Methotrexate for treatment of lichen planus: old drug, new indication.

Treatment of generalized lichen planus is often disappointing and is associated with relapses. Though reports have suggested a beneficial role of various immunosuppressive and immunomodulatory agents, most of these reports are retrospective series or anecdotes. Oral methotrexate has been found to be useful in recent studies. In this study, we prospectively evaluated the role of low-dose oral methotrexate (15 mg/week in adults or 0.25 mg/kg/week for children) in generalized lichen planus. Mean improvement in 24 evaluated patients (two of them were of paediatric age group) at the end of 14 weeks of treatment was 79%. By the end of 24 weeks treatment, 14 of 24 (58%) patients had complete remission of their disease. Side effects were observed in 12 of 24 (50%) patients. Most of these adverse effects were mild; only one requiring treatment discontinuation due to significantly deranged liver function test. During post-treatment follow-up of 3 months, none had relapse of lichen planus. Overall, low- dose methotrexate is effective and reasonably safe option in treatment of eruptive lichen planus, provided haematological and biochemical parameters are regularly monitored.