Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 24 6 2025 10 29 741 748 Parastoo Shakerin Immunology, Asthma and Allergy Research Institute, Tehran University of Medical Sciences, Tehran, Iran Raheleh Shokouhi Shoormasti Immunology, Asthma and Allergy Research Institute, Tehran University of Medical Sciences, Tehran, Iran AND Pediatrics Center of Excellence, Children's Medical Center Hospital, Tehran University of Medical Sciences, Tehran, Iran Mohammad Reza Fazlollahi Immunology, Asthma and Allergy Research Institute, Tehran University of Medical Sciences, Tehran, Iran AND Pediatrics Center of Excellence, Children's Medical Center Hospital, Tehran University of Medical Sciences, Tehran, Iran Mahsa Jafari Immunology, Asthma and Allergy Research Institute, Tehran University of Medical Sciences, Tehran, Iran AND Pediatrics Center of Excellence, Children's Medical Center Hospital, Tehran University of Medical Sciences, Tehran, Iran Mona Delkhah Department of Flow Cytometry, Children’s Medical Center Hospital, Tehran University Medical Sciences, Tehran, Iran Parichehr Bahraini Immunology, Asthma and Allergy Research Institute, Tehran University of Medical Sciences, Tehran, Iran Leila Moradi Immunology, Asthma and Allergy Research Institute, Tehran University of Medical Sciences, Tehran, Iran AND Pediatrics Center of Excellence, Children's Medical Center Hospital, Tehran University of Medical Sciences, Tehran, Iran Maryam Mahloojirad Immunology, Asthma and Allergy Research Institute, Tehran University of Medical Sciences, Tehran, Iran Masoud Movahedi Department of Immunology and Allergy, Children's Medical Center Hospital, Tehran University of Medical Sciences, Tehran, Iran Homa Sadri Non-communicable Diseases Research Center, Alborz University of Medical Sciences, Karaj, Iran Morteza Fallahpour Department of Allergy and Clinical Immunology, Rasool-e-Akram Hospital, Iran University of Medical Sciences, Tehran, Iran Alireza Shafiei Department of Pediatrics, Bahrami Hospital, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Fariborz Zandieh Immunology, Asthma and Allergy Research Institute, Tehran University of Medical Sciences, Tehran, Iran Marzieh Tavakol Non-communicable Diseases Research Center, Alborz University of Medical Sciences, Karaj, Iran Mohammad Tajdini Immunology, Asthma and Allergy Research Institute, Tehran University of Medical Sciences, Tehran, Iran Zahra Pourpak Immunology, Asthma and Allergy Research Institute, Tehran University of Medical Sciences, Tehran, Iran AND Pediatrics Center of Excellence, Children's Medical Center Hospital, Tehran University of Medical Sciences, Tehran, Iran 2024 11 25 2025 05 18 The risks associated with in vivo tests in the diagnosis of immediate drug hypersensitivities result in evaluating alternative in vitro tests, such as the Basophil Activation Test (BAT). This pilot study aimed to set up a BAT and compare it with a specific Immunoglobulin E (sIgE) assay for penicillin G and Ibuprofen in patients with immediate hypersensitivity to β-lactams or nonsteroidal anti-inflammatory drugs (NSAIDs). Eleven subjects with a clear history of immediate hypersensitivity to one of the β-lactams (n=5), the NSAIDs (n=3), or both (n=3) entered this study. BAT and sIgE assays were performed regarding the patient’s history. The most frequent manifestations were angioedema, shortness of breath, urticaria, and nausea. Eight patients had anaphylactic reactions. The results presented a positive BAT for penicillin G and one for Ibuprofen. Moreover, three patients with a history of the β-lactams reaction demonstrated positive sIgE to β-lactams in the ImmunoCAP. Despite a lack of agreement between the positive results of the BAT and sIgE assay, five patients were identified by one of these methods. Despite positive BAT and sIgE results in two and three patients, respectively, the risks, high cost, and time-consuming nature of drug challenges render these tests valuable for reducing the number of patients who are candidates for a drug challenge. https://ijaai.tums.ac.ir/index.php/ijaai/article/view/4256 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/4256/2240