"As many of you know, I have endometriosis, a chronic condition that affects approximately 1 in 100 women's reproductive health," Dunham said in her post. "I am currently going through a rough patch with the illness and my body (along with my amazing doctors) let me know, in no uncertain terms, that it's time to rest."
Endometriosis is a disorder in which tissue that would typically line the inside of a woman's uterus, known as endometrium, grows outside the uterus itself, often plaguing the ovaries, bowel or pelvic lining. The condition can cause intense pain and bleeding, as well as cysts and scar tissue, sometimes causing significant fertility issues.
Dunham's struggle with the condition comes as no surprise to fans, as the actress shared the story of her diagnosis and ongoing battle with endometriosis in a November 2015 post on Lenny, the email newsletter she created with "Girls" co-showrunner Jenni Konner.
"The feeling of stopping a crew of 100 people from doing their jobs is far more stressful than missing Intro to Greek Drama class at a liberal-arts college, but I felt the same sense of hot shame," Dunham wrote in her post. "The kind of shame you feel as someone with an anxiety disorder that plays tricks on them. The kind of shame you feel as a woman showing weakness."
Dunham goes on to reveal the extent of her endometriosis, diagnosed at "stage two," and she spoke of the simple relief of knowing that the pain she'd found so incapacitating was not all in her head.
"It's a sad and beautiful moment when you realize just how much you have let yourself endure."
With HBO announcing in January that Season 6 will be the final bow for Dunham's comedy about four friends living and growing in New York City, it's unclear how much time she will be able to afford to let herself heal, something that even she recognizes is a luxury.
"So many women with this disease literally don't have the option of time off," Dunham observed in her Instagram post, "and I won't take it for granted."
"Girls" Season 5 premieres on Feb. 21 on HBO. Season 6 is scheduled to air in 2017.
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