Which Pokémon anime episode caused a nationwide health incident in Japan in 1997?

Dennō Senshi Porygon caused a nationwide health incident in Japan in 1997.

The episode, also known as Electric Soldier Porygon, was broadcast on December 16, 1997, as episode 38 of the first Pokémon anime season. Rapid red and blue flashing effects during an explosion triggered photosensitive seizures and other symptoms in many viewers, especially children.

More than 600 people were taken to hospitals after the broadcast, and the anime entered a four-month hiatus. The episode was removed from rotation and was never broadcast again in Japan or internationally. Porygon itself was not responsible for the flashing sequence, but the character became strongly associated with the incident in public discussion.

The event led Japanese broadcasters to adopt stricter precautions for animated flashing effects. It also affected plans for the anime’s overseas localization. The episode’s title is often shortened incorrectly to Porygon, but the full Japanese title is Dennō Senshi Porygon.