11 prisoners in total were taken to hospital following the incident earlier this week.
One prisoner remains in ICU this morning following the overdoses at Portlaoise Prison.
It's understood he's in a serious condition but is responding to treatment.
11 inmates in total had to be taken to hospital after a suspected synthetic drug was taken on Tuesday.
An investigation is now underway into what exactly the drug was and how it got into the jail.
Former Garda Commissioner Michael O'Sullivan says it's impossible to stop drugs getting into prisons.
Laois 10k Run and Family Fun Day Returns This Sunday
Fianna Fail Councillor Elected Tullamore Cathaoirleach
Outgoing Chair Of Offaly County Council Elected Birr Cathaoirleach
Midlands Showing Fast Growth In Mortgages For First Time Buyers
Plans For Major Laois Redevelopment Delayed
Enterprise Minister Expresses Concern Over Ticket Website Liquidation
Builders Behind Midlands Solar Farm Scoop Up Award For Construction Excellence
Laois TD Highlights Four Year Wait For Neurological Assessments
40 New Jobs On The Way To Laois
Westmeath Psychotherapist Warns Of Gambling Addictions
Katie Taylor Fight In Croke Park Sold Out
Sunshine Is On The Way For The Midlands
SIPTU Call For 'Full Answers' On Midlands College Closure
Westmeath Community Project Launching Strategic Plan Today
New Road Safety Campaign For Midlands Summer Events
Former Laois-Offaly Garda Sergeant Joins Muintir Na Tíre
Laois Accused Told Gardaí He Hit Deer After Fatal Collision
Business Leaders Meeting In Laois
Midlands Landscaper Granted Bail In Drug Case
Laois Leisure Centre Calls Gardaí Over Group's "Disgraceful Behaviour"