The Football Association will take no action against Sheffield United captain Chris Morgan following a clash which left Barnsley striker Iain Hume with a fractured skull.
Hume was last night readmitted to hospital just over two weeks after the incident during the local derby at Oakwell on 8 November.
He is understood to have spent the night at Salford Royal as a precaution after complaining of feeling unwell at home in Oldham but is expected to return home tomorrow.
Morgan was booked for the challenge during the match and there were suggestions he could be facing a lengthy ban.
But an FA spokesman said: "When judging whether to take disciplinary action in this case, the FA has had to consider the challenge itself and not the outcome of it.
"The FA has been given express direction from Fifa that we cannot upgrade yellow cards to red.
"On this basis we can only bring additional charges in the most exceptional cases and only if it can be proved beyond doubt the actions of a player were a deliberate attempt to injure an opponent.
"Having reviewed all available evidence in this case, including submissions made by Barnsley, there is no basis on which an additional charge could be brought."
Hume, 25, was released from hospital seven days ago and has since been recovering at home before being readmitted.
A statement from Barnsley read: "Iain Hume was readmitted to hospital yesterday complaining of feeling unwell.
"This is due to an infection and he has been prescribed a course of antibiotics.
"He will mostly likely spend tonight in hospital purely as a precaution and should be back home on Wednesday."
In a statement on their official website, Barnsley said they were "extremely disappointed and concerned" that the FA was taking no action.
"The decision by the FA to disconnect a violent act from its consequences runs contrary to the principles of civil and criminal law," the statement said.
"The FA's failure to act has let Iain Hume down badly and the only option now remaining is for recourse outside of the normal football processes."