Low blood oxygen, also known as hypoxemia, is a condition where the oxygen level in your arterial blood drops below a normal level, which would be anywhere between 95 and 100 percent saturation, according to the Mayo Clinic. As blood oxygen dips down to 85 and 90 percent, your cells cease to perform as usual, upsetting the function of your organs and tissues. When this happens, you'll inevitably begin to manifest certain signs and symptoms of this lack of oxygen in your blood.

If you had low blood oxygen, you would begin to experience shortness of breath. This particular symptom may start out gradual at first, coming on as an almost unnoticeable change to your respiration, impacting you more during times of physical exertion. But as your blood oxygen saturation falls, this windedness would become more and more pronounced, affecting you even at times of rest.

Since low blood oxygen is essentially depriving your organs of oxygen, you may begin to experience fatigue. And much like the symptom of respiratory disturbance, this indicator will typically come on slowly. You may start out feeling a little more tired than normal. This could then progress into fatigue until you finally feel exhausted or worn out. Sometimes, if your blood oxygen saturation drops rather quickly, this fatigue would hit you suddenly and unexpectedly.

As your blood oxygen saturation falls, the oxygen that actually gets to your brain will unavoidably get less and less. When this happens, certain cognitive functions will be adversely affected and you may begin to experience intermittent episodes of confusion or uncertainty or even disorientation. It all depends on how your brain reacts to this deprivation.

For some people, low blood oxygen will also prompt periodic headaches. Normally, these headaches will come with other symptoms like a shortness of breath, fatigue or confusion. Very rarely will this symptom develop all on its own. It should also be noted that a headache due to low blood oxygen will react to anti-inflammatory medications, such as ibuprofen and acetaminophen, just like any other headache, but these drugs are not remedying your blood oxygen saturation, only this symptom of low blood oxygen.

If you were to experience these symptoms, you should contact a doctor immediately as the low blood oxygen itself could be a symptom of serious condition, like a chronic obtrusive pulmonary disease (emphysema or chronic bronchitis), a lung disease, a heart disease or undiagnosed asthma.