Korean media reported the 36-year-old star was found at about 5 am by a friend at her apartment in Songdo International City in Yeonsu District.
Oh In-Hye (Instagram)
According to the Incheon Yeonsu Police, the actress had a cardiac arrest.
The same friend reportedly called 112 emergency hotline to report on her condition.
Oh received cardiopulmonary resuscitation (CPR) before being taken to a hospital where her breathing and pulse normalized.
The police said they are still investigating the incident.
Her last post on her Instagram account was on Sept. 12 wherein she posted selfies and wished everyone a great weekend. She also uploaded a skin care tutorial on her YouTube account on Sept. 12.
Oh signed an exclusive contract with Redline Entertainment in 2017 but her contract with the company has reportedly expired since.
She made her acting debut in the movie “Sin of the Family” in 2011.
Her other movie credits include “Red Vacance Black Wedding,” “No Breathing” in 2013” and “The Plan” in 2014.
She made a special appearance in the drama “Yeonnam-dong 539” in 2018.