The ophthalmic division of the trigeminal nerve is one of the most commonly involved sites of postherpetic neuralgia (PHN). In this study, a significant difference in the overall changes for the mean pain scores was noted among 3 treatment approaches (local injection, intramuscular and oral) of local neurotrophic drugs describing local methylcobalamin therapy to be the most effective for pain relief (in 91% patients) in SOHN.

A single‐center randomized controlled trial was performed to examine the effectiveness of local methylcobalamin injection for the management of subacute ophthalmic herpetic neuralgia (SOHN).

All in all, 105 patients with a pain score of 4 or greater were randomized to be given methylcobalamin combined with lidocaine using local injection (LM, 35 patients), intramuscular methylcobalamin and local lidocaine injection (IM, 35 patients), and oral methylcobalamin tablet and lidocaine local injection (OM, 35 patients) for 4 weeks. The treatment responses were assesed via multilevel mixed modeling.

A significant reduction in pain scores was observed in patients who received local methylcobalamin (6.7 at baseline versus 2.8 at endpoint) than with systemic administration (IM 6.8 versus 4.9 and oral 6.7 versus 5.1). Clinically significant pain reduction of pain (more than 30%) was observed in 91% of patients in the local methylcobalamin group, a significantly greater proportion as compared to the systemic groups (66% IM and 57% oral). The use of analgesic decreased notably in the local group (94% at baseline versus 6% at endpoint) except systemic groups (IM 97% versus 86%, oral 94% versus 80%). Local group had an improved health‐related quality of life as compared to systemic groups. Higher age was related with a poorer response to methylcobalamin in mixed modeling.

Local injection of methylcobalamin provides significant pain relief from SOHN and is better than systemic administration.