"Living with rheumatoid arthritis," O'Neal, 56, began in the caption. "A fall scratch scar on my right 😠hip. And the back surgery scar from eight years ago. My last back surgery scar is on the front from February."
"And all those red marks are from heating pads ~I probably should turn those down a little bit," she added.
Despite what the photo shows, the Oscar winner expressed, "believe it or not this is me actually getting better."
"Cheers to everyone and rheumatoid arthritis can go f--k itself," she wrote, adding the hashtag "#rheumatoidarthritiswarrior."
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O'Neal, who was diagnosed with the disease when she was 50, previously spoke about her battle with RA earlier this week. On Sunday, the "Bad News Bears" actress shared a black-and-white photo of herself smiling next to her dog and told her followers she's "on the mend."
"Hi, I've been in some rheumatoid arthritis bull crap but finally I'm feeling a little bit better," O'Neal captioned the pic. "I hate texting because my hands suck Right now.. so If I don't text you back I promise it's nothing personal. On the mend🤸♀️⛹️♀️🧘♀️🏇"
Last month, the "Paper Moon" star gave her followers a glimpse into her treatment. Sharing a photo of her medication, O'Neal wrote, "Second dose of #actemra hoping to get RA back to the way it's been Not like how it is which is lame !! #2020nomoreRA #rheumatoidarthritiswarrior"
Rheumatoid arthritis, also known as RA, is a chronic autoimmune disorder in which the body's immune system mistakenly attacks its own tissues, according to Mayo Clinic. The painful disease not only can affect the joints but can also damage other body systems, including the skin, eyes, lungs, kidneys and heart, in addition to blood vessels and nerve tissues.
According to the CDC, symptoms of RA can include chronic joint pain, stiffness, loss of joint function, weakness, weight loss and fatigue.