He was shifted to the NIMS on late Wednesday night, the fifth day of his hunger strike, from his fast camp and forcibly given fluids with police help.
Police removed Jagan from his indefinite hunger fast venue after doctors voiced concern over his deteriorating health. A team of policemen swooped down on Jagan's house in the posh Jubilee Hills area, lifted him and put him in an ambulance.
The Kadapa MP began his indefinite fast on October 5 in support of united Andhra Pradesh and doctors had advised that he should call it off since his blood sugar levels and other parameters were worrisome.
The YSRCP President had undertaken an indefinite fast while in jail last month on the same issue and was forced to break it then, too, after he was hospitalised.
The 40-year-old politician, who is facing corruption charges, was released on bail late last month.