The exact cause of psoriasis is not yet known, and it is currently believed that psoriasis may be related to genetic, environmental, and immune factors as well as neuropsychiatric and dietary factors. Topical medications are usually available clinically, including glucocorticoid creams, calcium-regulated phosphatase inhibitors, keratin enabling agents, vitamin D3 derivatives, and retinoids. There are also systemic medications that can be chosen from immunosuppressive agents, retinoids, and biologics. Physical therapy is also included, with common ones such as photochemotherapy, UVB phototherapy, and 308 excimer laser.