Endometriosis is a condition that primarily affects the lining of the uterus. When this lining spreads, it can grow on and around nearby organs, and eventually damage them. Endometriosis can cause a great deal of pain and discomfort, and is often mistaken for menstrual pain. The condition can only be treated by hormonal therapy or surgery. The doctor may also prescribe the use of anti-inflammatory medications. For some patients, marijuana may be a better option for pain relief than these medications.