Kelly Osbourne was filming her television show Fashion Police in front of a full studio audience when she turned to Melissa Rivers - daughter of comedian Joan - and said "I don't feel good", according to celebrity website TMZ.
The daughter of Sharon and Ozzy then reportedly fell out of her chair before the seizure begun.
An audience member, believed to be an emergency responder, ran up to help Ms Osbourne.
More top news
Around 40% of workers admitted to working despite being too sick for the office, a survey has revealed.
High street stores con customers by offering "discounts" which offer little to no savings - and may end up costing more, Which? has claimed.
Britain has claimed victory over Germany in a special football match marking 100 years since the near-legendary WWI Christmas truce match.