“It felt very real to me. I’m really new to panic attacks, so I need to learn more about it,” she added.
The Birmingham-born presenter, who also co-hosts The Great British Bake Off, thanked NHS staff and her colleagues at This Morning, including O’Leary.
“It’s really warmed my heart actually. I didn’t necessarily want to be on the news or anything like that but this is a new world to me,” she said.
“I’m going to take stock, take some rest and I’ll see you soon.”
Friday’s edition of the ITV show began at 10:00 BST with Hammond and her regular co-host O’Leary at the helm, before she left at 11:30 during a segment about pets.
O’Leary, 53, addressed her absence when the show returned from a break, saying: “Welcome back to This Morning, Alison is feeling a little unwell, so she’s just had to duck out. Hopefully she’ll be back.”
He later updated viewers that she would, in fact, not be returning, “so I’ll be here for the rest of the show”.
Hammond rose to fame as contestant on Channel 4 reality show Big Brother before appearing on I’m A Celebrity and Strictly Come Dancing.
She became a co-host in This Morning in 2021, and was part of the team that won a National Television Award for best daytime programme the following year.
She joined Bake Off in 2023 and took over from the late Paul O’Grady on For the Love of Dogs in 2024.