Prevalence and Risk Factors of Heat-Related Illness Among Pilgrims During the Hajj Season 2024: A Cross-Sectional Study

Heat-related illnesses (HRIs) remain a significant health concern during mass gatherings (MGs), where high temperatures and physical exertion exacerbate physiological stress. This study examines the clinical spectrum, management practices, and treatment outcomes of HRIs among pilgrims during the 2024 Hajj season, to inform public health responses and mitigation strategies. A cross-sectional study was conducted across nine healthcare facilities in Makkah and the Mashaer region during the 2024 Hajj. Data were retrospectively extracted from medical health care facilities registries using a standardized form to capture demographic characteristics, clinical presentation, management interventions, and in-hospital outcomes of patients diagnosed with heat-related illness. Of the 2,785 screened patients, 2,551 had complete clinical records, and 1,576 met the diagnostic criteria for heat exhaustion or heatstroke, with outcome data available. Most of the patients were male (1,171; 74.3%), with nearly half aged 60 years or older (776; 49.2%) and a large proportion aged 39–59 years (693; 44.0%). The majority were non-Saudi pilgrims (1,419; 90%), primarily from Arab countries, with 793 (50.3%) from these regions. A total of 1,094 patients (69.4%) had no prior history of HRIs. Common symptoms included altered mental status in 635 (40.3%) patients, dizziness in 486 (30.8%), and management interventions included intravenous fluid administration in 569 cases (36.1%) and the application of cooling measures in emergency settings for 1,105 patients (70.1%). The overall mortality rate was 77 (4.9%) cases. Intensive care unit (ICU) admission and elevated lactic acid levels were significantly associated with poor outcomes. Heat-related illness during the Hajj remains a major public health concern, with a substantial clinical burden and potentially severe outcomes. Early recognition, timely intervention, and targeted education are essential for high-risk groups. Strengthening frontline preparedness and resource deployment is crucial to reducing its potential impact.