The dysregulated inflammatory process not only plays an important role in the development of chronic plaque psoriasis but also is a major pathogenetic mechanism behind the generalized pustular psoriasis (GPP) and other rare pustular forms of the disease. The key players in this process are the cytokines interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF), IL-12/23, IL-17A and especially IL-36. Their excessive activity or production in some GPP patients is due to mutations in genes that encode molecules involved in inhibiting the action of IL-36 (IL-36Ra) or in intracellular inflammatory signaling (CARD14, AP1S3). Knowledge about the pathological role of inflammatory cytokines in the development of pustular forms of psoriasis has also found application in their biological therapy with monoclonal antibodies that neutralize the action of IL-12/23, IL-17A, TNF or IL-1β. Other promising agents are monoclonal antibodies against the interleukin 36 receptor, which have already successfully gone through the first phases of clinical trials and are currently being tested for their long-term efficacy, safety and tolerability.