In this episode, Jam recounts a humorous yet enlightening story of accidentally taking a dog-sized dose of Benadryl and the sleepy consequences that followed. Melissa, a chemist, dives deep into the chemistry of antihistamines, explaining the difference between first-generation (drowsy) and second-generation (non-drowsy) antihistamines. The episode covers the role of histamine in the body's allergic reactions and how different antihistamines interact with histamine receptors. Melissa elucidates the chemical structures of these medicines and how their polarity affects their ability to cross the blood-brain barrier, ultimately influencing whether they cause drowsiness.