Penicillin became commercially available in the United States in 1945. The date marked the transition from a scarce wartime medicine, distributed mainly through military and selected hospital channels, to a drug that civilians could obtain more broadly.
American production had expanded dramatically during World War II. Government agencies coordinated research, factories, and allocation, while companies including Pfizer, Merck, Squibb, and Lederle developed industrial fermentation. Production rose from roughly 21 billion units in 1943 to an estimated 6,852 billion units in 1945.
The United States made penicillin available to the general public on 15 March 1945, and it was commercially available by the end of that year. A common mix-up is confusing this date with the first successful treatments: Cecil Paine used crude penicillin clinically in 1930, while the first U.S.-made penicillin treatment occurred in 1942. Fleming’s 1928 discovery was therefore only the beginning; purification and mass production took more than a decade.