Progressive Perfect Probiotics are formulated to easily withstand elevated temperatures for modest amounts of time (up to a few weeks) without losing their potency. In addition, it is important to note that our probiotics are guaranteed to contain the label claim for potency at time of expiry. This accounts for shipping times and takes into account modest losses as a result of temperature variances during the shelf life of the product. For best results, refrigerate all Progressive Probiotics for long term storage. If refrigeration is not available, please store your product tightly sealed against moisture and away from heat.