Altitude sickness, also known as Acute Mountain Sickness (AMS), generally occurs when trekkers are trekking above 2500 m.The onset of altitude sickness and its severity differs from one person to the next. Trekking in higher altitudes means that the air gets thinner, and there is a lack of oxygen. One’s body reacts to the lack of oxygen, and then, people start to suffer from headaches and dizziness.If you start feeling nauseous and dizzy, take some rest. If the symptoms do not go away, you should take a Diamox tablet and head down to the lower region. Therefore, it is essential to include acclimatizing days in your trekking itinerary.