Background and Objectives Lidocaine infusion therapy (LIT) is an effective treatment for relieving neuropathic pain (NeP). However, it remains unclear whether pain relief can be sustained through repeated lidocaine infusions. This study aimed to determine whether repeated intravenous administration of low-dose lidocaine could provide prolonged pain relief in patients with specific NeP conditions.

Methods This is a prospective, randomized, double-blind, placebo-controlled, parallel study. We compared the efficacy and safety of lidocaine infusions (3 mg/kg) in the LIT group and normal saline infusions in the control group once a week for 4 consecutive weeks in patients with postherpetic neuralgia or complex regional pain syndrome type II. The primary outcome was the difference in the percentage change in the 11-point numerical rating scale (NRS) pain score from baseline to after the final infusion. Secondary outcomes included pain scores during 4 weeks of follow-up and any complications.

Results Forty-two patients completed this study protocol. The percentage reduction in NRS pain scores after the final infusion was significantly greater in the LIT group compared with the control group (P = 0.011). However, this pain reduction was not detectable at the 4-week follow-up. The difference in the percentage change in NRS pain scores was especially prominent in the LIT group after the third and fourth infusions. None of the study participants experienced serious complications from the treatment.

Conclusions Lidocaine infusion therapy (3 mg/kg of lidocaine administered over 1 hour) provided effective short-term pain relief, which was substantially prominent after repeated infusions were administered to patients with refractory NeP.

Clinical Trial Registration This study was registered at ClinicalTrials.gov, identifier NCT02597257.