Tigers coach Damien Hardwick revealed that Cousins would not be selected when he spoke ahead of Richmond training on Thursday morning.
"No, he won't play," Hardwick said at Victoria Park.
"He's had a far from ideal preparation; he's been in intensive care on Monday and Tuesday."
Cousins spent time in Epworth Hospital after experiencing a reaction to sleeping tablets he took on Sunday night. He later said the incident was due to an incorrect dosage and stated his intention to swear off the tablets.
Hardwick said the hospitalisation, combined with the short break, meant his veteran onballer was never in the mix to face Freo.
"At Ben's age with a six-day break ... it's not the ideal preparation so he won't play this week.
"He'll suit up against the Kangas in a week's time."
Cousins has been in solid form over the past month, a run that has coincided with Richmond winning three out of four games.
A win against fourth-placed Fremantle would take the Tigers to five wins and within striking distance of what would be one of the most unlikely finals campaigns in AFL history.
Cousins did train with his teammates on Thursday and appeared to be moving normally.
Hardwick says the 2005 Brownlow Medallist was disappointed when he was told he would miss this week.
"He is a competitive animal, there’s no doubt about that. He was eager to play," he said.
"He was very disappointed when I told him he wasn’t going to play but for the good of the Richmond Football Club and the good of Ben’s health, physically-wise, it wasn’t a hard decision to make."
The Tigers coach admitted he struggled to comprehend the series of events that played out on Monday that led to Cousins being hospitalised.
"No I couldn’t [believe it]; that was the scary thing about it.
"To know that one of your players has gone into intensive care you just want to drop everything and find out what the hell is going on and go and see him. We couldn’t at that stage. It was a massively concerning time for the footy club."
Hardwick said the Tigers discouraged their younger players from using medication to pump themselves up and then calm them down after games, but accepted that some of the more experienced players were set in their routines.
"It's a personal decision because it is legal within AFL circles," he said.
"We just give them all the facts and say this is the research we’ve got and they’ll make a decision."
