A total of 685 viewers were taken to hospitals after the 1997 Pokémon episode “Dennō Senshi Porygon.”
The episode aired in Japan on December 16, 1997. A sequence involving rapidly alternating red and blue flashes triggered reports of visual symptoms, headaches, dizziness, and seizures among viewers. Emergency services transported hundreds of people to hospitals.
The incident became known as the Pokémon shock. Japanese broadcasters and production companies investigated the episode, and the anime was temporarily taken off the air while safety procedures were reviewed. The event also received extensive international media coverage.
Despite the episode’s title, Pikachu—not Porygon—created the flashing effect during the scene. Porygon and its evolutions were subsequently absent from later mainline anime appearances, although the Pokémon remained part of the wider franchise.