Comparative Effects of Ustekinumab and Vedolizumab on Alopecia in Ulcerative Colitis: A Systematic Review and Meta-Analysis

Abstract

Alopecia areata (AA) is an autoimmune disorder characterised by patchy hair loss and a significant psychological impact. Although traditionally attributed to Th1-mediated pathways, emerging evidence highlights roles for Th2, Th9, and IL-23 signalling. This study aims to perform a systematic review and meta-analysis comparing ustekinumab (IL-12/23 inhibitor) and vedolizumab (α₄β₇-integrin blocker) regarding alopecia outcomes among patients with ulcerative colitis (UC). Biologic agents such as ustekinumab (IL-12/23 inhibitor) and vedolizumab (α-integrin blocker) are increasingly used for ulcerative colitis (UC), but their dermatologic effects remain uncertain. This systematic review and meta-analysis assesses the influence of these biologics on alopecia outcomes. A comprehensive literature search of major databases through September 2025 identified studies reporting hair loss or regrowth in patients treated with these agents. The number of samples ranged from case-report studies in one patient to systematic reviews of studies in more than 2200 patients. Data extraction included demographics, interventions, and outcomes, with pooled analyses conducted using random-effects models. Bias was evaluated using the MINORS tool. Eighteen studies met the inclusion criteria, encompassing case series, cohort studies, and systematic reviews. Ustekinumab showed variable effects, ranging from substantial hair regrowth to paradoxical alopecia, particularly in pediatric patients. Vedolizumab outcomes were similarly inconsistent, with reports of both new-onset alopecia and improvement in skin manifestations. Pooled analysis indicated that 65.5% of patients achieved hair regrowth, and active therapy significantly increased the odds of attaining a SALT score ≥50 (OR = 3.05). Adverse events were mostly mild, while relapse remained common, especially with topical immunotherapy. In conclusion, ustekinumab and vedolizumab exhibit heterogeneous effects on alopecia in UC patients, ranging from disease worsening to meaningful regrowth. While biologics may have therapeutic potential in select cases, their cutaneous effects require further clarification through large, well-designed randomised trials.