Twitter has been criticized by an epilepsy charity for some flashing ads that were produced recently on the social media. The ads with series of flashing brightly colored screens promoting Twitter pages was flagged as potentially harmimg to Epilepsy sufferers. Around one in 3,500 people in the UK has photosensitive epilepsy, according to Epilepsy Action and Seizures can be triggered by flashing lights and bold patterns. Twitter removed the videos on Friday morning.