Ibuprofen is often taken by travelers to high altitude to treat the symptoms of acute mountain sickness such as headache and malaise. However, the blunting of inflammation by ibuprofen may slow the process of acclimatization to altitude, which relies on mediators of inflammation for adjustments in breathing.

The study randomizes healthy subjects to receive ibuprofen or placebo and then ascend to altitude (12,500 feet). Blood cytokines and non-invasive measurements of blood and tissue oxygen levels will be made for 48 hours at altitude. The hypothesis being tested is that subjects receiving ibuprofen will have lower blood and tissue oxygen levels after 48 hours at altitude than will placebo subjects.

The study will begin with 2 days of studies in San Francisco (sea level baseline). Measurements will include non-invasive measurements of blood and tissue oxygen and venous blood draws for cytokine levels.

The altitude part of the study involves ascent to the University of California's White Mountain Research Center Barcroft Laboratory, at 12,500 feet elevation. The subjects will remain at that altitude for at least 48 hours for measurements of oxygenation and blood cytokines.

Inclusion Criteria:

• healthy subjects The group of subjects in this experiment will be composed of healthy adult volunteers, over age 18 and under age 65, of any ethnic group, in good physical and mental health. We expect to enroll approximately 20 subjects. The ethnic groups represented will depend on the ethnicity of those who wish to be subjects, but no ethnic groups will be specifically sought after or rejected.

Exclusion Criteria:

Subjects will be specifically excluded according to the following criteria:

1. History of any clinically significant medical condition, particularly abnormal respiratory, cardiovascular, neurological, hematological, renal or hepatic function. A medical history and physical exam will be performed at the screening session for each subject. We will use this to determine whether the subjects are healthy and without any history of these conditions. No laboratory workup will be required
2. Regular smokers (more than 1 cigarette or cigar per day).
3. Currently active or recently treated systemic or serious local infection.
4. Recent regular use of prescription medications or regular physician care for any significant medical condition.
5. A history of high altitude pulmonary edema or high altitude cerebral edema.
6. Recent exposure to altitude (>8000 ft) in the last month or having slept at an altitude >6000 feet in the last month.
7. Inability to provide written informed consent or to be able to complete the experiment.
8. Pregnancy as determined by a urine pregnancy test if subjects believe they might be pregnant
9. Allergy to non-steroid anti-inflammatory drugs (NSAIDs) or subjects reporting history or symptoms of ulcers or other ibuprofen related contraindications discussed with the screening physician.
10. Heavy coffee drinkers or caffeine users will be advised that they may suffer rebound headache when restricted from caffeinated beverages on measurement days, and asked to carefully consider any continuing participation in the study after abstaining from caffeine during their first sea level measurements.

Deidentified data may be shared with colleagues at other University of California campuses or affiliated academic institutions. No subject identifiers will be included.

To study completion.

De-identified data set only.