Choking occurs when the airway to the lungs has been blocked. Two common causes of choking are food blockages and swelling of the larynx. It can be very serious as a sustained period without air is likely to do great damage or be fatal. If the choking is not immediately obvious, signs to look out for include an inability to talk, difficulty breathing, difficulty coughing forcefully, loss of consciousness, and a blue tinge to the skin, lips and nails. Treatment for choking includes performing the Heimlich maneuver, clearing the airway and CPR.