Psoriasis is treated with an infrared absorbing compound, preferably but not exclusively by occluding psoriatic lesions with a plastic film containing at least one compound which strongly absorbs infrared radiation in the range of from about 700 to about 1400 nanometers. The invention also includes a dressing for treating psoriasis incorporating one or more infrared blocking compounds. The infrared absorbing materials are preferably but not necessarily dispersed uniformly through a flexible carrier transparent to visible light, such as polyvinyl chloride (PVC) film or poly (methyl methacrylate) (PMMA) film, by known techniques of solution casting or dying. The materials can be used as the sole therapeutic agent, or as an adjunct to local and/or systemic treatments for psoriasis.