Which Pokémon anime episode caused a mass illness incident in Japan in 1997?

“Dennō Senshi Porygon” caused a mass illness incident in Japan in 1997.

The episode aired on December 16, 1997, during the original Pokémon anime series. A scene involving rapidly alternating red and blue flashes triggered seizures and other reported symptoms among viewers, leading hundreds of people to receive medical attention or be taken to hospitals.

The event became known internationally as the Pokémon shock. Japanese broadcasters suspended the series temporarily, and the incident prompted changes in television production and broadcast safety practices. The anime later returned after a review period.

Although Porygon appears in the episode, the flashing sequence was produced by attacks involving Pikachu. Porygon was subsequently removed from most later anime appearances, which is why viewers often incorrectly attribute the direct visual cause to Porygon itself.