It is estimated that as many as one in nine females have endometriosis — an inflammatory condition where tissue similar to the internal lining of the uterus grows outside that organ.
The condition commonly causes chronic, severe pelvic pain, heavy or irregular bleeding, infertility, bladder and bowel issues and extreme fatigue.
A recent study by the University of Otago (Wellington) has found taking cannabidiol (CBD) oil — alone or in combination with dried cannabis flower — for three months could reduce pain, improve sleep and lower anxiety.
Surgery and critical care researcher Dr Claire Henry, who led the study, said it involved 28 people with endometriosis and/or related pelvic pain, and was the first prospective cohort study of medicinal cannabis for endometriosis-related pain in New Zealand.
The participants recorded weekly pain scores on a 0 to 10 scale
and completed endometriosis health questionnaires before and at the end of the 12-week trial.
During the study they were prescribed CBD alone or in combination with dried cannabis flower.
At the end of the study, 17 women were interviewed about their experiences.
Dr Henry said pelvic pain among the group dropped from a level of 5.4 to 3.7, and the level of the worst pain dropped from 7.6 to 5.3.
"There was a clinically meaningful improvement in their health-related quality of life scores.
"While CBD did not work for everyone, for some the impacts were life-changing."
She said one of the participants talked of preparing to re-enter the workforce after three years out, while another was starting to try to have a baby.
Dr Henry said present treatments included pain management, hormonal medications and laparoscopic surgery.
"However, medical management of endometriosis is often associated with side effects, and patient satisfaction with these treatments can be limited."
Those in the trial were using personalised combinations of analgesic, contraceptive and holistic medication, as well as lifestyle modifications in an attempt to self-manage their pain.
Several of the participants reported opioid-based analgesics provided limited or inconsistent relief and were often accompanied by undesirable side effects, including nausea, dizziness and fatigue.
There were few side effects reported from CBD, with participants perceiving it as a gentler alternative that could still offer effective relief.
However, Dr Henry said large-scale studies and clinical trials were needed.
"Endometriosis pain management is often complex and individualised, and while CDB had benefits in terms of pain relief and improved sleep for many of our participants, we still need to understand how it works and what the long-term effects from its use might be."
