Herpes labialis is an infection caused by the herpes simplex virus, characterized by an eruption of small and usually painful blisters on the skin of the lips, mouth, gums, or the skin around the mouth. Although there is no successful treatment available, the local use of compounds with effective anti-inflammatory and cytoprotective effects may be of value in this respect. This project was designed to evaluate clinically the local use of silymarin, a group of flavonoids with powerful antioxidant, anti-inflammatory and cytoprotective activity, in the treatment of herpes simplex ulcer. Fifty three patients with herpes labialis ulcers (HLU) were enrolled in this randomized, single blinded, placebo controlled clinical study, and they were allocated into 4 groups, treated with 1%, 3% and 5% silymarin paste and placebo formula respectively. Patient's responses to treatment were followed by clinical evaluation of healing time, size of the ulcers and pain sensation, in addition to evaluating biochemical and immunological markers of the oxidative stress and inflammatory response. HLU patients showed dose dependent improvement in the healing time, pain score and size of ulcer as a result of treatment with various concentrations (1%, 3% and 5%) of silymarin paste, associated with improvement in the oxidative stress state and immunological parameters. In conclusion, silymarin can be used locally as paste formula for the treatment of HLU, an effect which may be attributed to its antioxidant, anti-inflammatory and cytoprotective properties.

Keywords: Herpes labialis, ulcers, silymarin