Which Pokémon episode was withdrawn after causing seizures in Japan?

“Dennō Senshi Porygon” was the Pokémon episode withdrawn after causing seizures in Japan.

The episode aired on December 16, 1997, during the first season of the Japanese anime. Near its climax, a scene used rapid red-and-blue flashing effects during an explosion. Hundreds of viewers reported symptoms such as seizures, dizziness, headaches, nausea, or temporary vision problems after watching the broadcast.

Japanese broadcasters and Pokémon’s production team responded by removing the episode from circulation. The anime then went on hiatus while production and broadcast practices were reviewed. The episode has not received a normal rebroadcast and is not part of the regular international episode rotation.

Although the episode is commonly called the “Porygon episode,” Pikachu is the character associated with the flashing attack shown in the scene. Porygon’s name became linked to the incident because it appears in the episode’s title and story, not because the Pokémon itself created the visual effect.