A further three inmates have been taken to hospital amid a spate of drug overdoses at HMP Shotts.
The men are believed to have become seriously ill after a batch of illegal narcotics were smuggled into the jail.
The Daily Record reports one man is still being treated and a further two have since been released.
Two weeks ago six prisoners from the same landing were rushed to University Hospital Wishaw after being found unresponsive a fortnight ago.
The Scottish Prison Service confirmed another three were taken to hospital last Monday.
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It is understood the nine men ingested a drug used to make "spice"
Now prison officials fear fatal consequences are 'inevitable' if what will happen if prisoners keep taking the dangerous substances.
A spokesperson for the Scottish Prison Service told the Daily Record: "One prisoner is still in hospital and it is inevitable someone will die if they keep taking this stuff.
"It is unbelievable that people have seen others take these drugs in the prison with these consequences and continue to take them themselves."
Justice Secretary Keith Brown yesterday told the Scottish Parliament that a prison rule change will be brought in that will see inmates' mail photocopied before being handed to them in a bid to prevent drugs getting inside.
The SPS faces an ongoing battle to prevent substances getting into prisons as there are so many different types, and chemical formulae constantly evolves, which helps avoid detection tests.
