Radiation-induced cutaneous ulcers are a challenging medical problem for patients receiving radiation therapy. The inhibition of cell senescence has been suggested as a prospective strategy to prevent radiation ulcers. However, there is no effective treatment for senescent cells in radiation ulcers. In this study, we investigated whether zileuton alleviated radiation-induced cutaneous ulcer by focusing on cell senescence. We demonstrate increased cell senescence and senescence-associated secretory phenotype (SASP) in irradiated dermal fibroblasts and skin tissue. The SASP secreted from senescent cells induces senescence in adjacent cells. In addition, 5-lipoxygenase (5-LO) expression increased in irradiated dermal fibroblasts and skin tissue, and SASP and cell senescence were regulated by 5-LO through p38 phosphorylation. Finally, the inhibition of 5-LO following treatment with zileuton inhibited SASP and mitigated radiation ulcers in animal models. Our results demonstrate that inhibition of SASP from senescent cells by zileuton can effectively mitigate radiation-induced cutaneous ulcers, indicating that inhibition of 5-LO might be a viable strategy for patients with this condition.