When your body doesn't have enough oxygen, you could get hypoxemia or hypoxia. These are dangerous conditions. Without oxygen, your brain, liver, and other organs can be damaged just minutes after symptoms start.
Hypoxemia (low oxygen in your blood) can cause hypoxia (low oxygen in your tissues) when your blood doesn't carry enough oxygen to your tissues to meet your body's needs. The word hypoxia is sometimes used to describe both problems.