There are a number of medical reasons why somebody would be passing out or suffering from light-headedness but it is serious enough that a doctor should be consulted to diagnose to find out what the problem is. Passing out is a common complaint in people who have low blood pressure. When your blood pressure is low, not enough blood filled with oxygen is being delivered to the brain, and its function can be affected. The reason you would pass out is because the brain blood supply is decreased too much. In addition to passing out and feeling light headed associated symptoms may include sweating, nausea, vomiting, and shortness of breath and chest pain. Low blood pressure may be the result of underlying illness or disease or it may just be a normal physiological condition. Other reasons for passing out could be a lack of circulation of oxygen or more seriously a blood clot. There could be a lack of circulation normally through dehydration which occurs with infections that cause vomiting and diarrhoea and other fevers. Light-headedness is a feeling that you are about to faint or pass out. It has many simple causes such an allergic reaction to something you have used or just a normal illness such as the flu and home treatment of these symptoms will usually relieve these feelings. A more serious cause of light-headedness is bleeding. Most of the time, the location of the bleeding and the need to seek medical care are obvious. But sometimes bleeding is not obvious (occult bleeding). When this happens, light-headedness and fatigue may be the first noticeable symptoms that you are losing blood. A form of heavy menstrual bleeding also can cause this type of light-headedness. Anxiety and stress are also reasons for passing out or light-headedness.
