Definition: A temperature excursion is a short time a medicine spends outside its normal storage range. When a label says "excursions permitted to 15-30 °C", it means brief swings to those temperatures are allowed for a product normally kept at controlled room temperature (20 to 25 °C). Going beyond the stated limits is not covered by the label.
The word appears in section 16 (How Supplied, Storage and Handling) of many tablet labels. Januvia, Actos, Tradjenta and the other diabetes pills on this site use "excursions permitted to 15-30 °C (59-86 °F)". The Gvoke glucagon label allows "brief excursions" between 59 °F and 86 °F and adds that it is not refrigerated or frozen. These labels do not say how many hours an excursion may last.
Refrigerated medicines rarely use the word. Instead they give a room-temperature allowance with a day count, such as Lantus at up to 86 °F for 28 days. Time outside the fridge counts against that allowance, and some labels say a product cannot go back in the fridge once it has been out. Heat above the stated limit and freezing are the two things most fridge labels rule out.
Reading an excursion line
An excursion is easy to forget a week later. A short note with the date, the rough temperature and how long it lasted gives a pharmacist something concrete to judge, and links any change in how a medicine works to a real event.
Read more on Dose Track: Left out of the fridge · Traveling with injectables · How to store glucagon