Few drugs have reshaped the world like penicillin. In this episode, we trace its origin story—from Alexander Fleming’s serendipitous discovery in 1928 to the urgent push during World War II that turned moldy lab dishes into mass-produced medicine. We spotlight the critical roles of Florey, Chain, and Heatley, whose tireless work at Oxford transformed penicillin into a viable therapeutic agent. With the help of Pfizer's deep-tank fermentation breakthroughs, penicillin became the prototype for modern antibiotics and a game changer in treating deadly bacterial infections.

But penicillin’s story is more than just medical triumph. We explore its regulatory journey, the global decision to avoid early patenting, and how the antibiotic revolution redefined public health. From its economic ripple effects to its cultural status as a miracle drug, we also examine the complications—including allergic reactions, challenges in manufacturing, and, most importantly, the emergence of antibiotic resistance. Penicillin saved millions—but it also set the stage for the modern antibiotic era’s toughest question: how do we preserve the power of such wonder drugs in a world rapidly adapting to resist them?