High-altitude sickness is a medical condition that affects travelers when they move from low altitude to high altitude. It is also known as altitude sickness and hypobaropathy. Symptoms of this condition include headache, breathing difficulties, nausea, and dizziness. To avoid high-altitude sickness, travelers must acclimatize themselves for at least 48 hours before traveling to high-altitude destinations. Other synonyms for high-altitude sickness include mountain sickness, altitude illness, altitude disease, altitude stress, and altitude hypoxia. Travelers must be aware of the risks of high-altitude sickness and take necessary precautions before embarking on a trip to a high-altitude destination.