High altitude can cause sinus problems, but the discomfort is not due to infection. It arises primarily from the physical change in the surrounding environment, specifically the drop in atmospheric pressure as elevation increases. Sinuses are air-filled cavities within the bones of the face and skull that normally produce mucus. When the body moves to a higher elevation, the air trapped inside these cavities reacts to the external change, leading to symptoms that can feel like a sinus issue.
The Impact of Barometric Pressure Changes
The core mechanism behind altitude-related sinus issues is Boyle’s Law, which describes the inverse relationship between the pressure and volume of a gas. As a person ascends to a higher altitude, the barometric pressure of the surrounding atmosphere decreases. This reduction in external pressure causes the fixed volume of air trapped inside the sinus cavities to expand.
Normally, the sinuses are able to equalize this pressure through small drainage pathways called ostia, which connect the cavities to the nasal passages. If the mucosal lining is already swollen due to a cold, allergies, or an infection, these openings can become blocked. When the expanding air cannot escape, it creates a positive pressure differential against the sinus walls, leading to significant discomfort.
Conversely, during a rapid descent, the atmospheric pressure quickly increases, causing the air within the sinuses to contract. If the ostia remain blocked, air cannot flow into the sinus cavity to equalize the pressure, creating a negative pressure environment. This negative pressure can cause the soft tissue lining of the sinuses to swell and become engorged, which further intensifies the pain.
Recognizing Symptoms of Altitude-Related Sinus Issues
The condition resulting from this pressure imbalance is often called barosinusitis or sinus barotrauma. Symptoms typically manifest as sharp or severe pain and pressure concentrated over the affected sinus cavities, most commonly the frontal sinuses located in the forehead. This intense pressure can radiate, sometimes causing pain between and behind the eyes or even into the upper teeth if the maxillary sinuses are involved.
A severe headache that worsens during ascent or descent is a common sign, often accompanied by a feeling of fullness or congestion. In significant cases of barotrauma, the patient may experience a nosebleed, known as epistaxis, which can be the sole symptom during an ascent.
Strategies for Prevention and Relief
Preventing altitude-related sinus issues focuses on ensuring the ostia remain open to allow for pressure equalization during elevation changes. A primary preventative measure is the use of decongestants, such as pseudoephedrine, taken orally about 30 minutes before beginning an ascent or descent. These medications work by constricting blood vessels, which helps to shrink the swollen mucosal lining and keeps the sinus openings clear.
Hydration is important, as dry air at high altitudes and in airplane cabins can thicken mucus and irritate the nasal passages. Travelers should begin increasing their water intake 24 to 48 hours prior to a trip and continue to use a saline nasal spray frequently. Avoid traveling to high altitudes when already suffering from an upper respiratory tract infection or severe allergies, as this congestion increases the risk of barosinusitis.
During an ascent or descent, active pressure equalization techniques can provide relief. The Valsalva maneuver involves gently pinching the nostrils shut and attempting to exhale through the nose, which forces air into the sinus and middle ear spaces. Chewing gum, swallowing, or yawning can also help to stimulate the muscles that open the passageways, allowing the pressure differential to resolve. If symptoms become severe despite these efforts, a gradual descent to a lower altitude can often provide immediate relief.