Platelet-Rich Plasma for Postherpetic Neuralgia: Proposed Mechanisms, Clinical Evidence, and Future Research Directions.

This is a narrative review. A structured literature search was performed across major medical databases to identify relevant pre-clinical and clinical studies investigating PRP for PHN. In total, 10 clinical studies of varied designs were included in this review. Postherpetic neuralgia (PHN) is a refractory neuropathic pain condition characterized by persistent pain lasting more than three months after the resolution of acute herpes zoster. Current pharmacological and interventional treatments primarily focus on symptom modulation, leaving an unmet need for therapies that target the underlying neural damage. As a regenerative therapy with proposed dual mechanisms of anti-inflammatory immunomodulation and potential neural repair, platelet-rich plasma (PRP) delivers high concentrations of growth factors that have been proposed to promote axonal regeneration and Schwann cell activation, while shifting macrophage polarization from the pro-inflammatory M1 to the anti-inflammatory M2 phenotype, thereby potentially alleviating peripheral and central sensitization. Preliminary clinical observations suggest that PRP monotherapy or PRP combined with pulsed radiofrequency (PRF) may reduce pain intensity, improve sleep quality, and decrease subsequent reliance on gabapentinoids. Combined regimens have been suggested to yield potential synergistic benefits by integrating immediate neuromodulation with hypothesized long-term neural-restorative effects. Current small-scale findings suggest PRP is generally well-tolerated and minimally-invasive for PHN. However, substantial heterogeneity in PRP-preparation protocols and injection methodologies, small sample sizes, geographic concentration of cohorts, active-comparator designs and short follow-up durations across studies limit precise efficacy evaluation. PRP remains investigational for PHN given the absence of direct human evidence for neural repair. Future research should prioritize large‑scale, multicenter randomized controlled trials with extended follow‑up and standardized assessment frameworks to clarify its impact on the natural history of PHN and optimize therapeutic application.