To understand how ORILISSA works in your body, let’s start at the beginning
What is endometriosis?Endometriosis occurs when tissue similar to the endometrium—the tissue that lines the inside of the uterus—grows outside of the uterus where it doesn’t belong. These out-of-place growths are called lesions (doctors may also call them implants).
How do lesions grow and why do they cause pain?During your menstrual cycle, when estrogen levels rise, these lesions can grow. And later, during your period, the lesions can break down and shed. This can cause pain throughout the month.
One way to manage common symptoms of endometriosis is to reduce the amount of estrogen your body produces. Learn more about endometriosis.
How does ORILISSA work?ORILISSA is a gonadotropin-releasing hormone (GnRH) receptor blocker. It works in the pituitary gland (located at the base of your brain). By blocking GnRH receptors, ORILISSA decreases signals to your ovaries to produce estrogen. This leads to reduced estrogen levels. Your level of estrogen reduction will depend on the dose of ORILISSA you take.
How do lesions grow and why do they cause pain?
During your menstrual cycle, when estrogen levels rise, these lesions can grow. And later, during your period, the lesions can break down and shed. This can cause pain throughout the month. 
