But this viral Facebook post is bringing it into the open — in a good way.
On May 25, Aimee Rouski shared photos of her scars from her surgery and her ileostomy — to combat the idea that because her illness isn't immediately visible, it isn't serious.
She also wanted to send a message about body positivity.
"I've wanted to do this for a while because I always see body-posi posts for weight, but not many for disabilities/invisible illnesses," Rouski wrote on Facebook.
Her diagnosis has shaped her body and life. "My Crohn's has left me with a permanent ileostomy, no large intestine, colon, rectum, anus or inner thigh muscles as they were used for plastic surgery on my wounds. ... People who know will still love you and still find you beautiful."
"Your illness is nothing to be ashamed or embarrassed about."
Rouski's post has been shared more than 5,000 times on Facebook and has attracted hundreds of comments, many thanking her for inspiring and educating.