Watch: Richard Madeley reveals what caused his 'funny turn' on I'm A Celebrity
The 65-year-old TV presenter was forced to quit the ITV reality show last week after he suffered a 'funny turn' and was sent to hospital for a health check, meaning he had broken the camp's COVID bubble and was not allowed back in.
Madeley told Good Morning Britain: "I think I got dehydrated, that's all it was.
"Dehydration if anyone's ever suffered from it is actually quite disturbing. We were having very, very long days and sleeping quite late. I don't think I'd got to bed 'til about 4.30 in the morning. And I knew I was feeling thirsty.
"I'm quite bad at remembering to drink water. And as I snuggled into my sleeping bag and it was freezing, I remember thinking, 'I haven't had a big drink for a while. I'll do it when I wake up.'
"And the next thing I knew I was sitting there babbling, talking nonsense.
"I woke up, I didn't know where I was, what was going on and I could hardly string a sentence together.
"I went to the hospital had all the tests you can imagine, and I've got 100 per cent clean bill of health - by then I'd had a cup of tea and a drink of water. And I was back on the rails.
"But ITV has a proper duty of care, and if you've got somebody sitting in that castle talking nonsense, they've got to check it out."
The rest of the celebrity contestants - including former Saturdays singer Frankie Bridge, ex-Strictly Come Dancing judge Dame Arlene Phillips, retired footballer David Ginola and EastEnders actor Adam Woodyatt - have now been evacuated from the castle after the production site suffered significant storm damage.
They are quarantining off site before filming can resume.
However, Madeley was not allowed to return to the camp as he had broken the show's coronavirus restrictions by going to hospital.
He said: "I just couldn't go back. I wanted to - we talked about it. There's just no way I could risk taking the bug back in with me. I was out in the hospital, I was meeting people - the nurses and porters.
"We're all sleeping in the same dormitories, if anyone has the bug it's gonna spread."
Could you not have gone into quarantine and gone back in?@richardm56 says the risk of taking Covid back into the @imacelebrity castle was too high and would have 'killed the show'. pic.twitter.com/bbFET6Wnvg
— Good Morning Britain (@GMB) November 29, 2021
The TV presenter revealed he spent his first morning after leaving the show eating Spam sandwiches.
He revealed: "Between 9am on sat morning and 11.30am I ate two large tins of Spam.
"I really like Spam - it puts me back in the post-war generation. But it's gone a strong taste and I was absolutely starving.
"I had about 10 Spam sandwiches."
Watch: Richard Madeley took part in the Kitchen Nightmares trial