Clinical pharmacists participated in the drug therapy and monitoring of a patient with Crohn's disease complicated with erythema multiforme. The patient, who had a previous diagnosis of Crohn's disease for many years and had been treated with infliximab to date, was admitted to the hospital with a scattered rash on the peripheral skin, normal stools, and fecal calprotectin >1 800 μg·g^-1, by collecting the patient's medical history, reviewing domestic and foreign literature, the clinical pharmacist assisted the physician in ruling out drug factors, and making a definitive diagnosis of Crohn's disease complicated with extraintestinal manifestations.  Taking into account the patient's condition and guideline recommendations, the clinical pharmacist assisted doctors to adjust medication regimen, and determined that the next step in the patient's treatment program was ustekinumab combined with glucocorticoids therapy, and continuously monitoring the patient's condition. The patient's condition was effectively controlled immediately before discharge, with marked improvement in erythema multiforme, and the patient was followed up 3 months later with complete disappearance of erythema multiforme, normal bowel movements, and no specific discomfort. Since the extraintestinal manifestations of Crohn's disease are often similar to the adverse reactions caused by medications used in the treatment or other systemic diseases and disorders, it is necessary for the clinical pharmacist to assist the physician in screening. The case was studied and compiled with a view to providing references for the diagnosis and pharmacological treatment of such patients.

1.Magro F, Gionchetti P, Eliakim Ｒ, et al. Third European evidence-based consensus on diagnosis and management of ulcerative colitis. Part 1: definitions, diagnosis, extra-intestinal manifestations, pregnancy, cancer surveillance, surgery, and ileo-anal pouch disorders[J]. J Crohns Colitis, 2017, 11( 6) : 649-670. DOI: 10.1093/ecco-jcc/jjx008.

2.Gionchetti P, Dignass A, Danese S, et al. 3rd European evidence-based consensus on the diagnosis and management of Crohn's disease 2016: Part2: surgical management and special situations[J]. J Crohns Colitis, 2017, 11(2): 135-149. DOI: 10.1093/ecco-jcc/jjw169.

3.Georgesen C, Huang J, Avarbock A, et al. Orofacial granulomatosis and erythema multiforme in an adolescent with Crohn's disease[J]. Pediatr Dermatol, 2018, 35(5): e294-e297. DOI: 10.1111/pde.13548.

4.田霞, 韩峥, 黄晓东. 干扰炎症性肠病诊断的若干疾病[J]. 医学新知, 2022, 32(4): 281-288. [Tian X, Han  Z, Huang XD. Several diseases that interfere with the differential diagnosis of inflammatory bowel disease[J]. Yi Xue Xin Zhi, 2022, 32(4): 281-288.] DOI: 10.12173/j.issn. 1004-5511.202203049.

5.Hedin CRH, Vavricka SR, Stagg AJ, et al. The pathogenesis of extraintestinal manifestations: implications for IBD research, diagnosis, and therapy[J]. J Crohns Colitis, 2019, 13(5): 541-554. DOI: 10.1093/ecco-jcc/jjy191.

6.Harbord M, Annese V, Vavricka SR, et al. The first European evidencebased consensus on extra-intestinal manifestations in inflammatory bowel disease[J]. J Crohns Colitis, 2016, 10(3): 239-254. DOI: 10.1093/ecco-jcc/jjv213.

7.Rogler G, Singh A, Kavanaugh A, et al. Extraintestinal manifestations of inflammatory bowel disease: current concepts, treatment, and implications for disease management[J]. Gastroenterology, 2021, 161(4): 1118-1132. DOI: 10.1053/j.gastro.2021.07.042.

8.Huff JC, Weston WL, Tonnesen MG. Erythema multiforme: a critical review of characteristics,diagnostic criteria, and causes[J]. J Am Acad Dermatol, 1983, 8: 763. DOI: 10.1016/s0190-9622(83)80003-6.

9.Grünwald P, Mockenhaupt M, Panzer R, et al. Erythema multiforme, Stevens-Johnson syndrome/toxic epidermal necrolysis-diagnosis and treatment[J]. J Dtsch Dermatol Ges, 2020, 18(6): 547-553. DOI: 10.1111/ddg.14118.

10.Soares A, Sokumbi O. Recent updates in the treatment of erythema multiforme[J]. Medicina (Kaunas), 2021, 57(9): 921. DOI: 10.3390/medicina57090921.

11.Weston WL. Herpes-associated erythema multiforme[J]. J Invest Dermatol, 2005, 124: xv-xvi. DOI: 10.1111/j.0022-202X.2005.23764.x.

12.Schalock PC, Dinulos JG, Pace N, et al. Erythema multiforme due to Mycoplasma pneumoniae infection in two children[J]. Pediatr Dermatol, 2006, 23: 546. DOI: 10.1111/j.1525-1470.2006.00307.x.

13.Auquier-Dunant A, Mockenhaupt M, Naldi L, et al. Correlations between clinical patterns and causes of erythema multiforme majus, Stevens-Johnson syndrome,and toxic epidermal necrolysis: results of an international prospective study[J]. Arch Dermatol, 2002, 138(8): 1019-1024. DOI: 10.1001/archderm.138.8.1019.

