Material and Methods: In a randomized, single-blind, clinical trial conducted on patients with chronic low back pain, the impact of epidural injection of methylprednisolone, bupivacaine, normal saline in chronic low back pain due to disc herniation in three groups was randomly studied. Method of epidural injection in all groups was similar. In the first group, 80 mg of methylprednisolone in 10 cc volume, in the second group, local anesthesia drug, 10 mL of bupivacaine 0.5 %, and in the third group, 10 mL of normal saline solution (equal injected volumes) were prepared. During the injection, the patient was monitored in terms of pain, hemodynamics, consciousness, arterial oxygen saturation.

Results: Three months after treatment, the severity of pain in methylprednisolone group was less, the rate of disability in normal saline group was significantly high (P < 0.001) and also disability reduction rate in methylprednisolone group was significantly high (P < 0.001). In our study, the average time to return to daily activities in normal saline patients was significantly more (P = 0.005).

Conclusion: Epidural methylprednisolone and bupivacaine injection were more effective than placebo (normal saline) injection in these patients.