The TV presenter has suffered from alopecia since 2005, the same year that she split from her husband Dan Hipgrave from Toploader.
Porter was sectioned under the Metal Health Act last year, over fears she had become suicidal.
In the past year she has been writing a book on her experiences, but she has now said that she is going to attend rehab once again.
The 41-year-old will live in the Cape Town facility for three months, to be treated for depression and alcohol addiction.
Whilst there, she will not allowed to contact others, and will not have access to a phone. She will however be allowed to use Skype to make short calls to her 9-year-old daughter.
"I'm terrified. I'm scared to death. But I also think this is the happiest I've ever been. I think this is the best thing I could do to get me out of the state I'm in," she told The Sun.
Talking about her struggles, she explained: "I've always had an addictive nature. It isn't just drinking. I'm addicted to everything, even to cleaning.
"Recently, I've put on a brave face in the media but the truth is that I'm really upset and I need help. So I'm off to try to sort my head out. Not my hair, but my head.
"I try to cope with everything through humour. But not a day goes by without someone in the street laughing at me or pointing at me.
"The other day, a little kid in the bus pointed and yelled, 'You've got no hair!' So I went, 'I left it on the bus. It's on the C11 and I can't find it'."
On her career, she added: "When my hair fell out, I thought there was no coming back to TV for me. As much as everyone said they would stick by me, no-one did.
"I don't get the programmes I used to and that depresses me."
Gail Porter also dismissed reports that she had tried to kill herself in the past, saying: "It was reported that I made a suicide attempt. But that isn't true. I wouldn't, in a million years, try to kill myself.
"I took an accidental overdose of painkillers, then called the doctors myself.
"I was very depressed, I was trying to sleep but I didn't want to kill myself. That's why I called the doctor and told him that I'd taken too many painkillers, and ended up in hospital."