Pinkett Smith, 50, captioned a video about dealing with the autoimmune disorder, "Me and this alopecia are going to be friends."
In the video, the Matrix Resurrections star pointed out bare patches on her scalp and said she was embracing them.
"Now at this point, I can only laugh. Y'all know I've been struggling with alopecia and just all of a sudden one day, look at this line right here. Look at that," she says in the video, as she points to a line on her head.
"It just showed up like that and this is going to be a little bit more difficult for me to hide. So I thought I'd just share it so y'all are not asking any questions."
She then said that she was going to "put some rhinestones in there" and make herself a crown.
In the caption, she explained that she shared the alopecia update so that "nobody thinks she got brain surgery", suggesting that fans could mistake the hairless patch on her scalp for a scar.
Pinkett Smith, who is married to actor Will Smith, 53, has spoken about her hair loss in the past.
In 2018, she said in a conversation on her Facebook Watch show Red Table Talk she was using steroid injections.
"I’m getting my little steroid injections, and they seem to be helping, but not curing, but they seem to be helping, but I’m open to other ideas,” she said.
“I just want to say a thank you to everyone for all the outreach, from all the doctors and all the holistic practitioners, who have been reaching out to me for this head of mine, I appreciate it so much,” she said. “And I’m taking into a lot of consideration all the recommendations that are coming my way.”