"It was never ever a stroke," her publicist Elliot Mintz tells PEOPLE.
"She was suffering extreme flu like symptoms. Her doctor thought it would be a good idea to go to a local hospital to be checked out. She went to hospital. She is being checked out. The information that she has been given is that in all likelihood she will be out tomorrow."
Ono, 83, is currently being treated at Mount Sinai Roosevelt hospital – the same place her late husband and legendary musician John Lennon died in 1980 after he was shot.
There had been false reports that the legendary artist and activist had suffered a stroke.
Ono's son, Sean Ono Lennon, later took to Twitter, clarifying that any reports that his mother had suffered a stroke were false.
Hey guys it was only rumors from press: was NOT a stroke, just dehydration/tired. She is FINE. Thank you everyone for your concern @yokoono— Sean Ono Lennon (@seanonolennon) February 27, 2016
"Hey guys it was only rumors from press: was NOT a stroke, just dehydration/tired. She is FINE," he tweeted late Friday. "Thank you everyone for your concern @yokoono."
Ono hasn't had any recently reported medical problems and last week made an appearance in London at at the NME Awards 2016 with Austin, Texas, where she was presented with the NME Inspiration Award.
She said at the event: "I'm excited to get this award. I didn't expect it at all. It's great to be busy together."