Medicine Jar by Paul McCartney delves into themes of addiction and self-destruction. The song addresses the pitfalls of substance abuse, illustrated by the metaphor of a 'medicine jar' representing drugs or alcohol. It serves as a cautionary tale, emphasizing the physical and emotional toll that addiction takes. Poignant moments include lines that describe the urgent need for help and the descending spiral of dependency. The lyrics underscore the importance of recognizing one's struggles and seeking support before it's too late.