After receiving complaints from an epilepsy charity, Twitter pulled a brightly colored, flashing Vine advertisement from its website Friday.

@TwitterUK had uploaded two short videos featuring a rapid succession of flashing colors for its new #DiscoverMusic campaign, which is designed to promote new artists. Epilepsy Action, a charity focused on providing information about the condition, tweeted about the ads, calling them “massively dangerous.”

The ad was up for 18 hours before it was removed. Rachel Bremer, Twitter’s international communications director, tweeted back at Epilepsy Action thanking them for their feedback and saying that the ads had been removed. Epilepsy Action said it was “pleased” that Twitter removed the ads.

"Twitter's ads were dangerous to people living with photo-sensitive epilepsy," Epilepsy Action's Deputy Chief Executive Simon Wigglesworth told BBC.

Epilepsy is a chronic disorder, the hallmark symptom of which is recurrent, unprovoked seizures. There are over 65 million people diagnosed with epilepsy worldwide, making it the fourth most common neurological disorder. With Twitter’s massive online presence, the ads — whose bright lights and bold patterns could potentially produce seizures in those with light-sensitive epilepsy — would have reached many people. In the UK alone, about 3,500 people suffer from photosensitive epilepsy, according to Epilepsy Action.

"Eighty-seven people are diagnosed with epilepsy every day and that first seizure can often come out of nowhere," Wigglesworth said." For a huge corporation like Twitter to take that risk was irresponsible."

The Advertising Standards Authority told BBC that "marketing communications," even those uploaded on a company's own website, should not include "visual effects or techniques that are likely to adversely affect members of the public with photosensitive epilepsy."

In 1997, an episode of the popular cartoon Pokémon was blamed for triggering seizures. The incident helped pinpoint a specific type of epilepsy; one where color changes trigger a seizure rather than only light changes. This led Japanese researchers to propose a subcategory of photosensitive epilepsy called chromatic sensitive epilepsy.

Any type of photosensitive epileptic could have been affected by the Twitter ad since it included both light and color changes. But hopefully Twitter removed the ad before it happened.