Background and Objective: Medical cannabis is becoming an acceptable treatment modality in medicine, especially for pain relief. Concurrently, cannabis use is becoming more prevalent worldwide, a public demand-driven trend despite the lack of established scientific basis. This observational open-label study sought to investigate the effectiveness of cannabis therapy for alleviating low back pain symptoms.

Methods: Two types of cannabis treatment modalities were sequentially administered to chronic low back pain patients. After an initial 1-month washout period (WO1), the first modality was cannabidiol (CBD)-rich sublingual extract treatment administered for 10 months. Following another washout period, the second modality, Δ9-tetrahydrocannabinol (THC)-rich smoked inflorescence (whole dried cannabis flowers) was administered for 12 months.

Results: Enrolled in the study were 24 patients whose advanced imaging studies (i.e. computerized tomography or magnetic resonance imaging of the lumbar spine) revealed disc herniation or spinal stenosis. Three patients dropped out of extract therapy treatment but resumed study participation to receive THC-rich smoking therapy. After a minimum of 2 years, cannabis therapy had reduced lower back pain symptoms, as assessed by Oswestry Disability Index, the SF-12 patient-reported outcome questionnaire, and the visual analogue scale. Pain reduction was not significant during the extract treatment part of the study; however, pain reduction was significant during the inhaled therapy part of the study.

Conclusions: Our findings indicate that inhaled THC-rich therapy is more effective than CBD-rich sublingual extract therapy for treating low back pain and that cannabis therapy is safe and effective for chronic low back pain.