乾癬是慢性發炎的皮膚疾病，生物製劑為近代廣泛使用的治療。Ixekizumab為一種單株抗體，是針對與乾癬致病機轉的IL-17開發的藥物，已經核准並且用於臨床。在2024年一篇長期安全性報告中，有提及此藥物可能會誘發發炎性腸道疾病，雖然發生率極低，潰瘍性結腸炎為千分之三，克隆氏症為千分之二，但是依然值得注意。發炎性腸道疾病在亞洲族群發生率是低於歐美族群，並且此藥物在臨床實驗時，納入的亞洲族群日本人並無任何人罹病。但是我們以Ixekizumab治療一名28歲無任何過去病史及家族史的乾癬病人後，卻產生克隆氏症，其發生速度快，依仿單使用在第二劑施打完二天，就發生血便腹痛症狀，經大腸鏡檢查並切片證實，病人也在馬上停藥治療後，一周後緩解，七個月皆無復發，此一罕見使用Ixekizumab後快速發生克隆氏症病例報告，顯示臨床醫師早期發現，早期治療期，可獲得良好預後。

Psoriasis is a chronic inflammatory dermatosis. Ixekizumab is a monoclonal antibody that targets interleukin 17A (IL-17A) and indicated for plaque psoriasis. In 2024, a study analyzed the long-term safety of ixekizumab in patients with psoria-sis(6892 cases) and identified 31 cases of inflammatory bowel disease (IBD; 0.5%, incidence rate 0.2 per 100 PY), of which 18 were cases of ulcerative colitis (0.3%, incidence rate 0.1 per 100 PY) and 13 of Crohn’s disease (CD; 0.2%, incidence rate 0.7 per 100 PY). However, subgroup analysis of Japanese patients in a phase III study on ixekizumab uncovered no cases of IBD. The literature suggest that CD fol-lowing ixekizumab therapy is uncommon, especially in Asian patients. Herein, we report the case of a Taiwanese patient who developed rapid-onset de novo CD fol-lowing ixekizumab therapy for chronic plaque psoriasis. Ixekizumab therapy was administered as per the instruction sheet, and his symptoms appeared 2 days follow-ing the 2nd dose of ixekizumab. Due to the rarity, we report this case to highlight the importance of adverse event. Early detection and diagnosis result in a good outcome. Physicians should be alert to its possibility. Careful history taking of gastrointestinal symptoms is recommended before and after anti-IL-17 therapy.