Canned juice can be kept in the pantry for up to 18 months. Onceopened, it can be stored in a container in the fridge for 3-4 days. Onceopened, it can be stored in a container in the fridge for 3. One source states that Keflex (cephalexin) suspension can be left out at room temperature for up to 24 hours with no effect on stability. Room temperature is defined as 68 to 77 °F. Room temperature is defined as 68 to 77 °F. Can liquid cephalexin be used after 30 days of being mixed and refrigerated? It shouldn't be (the shelf life is around 14 days refrigerated), but it probably won't kill you. It may be less effective. There's no need. The drug is stable at room temperature, and in general antibiotics should be taken only when and for how long they are prescribed. keflex, cephalexin, potency: The cephalexin will start to break down in time since it was not kept refrigerated. It should be replaced if possible. Giving one dose. It should be replaced if possible. Giving one dose. Cephalexin - How long can you have keflex liquid out of refrigerator? If it is out for 8 hours in? Asked 18 Mar 2016 by tricia1989 Updated 18 March 2016 Cephalexin comes as a capsule, tablet, and suspension (liquid) to take by mouth. It is usually taken with or without food every 6 or 12 hours for 7 to 14 days, depending on the condition being treated. The shelf life of cephalexin capsules and tablets is three years when stored correctly, according to the electronic Medicines Compendium. The storage containers must remain tightly closed and must be stored at temperatures below 86 F. Cephalexin for Dogs. Cephalexin is an antibiotic that’s available in both capsule and liquid form. It can be used to treat a variety of infections throughout a dog’s body. Out of the medications reviewed which can be stored at room temperature, it resulted that 1039 medications should be stored below 25°C, 414 should be stored below 30°C, 4 medications should be stored below 37°C and 334 have no special temperature storage.