Methylcobalamin (MeCbl) is the activated form of vitamin B12, has been used to treat some nutritional diseases and other diseases in clinic, such as Alzheimer’s disease and rheumatoid arthritis. B12 group of vitamins had been used to treat pain. Lidocaine is a local anesthetic (numbing medication). This research draws attention towards MeCbl combined with lidocaine which proved to have potential analgesic effect in patients with herpetic neuralgia. 

To determine the efficacy of methylcobalamin combined with lidocaine for acute herpetic neuralgia.

Design- Randomized controlled trial with longitudinal analysis. Subjects. The authors recruited 204 patients (>50 years) with T5-10 dermatomal acute herpetic neuralgia with rash onset within 7 days. Patients were divided into two groups based on the time of onset: immediate-early (IE, 1–3 days) and early stage (ES, 4–7 days) groups and then subdivided randomly into control (IE-Ctl, ES-Ctl) and treatment (IE-Tr, ES-Tr) groups.

Control groups received intramuscular methylcobalamin in addition to local lidocaine injection, while treatment groups received local methylcobalamin combined with lidocaine injection for 14 days. Treatment efficacy was assessed based on rash healing time, alteration in pain intensity, and interference with quality of life. Multilevel mixed modeling and survival analysis were employed to examine treatment responses.

There was no significant difference in the rash healing time between IE and ES. The mean pain scores in IE-Tr (2.4 ± 0.7) and ES-Tr (1.3 ± 0.7) decreased significantly compared with those in the control groups. The median satisfactory response time was 6 days in ES-Tr and 11 days in IE-Tr. The benefit ratio for ES-Tr versus IE-Tr was 14.94. The subjects in IE-Tr and ES-Tr had higher quality of life scores (81.2 ± 6.9 vs 88.3 ± 8.6, respectively) than those in the control groups. The incidence of post herpetic neuralgia was 1.1% at 3 months.

Local methylcobalamin combined with lidocaine, optimally administered within 4–7 days of onset, may be an effective therapeutic option for acute herpetic neuralgia.