Actress Ku Hye-sun has dropped out from MBC TV's weekend drama "You Are Too Much" due to health issues, the network and her agency said Friday.

"Ku was recently rushed to a hospital emergency room during filming, after showing symptoms of nausea and breathing problems," YG Entertainment, Ku's agency, said. 

The actress was diagnosed with a severe case of anaphylaxis, a type of serious allergic reaction, and was recommended by her doctor to undergo long-term treatment.

Ku was cast as the cover singer Jung Hae-dang, one of the main leads in the series just six episodes in.

"After consultations with the show's production team and medical experts, we made the difficult decision to drop out considering the actress' health priorities," the agency said.

MBC TV also said she played a "central role in the show," but the team agreed on her departure given her need to focus on recovering. The vacant role will be filled in by actress Jang Hee-jin.

"We started filming hurriedly from today. Jang made the difficult decision despite a great deal of pressure," said a representative at Jang's agency Lucky Company. (Yonhap)