Prozac and the SSRI revolution (1988)
Eli Lilly launched fluoxetine (Prozac), the first selective serotonin reuptake inhibitor (SSRI), for depression. Within months it outsold every existing antidepressant. Doctors began prescribing it not just for major depression but for obsessive-compulsive disorder, bulimia, panic disorder, and anxiety — conditions for which it had not yet been formally approved.
Prozac became a cultural phenomenon, selling $2.7 billion annually at its peak. Millions of people who would not have sought treatment for depression began taking medication.
SSRIs eventually received FDA approvals for multiple conditions beyond depression, validating the off-label use that preceded formal regulatory action. The class demonstrated that a drug targeting one brain mechanism can treat a range of disorders sharing that underlying biology.
GLP-1 drugs are following a strikingly similar trajectory: approved for one condition (diabetes), then a second (obesity), now showing broad effects on a third category (addiction) that shares underlying brain reward circuitry. The SSRI precedent suggests off-label prescribing may outpace formal approvals.