Methylene Blue and Light Therapy for Herpes Simplex

To the Editor.—  Photodynamic inactivation of herpesvirus by methylene blue was demonstrated in our laboratory. About 70% of freshly isolated strains of herpesvirus was found to be highly photosensitive after application of methylene blue at concentration of 10⁵M. Strains resistant to methylene blue were also resistant to neutral red, but were sensitive to proflavine, and vice versa.Our initial clinical trial on patients with recurrent genital herpes indicated that about 70% of 36 individuals treated with methylene blue and light improved: symptoms subsided in 48 hours, and the duration of the illness shortened appreciably. However, the relapse rate was not substantially reduced.Treatment consisted of application of 0.1% methylene blue and, 20 minutes later, exposure to either fluorescent light at a close distance or to sunlight whenever possible. The latter gave a better result. Treatment was carried out at home by the patient. This made treatment possible at