Systemic therapy for psoriasis has changed markedly with the advent of biologics. Various studies have provided real-world evidence of their efficacy, adverse reactions, and continuation rates.The development of oral anti-psoriatic drugs has been relatively slow, and conventional oral drugs have long been used. Etretinate was first approved for use in psoriasis in Japan in 1985, followed by cyclosporine in 1992. Methotrexate has been the most frequently used systemic treatment globally since the 1970s 1 ; however, it was approved for psoriasis in Japan only in 2019. Although effective, cyclosporine is not recommended for long-term continuous use because of its renal toxicity. 2,3 The unavailability of methotrexate has sometimes forced Japanese dermatologists to administer cyclosporine