When we get cold, our lips and extremities often turn blue. This color of the skin may also be a symptom of asthma. However, in the case of asthma, this is a troublesome condition with dangerous consequences. The depreciation of oxygen is the most common reason for the particular parts of the human body to go blue. If the patient is lucky, a blue skin can be a sign of high altitudes. Severe heart illness is the worst outcome.