Patients with moderate to severe hidradenitis suppurativa failing adalimumab therapy, or those ineligible to receive it, remain a population with an unmet need. Twenty patients not eligible for adalimumab were randomized to receive 12 weeks of blind treatment with placebo or MABp1, a true human antibody targeting IL-1α. Hidradenitis suppurativa clinical response score at week 12 was the primary endpoint. The primary endpoint was met in 10% and 60% of placebo- and MABp1-treated patients, respectively (odds ratio = 13.50, 95% confidence interval = 1.19-152.51). Clinical efficacy was maintained at 24 weeks in 0% and 40%. Improvement in the visual analog scale was reported by 20% and 85.7%, respectively, of patients failing previous anti-TNF treatment. Ultrasonography showed decreased neovascularization and lesion skin depth in the MABp1 group. MABp1 treatment was associated with decrease of circulating IL-8 and of stimulated production of IL-8 by whole blood. Whole blood production for hBD-2 was negatively associated with changes on ultrasonography in the placebo group but not in the MABp1 group. MABp1 is a promising treatment for patients with hidradenitis suppurativa not eligible for adalimumab. Inhibition of neovascularization and modulation of the production of IL-8 and hBD-2 are suggested mechanisms of action.