Altitude headache is a common physiological reaction that occurs when a person ascends too quickly to a high elevation. This experience is the most frequent sign of Acute Mountain Sickness (AMS), a condition caused by rapid exposure to reduced atmospheric pressure and lower oxygen availability. The body struggles to adjust to this change, leading to a cascade of symptoms. This article details the specific nature of this pain, its cause, and the necessary response for relief and safety.
The Specific Sensation of an Altitude Headache
The pain felt during an altitude headache possesses distinct characteristics. It is most often described as a throbbing or pounding sensation, typically affecting both sides of the head (bilateral), frequently concentrating in the frontal or temporal regions.
The intensity is usually mild to moderate when it first develops, often within the first day of arrival at a high altitude. The headache is aggravated by physical exertion, movement, or actions that increase head pressure, such as coughing or bending over. The pain is often at its worst upon waking or during the overnight hours.
The pain can last up to five days as the body attempts to acclimatize. If the headache resolves within 24 hours of descending, it confirms the diagnosis of an altitude-related condition.
Accompanying Symptoms and Warning Signs
While the headache is the most common manifestation, it rarely occurs in isolation, presenting with other signs that collectively define Acute Mountain Sickness (AMS). Fatigue and malaise are common, making even simple tasks feel exhausting. Digestive symptoms like nausea, sometimes leading to vomiting, and loss of appetite (anorexia) frequently accompany the head discomfort.
Dizziness and lightheadedness are also common, alongside disturbed sleep patterns, often due to periodic breathing. While these mild symptoms are typical of AMS, their progression can signal the onset of more severe conditions.
Warning signs that require immediate attention include a severe, persistent headache that does not respond to standard pain relievers, along with a significant loss of coordination (ataxia). Inability to walk a straight line is an important test for ataxia, which, along with confusion or altered mental status, suggests High Altitude Cerebral Edema (HACE). Extreme shortness of breath even while resting, or a persistent, wet cough, can indicate High Altitude Pulmonary Edema (HAPE).
Why Altitude Triggers Headaches
The cause of an altitude headache lies in the change in atmospheric conditions experienced at high elevations. At altitudes above approximately 8,000 feet (2,500 meters), the barometric pressure drops, meaning less oxygen enters the bloodstream with every breath. This state of reduced oxygen in the tissues is termed hypoxia.
To compensate for hypoxia, the body attempts to deliver more blood to the brain. This is achieved through cerebral vasodilation, where the blood vessels within the skull widen. This widening increases the volume of blood and the overall pressure inside the skull.
This elevation of intracranial pressure is thought to be the direct cause of the pounding or throbbing sensation characteristic of the altitude headache. The increased pressure may also lead to a minor leakage of fluid, contributing to the mild cerebral edema often associated with AMS.
Relief Measures and Knowing When to Descend
For mild altitude headache symptoms, the intervention is to stop ascending and rest at the current elevation. Maintaining adequate hydration by drinking plenty of fluids is necessary. Simultaneously, avoid substances that can interfere with acclimatization, such as alcohol and excessive caffeine. Over-the-counter nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen or acetaminophen manage the pain.
The principle for managing mild AMS is to not ascend further until the symptoms have resolved. If the symptoms persist or worsen after a day or two of rest, descending to a lower elevation is recommended.
Descent is the only definitive treatment for severe forms of altitude illness and should be undertaken immediately if severe warning signs develop, such as confusion, ataxia, or severe difficulty breathing. A drop of at least 1,000 to 3,300 feet (300 to 1,000 meters) is necessary to achieve significant relief. Medications like dexamethasone can stabilize a person with severe symptoms if immediate descent is impossible, but they are not a substitute for moving to a lower altitude.