Review of Preexisting Medical Conditions in Persons Traveling to High Altitude, 2025

As the global population grows and access to remote environments expands, travel to high altitude destinations has become increasingly common, now attracting ∼100 million visitors annually. This trend coincides with a population that is increasingly medically complex, emphasizing the importance of understanding how preexisting medical conditions are influenced by ascent to high altitude. This narrative review summarizes the current evidence describing the physiologic and clinical implications of altitude exposure among individuals with chronic medical conditions. A comprehensive literature search was conducted across multiple databases and sources using inclusive keyword and phrase strategies related to high altitude and preexisting medical conditions. All relevant peer-reviewed studies, reviews, and consensus statements were reviewed to ensure a thorough synthesis of available data. The discussion is organized by body system, encompassing cardiovascular, pulmonary, neurologic, metabolic, hematologic, and other relevant conditions. Findings indicate that while many patients with stable, well-managed chronic illnesses can tolerate moderate or even high altitudes, those with advanced cardiopulmonary disease or cerebrovascular pathology face heightened risk and warrant individualized evaluation prior to ascent. This review provides practical, evidence-based guidance to clinicians, expedition planners, and emergency providers caring for high altitude travelers with preexisting conditions. Recommendations emphasize pretravel risk stratification, optimization of chronic disease control, and strategies to mitigate altitude-related complications, supporting safer and more informed participation in high altitude activities.