There are different dosage forms for the same drug, such as solutions, pastes, powders, lotions, ointments emulsions and tinctures for psoriasis. Different dosage forms have different effects and indications, so they should be chosen according to the symptoms and characteristics of the lesions in different stages of the skin disease. If the skin is in the acute stage of local redness, blistering and erosion, the solution is mostly used for wet dressing, which can play an anti-inflammatory role; for those with exudate, the solution is used for wet dressing first, followed by the oil. When the lesions are in the subacute stage, the redness and swelling are reduced, the exudate is reduced, and the paste, powder and lotion can be used as appropriate to play its anti-inflammatory, anti-itch and astringent role. In the chronic stage, when the lesions are thickened and mossy, more ointments and emulsions are used, which have strong penetrating power, long-lasting effect and lubricating effect. It should also be noted: even if the same drug, the same dosage form, but also due to different concentrations and different effects. For example, 3% salicylic acid has the effect of softening and dissolving keratin, while 20% or more salicylic acid is an erosive agent.