Hypoxia is a condition of insufficient O2 for proper organ and brain function


Recognize the symptoms, causes, effects, and corrective actions for hypoxia


  • Hypoxic—inadequate supply (altitude)
  • Hypemic—inadequate transport capacity (CO, some drugs)
    • Smoking at sea level can produce the physiological equivalent of 5-8,000 feet of altitude.
  • Histotoxic—inadequate cellular uptake (EtOH and depressants)
    • 1 oz of alcohol can produce the physiological equivalent of 2,000 feet of altitude.
  • Stagnant—inadequate circulation (medical conditions and load)
  • Effects
    • Causes cognitive deficits such as decreased judgment, euphoria/belligerence, loss of memory or alertness, drowsiness, and unconsciousness (time of useful consciousness PHAK 15-3)
    • Sensory: tunnel vision
    • Motor: lack of coordination, increased reaction time

Instructional aids

None required


  • LiVEDDDHead: Lightheadedness, Visual disturbance, Euphoria, Disorientation, Drowsiness, Dizziness, Headache → all these symptoms are common to lack of O­­2
  • Similar to nitrous oxide buzz
  • Other symptoms listed in RFH and PHAK

Avoidance and recovery

  • Avoid by using supplemental O2 per CFR §91.211 (12,500/14000/15000) or having lower personal limitations (eg, 10000 MSL day/5000 MSL night)
  • IMSAFE checklist: alcohol and some drugs can precipitate hypoxia at lower altitudes
  • Recover by using supplemental O2 or descending at first signs of LiVEDDDHead

Real-life advice and experience

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Additional resources

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