14.Shabahang L. Characteristics of adult outpatients with erythema multiforme[J]. Pak J Biol, 2010, 13(22): 1106-1109. DOI: 10.3923/pjbs.2010.1106.1109.

15.Ahdout J, Haley JC, Chiu MW. Erythema multiforme during anti-tumor necrosis factor treatment for plaque psoriasis[J]. J Am Acad Dermatol, 2010, 62(5): 874-879. DOI: 10.1016/j.jaad.2009.04.048.

16.Vergara G, Silvestre JF, Betlloch I, et al. Cutaneous drug eruption to infliximab: report of 4 cases with an interface dermatitis pattern[J]. Arch Dermatol, 2002, 138(9): 1258-1259. DOI: 10.1001/archderm.138.9.1258.

17.Lichtenstein GR, Loftus EV, Isaacs KL et al. Clinical guideline: management of Crohn's disease in adults[J]. Am J Gastroenterol, 2018, 113(4): 481-517. DOI: 10.1038/ajg.2018.27.

18.李娜, 叶梅. 炎症性肠病生物制剂治疗的前沿进展[J]. 医学新知, 2022, 32(4): 310-320. [Li N, Ye M. Advances in biological agents in the treatment of inflammatory bowel disease[J]. Yi Xue Xin Zhi, 2022, 32(4): 310-320.] DOI: 10.12173/j.issn.1004-5511.202204037.

19.Harbord M, Annese V, Vavricka SR, et al.The first European evidence-based consensus on extra-intestinal manifestations in inflammatory bowel disease[J]. J Crohns Colitis,2016, 10(3): 239-254. DOI: 10.1093/ecco-jcc/jjv213.

20.Wetter DA, Davis MD. Recurrent erythema multiforme: clinicalcharacteristics, etiologic associations, and treatment in a series of 48 patients at Mayo Clinic, 2000 to 2007[J]. J Am Acad Dermatol, 2010, 62: 45. DOI: 10.1016/j.jaad.2009.06.046.

21.Loftus EV Jr, Panés J, Lacerda AP, et al. Upadacitinib induction and maintenance therapy for Crohn's disease[J]. N Engl J Med, 2023, 388(21): 1966-1980. DOI: 10.1056/NEJMoa2212728.

22.Dolinger MT, Rolfes P, Spencer E, et al.Outcomes of children with inflammatory bowel disease who develop anti-tumour necrosis factor-induced skin reactions[J]. J Crohns Colitis,2022, 16(9): 1420-1427. DOI: 10.1093/ecco-jcc/jjac055.

23.Chanchlani N, Lin S, Auth MK, et al. Implications for sequencing of biologic therapy and choice of second anti-TNF in patients with inflammatory bowel disease: results from the IMmunogenicity to Second Anti-TNF therapy (IMSAT) therapeutic drug monitoring study[J]. Aliment Pharmacol Ther, 2022, 56(8): 1250-1263. DOI: 10.1111/apt.17170.

24.Biemans VBC, van der Woude CJ, Dijkstra G, et al. Ustekinumab is associated with superior effectiveness outcomes compared to vedolizumab in Crohn's disease patients with prior failure to anti-TNF treatment[J]. Aliment Pharmacol Ther, 2020, 52(1): 123-134. DOI: 10.1111/apt.15745.

25.Rakowsky S, Papamichael K, Cheifetz AS.Choosing the right biologic for complications of inflammatory bowel disease[J]. Expert Rev Gastroenterol Hepatol, 2022, 16(3): 235-249. DOI: 10.1080/17474124.2022.2036122.

26.Guillo L, D'Amico F, Danese S, et al. Ustekinumab for extra-intestinal manifestations of inflammatory bowel disease: a systematic literature review[J]. J Crohns Colitis, 2021, 15(7): 1236-1243. DOI: 10.1093/ecco-jcc/jjaa260.

27.Fradkov E, Sheehan J, Cushing K, et al. Efficacy of ustekinumab in Crohn's disease with and without concurrent autoimmune skin disease[J]. Inflamm Bowel Dis, 2022, 28(6): 895-904. DOI: 10.1093/ibd/izab201.

28.中华医学会消化病学分会炎症性肠病学组, 中国炎症性肠病诊疗质量控制评估中心. 中国克罗恩病诊治指南(2023年·广州)[J]. 中华消化杂志, 2024, 44: 100-132. [Inflammatory Bowel Disease Group, Chinese Society of Gastroenterology, Chinese Medical Association; Inflammatory Bowel Disease Quality Control Center of China. Chinese clinical practice guideline on the management of Crohn's disease (2023, Guangzhou)[J]. Chinese Journal of Digestion, 2024, 44: 100-132.] DOI: 10.3760/cma.j.cn311367-20240109-00010.

29.中华医学会内分泌学分会, 中国内分泌代谢病专科联盟. 糖皮质激素类药物临床应用指导原则(2023版)[J]. 中华内分泌代谢杂志, 2023, 39(4): 289-296. [Chinese Society of Endocrinology, China Endocrinology and Metabolism Specialist Alliance. Principles for clinical application of glucorticoids(2023 edition)[J]. Chinese Journal of Endocrinology and Metabolism, 2023, 39(4): 289-296.] DOI: 10.3760/cma.j.cn311282-20230116-00029.