Gehana, who was admitted to hospital on Thursday, is "extremely critical" as per hospital sources and has been put on ventilator and other life-saving equipment.
She is currently undergoing treatment in Raksha Hospital in Mumbai's Malad area.
As per the latest information received from hospital sources, the 31-year-old suffered a cardiac arrest resulting from a severe stroke and very low blood pressure.
Doctors suspect that this might have happened due to an adverse reaction between prescription drugs and certain energy drinks consumed by her.
As per sources, the actress fell unconscious on Thursday afternoon while shooting at Madh island for a web series. She was immediately rushed to the hospital.
Pranav Kabra, doctor and head of Raksha Hospital, has informed that Gehana was brought in with no pulse and extremely low blood pressure. He further revealed that it took two hours to revive her pulse and she had to be given electric shock treatment.
"She is not responding to treatment and has difficulty breathing on her own. We have put her on ventilator to ensure she has proper oxygen supply to her brain. You can describe her condition as extremely critical for now," said Kabra on Friday.
"From the preliminary information we have got so far, Gehana Vasisth was shooting for nearly 48 hours without consuming proper nourishment. She has been admitted to the Intensive Care section and we are doing a series of tests on her. She is suffering from diabetes and her sugar is on the higher side, while her BP is very low. We were told she consumed some energy drinks and was also taking medication for diabetes and some other ailment. We are not sure if there was any reaction between what she consumed. We have to wait for the results of all the tests," added the doctor.
On the work front, Gehana Vasisth was recently seen in ALT Balaji's "Gandii Baat". She has also featured in shows on the Ullu app.
( With inputs from IANS )