Swedish midfielder Christopher Olsson has been placed on a ventilator in hospital after losing consciousness at home.
Midtjylland said the 28-year-old former Arsenal player “suffers from what appears to be a severe brain-related illness.”
The Danish club announced that he was transferred to Aarhus University Hospital on February 20.
Midtjylland said they felt “compelled” to issue an update due to “increasing rumors and speculation surrounding Christopher Olsson's recent absence.”
“Everyone at FC Midtjylland has been deeply affected by Christopher's sudden illness,” the club said in a statement on Tuesday.
“Christopher Olson is suffering from what appears to be an acute brain-related illness, which is neither caused by self-harm of any kind nor by external factors.
“A team of senior Danish medical experts is currently working under pressure to make the diagnosis and initiate the correct treatment.”
Olsson came through Arsenal's youth academy and made one appearance for the Gunners before joining Midtjylland permanently midway through the 2014-15 Premier League season.
“I wish you a speedy recovery, Christopher. We wish you a full and speedy recovery,” Arsenal said on X, formerly known as Twitter.
Olsson, who has made 47 appearances for Sweden, had spells at Swedish club AIK, Krasnodar in Russia and Anderlecht in Belgium between two spells with Midtjylland.
“Keep fighting Kofi!” The Swedish Football Association said on X, formerly known as Twitter. “The entire Swedish football family is thinking of you and hopes that you recover soon. Our thoughts also go out to Christopher's loved ones at this difficult time.”
Olsson has missed Midtjylland's last two matches in the Danish league and made his last appearance for the club against Fredrikstad in the Atlantic Cup on 9 February.
“Since his acceptance, Christopher has been surrounded by his immediate family and members of the Midtjylland team, as well as industry professionals,” the club added.
“FC Midtjylland urges the public to show respect and understanding so that Christopher, his family and his doctors are allowed peace of mind to ensure Christopher improves and recovers as successfully as possible.”
