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To the Editor.—
Upon checking my neutral red (0.1% aqueous solution) with a Wood lamp, I noted that it did not fluoresce. My alcohol-based (95% ethanol) neutral red has good fluorescence on a cotton-tipped applicator.A pharmacist mixed up two solutions, one alcoholic and the other aqueous from the same source of neutral red. Again only the alcoholic-based solution fluoresced. I am not able to explain this phenomenon, but since fluorescence is necessary for photoinactivation, I think that the previously mentioned information should be considered if neutral red is used (JAMA 223:289, 1973).
Brust SW. Neutral Red Fluorescence. Arch Dermatol. 1975;111(5):657. doi:10.1001/archderm.1975.01630170115022