The 84-year-old had been at Old Trafford for the match between the two rivals.
Sky Sports reported that Ferguson was conscious and had precautionary checks before being whisked away.
Ferguson, who managed United from 1986 until his retirement in 2013, won 13 Premier League titles and two Champions League trophies during a glittering 26-year spell at the club.
He hoisted a total of 38 trophies with United.
A United spokesperson said the club was unable to comment on Ferguson's status.
Ferguson is a regular at United's home games and has a row of seats in the Old Trafford directors' box.