A liquid composition for use in the treatment of psoriasis or ichtyosis in the scalp, or for treatment of psoriasis or ichtyosis on other skin than the one on the scalp. The composition is used for wash of scalp or skin, and including at least: 13.5-24.0% Mild wash tensides, 1.0-4.7% Guar HydroxrypropyltrimoniumCloride, and 0.3-1.0% Piroctone Olamine. The composition is preferably washed away with liquid after use, but is preferably left to work for 2-5 minutes before it is washed away.