Parapsoriasis does not necessarily require phototherapy, but requires a visit to the hospital where the doctor will formulate a treatment plan according to your specific situation. The onset of psoriasis is related to bacterial infections, drug allergies, etc. Depending on the type of the disease, the size, distribution and thickness of the scales of the skin lesions vary to a certain extent, which will affect the choice of treatment program. Phototherapy involves irradiating the lesions with specific wavelengths of ultraviolet light, which destroys the structure of the diseased skin and achieves a therapeutic effect. In general, psoriasis is better treated with phototherapy. However, there are other treatment options, such as oral medication, local application of topical drugs, etc., which can achieve certain therapeutic effects. The specific treatment options used are recommended under the guidance of a dermatologist specializing in dermatology.