Patsy Kensit thought she had dementia after losing her memory during the menopause.
The 54-year-old ex-Emmerdale actress was in "full on menopause" aged just 45 after an emergency hysterectomy.
The mum-of-two opened up about the effects of the condition on the Postcards from Midlife podcast.
Recalling coming round after her operation, she said: "I woke up in intensive care and I didn't know what I was doing, why I was there. I was in full-on menopause.
"I have always prided myself on having a great memory because I've learnt scripts my whole life – it's like a muscle.
"I couldn't remember a conversation, just a brain fog... I thought I had dementia. I went to see a therapist and got the HRT patch. It was not great."
Patsy was given a hormone therapy implant - a day before she was due to make an appearance on This Morning.
During the 2013 interview, the actress appeared to slur her words and told rambling anecdotes.
Looking back at the awkward incident, Patsy admitted she "should never have been allowed to do any promotion" while suffering such drastic side effects.
In a column written for The Sunday Times Style magazine, the performer explained her bizarre appearance.
She wrote: "Something was wrong: I felt like I had been drugged. I was nauseous, dizzy and terrified, with chronic blurred vision. I had also developed a slight stutter.
Despite pointing out she was in the middle of "full blown menopause", Patsy was slammed online and "accused of being on drugs and drunk".
She admitted: "I was ripped apart, vilified and held up as yet another fallen star."
Now, the star, who shares son Lennon with Oasis frontman Liam Gallagher, is trying to break the stigma surrounding the condition.
"My commitment is to bridge the divide between pre and post-menopausal women, who historically have felt as if we have nothing in common," she pledged.
"As a younger woman, I had no idea what was coming, but now I’m proud to be sharing information to educate and inform women of all ages about how to manage this transition without fear or prejudice."