Certainly can be affected adversely by temperature. Drugs are designed to be stored at "room temperature". Unless they are well sealed, there is some risk from humidity and other moisture sources.<br><br>I would recommend against both tylenol and ibuprofen, favoring the later as it is more effective for pain, as an antipyretic, and has anti-inflammatory effects than acetaminophen. Likewise, I would ditch the tylenol flu. <br><br>Just an opinion.<br><br>