and after doses; our guide on exercising with Wegovy covers what is commonly reported. And if you develop any pain in your left side or abdomen around injection time, our page on left-side pain and Wegovy sets out when to seek medical attention promptly, and our guide to pain specifically under the left rib with Wegovy explains what that more localised symptom can sometimes indicate.

If your Wegovy journey is just getting started and you would like to understand whether this treatment is right for you, check your eligibility with our prescribers, consultations are free and reviewed the same day.