What is fainting? Fainting is temporary loss of consciousness that occurs from an interruption of, or decreased amount of, blood supply to the brain. It may be preceded by the sensation of feeling lightheaded or unsteady, as if you will lose your balance, or a feeling that things are spinning around you. Fainting and dizziness may be accompanied by other symptoms, such as nausea with or without vomiting, perspiration, and trembling. The medical term for fainting is syncope. Blood supplies oxygen to the brain. Fainting occurs when blood is not getting to the brain quickly enough or if there is a deficit of blood. Certain conditions that cause dizziness and loss of consciousness include orthostatic hypotension (drops in blood pressure from standing too quickly), hunger, hypoglycemia (low blood sugar), dehydration, or heart problems. Feelings of anxiety, panic and fear can also result in fainting. Some medications are also associated with fainting or loss of consciousness. These include blood pressure medications, allergy medications, and diabetes medications. Feeling lightheaded and dizzy can be signs of a potentially life-threatening condition, such as a heart attack, stroke, or shock (a severe blood pressure drop). Seek immediate medical care (call 911) if you experience dizziness accompanied by feelings of pain or pressure in your chest, speech problems, shortness of breath, sudden weakness or numbness on one side of the body, chest pain that radiates down the arm or to the jaw, or alterations in vision.