Symptoms include abnormally painful periods, ones Dunham experienced from the time she first began menstruating, she wrote.

From the first time I got my period, it didnt feel right, she said.

Dunham ended the piece by clarifying that endometriosis is not life-threatening and wrote about how it changed her life.

Lena Dunham

Credit: Jason Merritt/Getty Images

But I am strongbecauseof what Ive dealt with … And I am no longer scared of my body.

In fact, I listen to it when it speaks.

Read the full essayhereand see her Facebook post below.Girls fifth seasonpremieres Feb. 21 at 10 p.m.