BACKGROUNDA silicone allergy can significantly impact the efficacy of ventriculoperitoneal shunt devices used in hydrocephalus treatment. Its clinical presentation often resembles infectious ventriculitis, characterized by altered cerebrospinal fluid (CSF) parameters, including low glucose levels, elevated protein concentrations, and increased white blood cell counts predominantly comprising eosinophils.OBSERVATIONSThe authors report the case of an 18-month-old male who experienced recurrent shunt malfunction linked to CSF changes indicative of infectious ventriculitis. The patient underwent surgeries for suspected infection management. Notably, he exhibited increased eosinophil counts in both blood and CSF, as well as the development of neoformation tissue. This, along with the absence of microbial infection, indicated silicone hypersensitivity. While navigating medical device scarcity, innovative methods were employed to secure a silicone-free valve, markedly improving the patient’s clinical outcome.LESSONSClinicians must be vigilant for silicone allergy in patients with ventriculoperitoneal shunts, particularly when elevated serum eosinophil counts and negative microbiological tests are present. This rare condition demands a multidisciplinary approach for timely diagnosis and management to reduce morbidity, unnecessary surgeries, and healthcare costs. The limited availability of non–silicone-based shunts further complicates management. This case emphasizes the need for considering silicone allergy in differential diagnoses, especially in pediatric patients.https://thejns.org/doi/10.3171/CASE2474