What is dizziness? Dizziness is the sensation of lightheadedness, or the feeling that you might pass out. Dizziness may be accompanied by nausea and vomiting, perspiration or a cold sweat, imbalance, and fainting. Blood supplies oxygen to the brain. Dizziness occurs when blood is not getting to the brain quickly enough, or if there is a deficit in the amount of oxygen in the blood. Lightheadedness can be caused by orthostatic hypotension (a drop in blood pressure after you stand); hunger; common illnesses and infections, such as colds; hypoglycemia (low blood sugar); dehydration; heart problems; or feelings of anxiety and panic. More-serious causes of lightheadedness include severe bleeding, heart attack, and abnormal heart rhythms. People with dizziness are at high risk for traumatic fall injuries. The sensation of things spinning around you, making you feel unsteady or off-balance is known as vertigo, and many people may describe this symptom as dizziness. Vertigo is most commonly caused by a condition known as benign positional vertigo, labyrinthitis (inflammation of the inner ear), Meniere’s disease (inner ear disease that affects balance and hearing), migraines, and decreased blood flow to the cerebellum (the lower portion of the brain that is involved in control of balance). Feeling lightheaded and dizzy can be signs of a potentially life-threatening condition, such as a heart attack, stroke, or shock (severe drop in blood pressure). Seek immediate medical care (call 911) if you experience dizziness accompanied by feelings of pain in your chest, speech problems, confusion or loss of consciousness for even a brief moment, difficulty breathing, severe abdominal pain, severe headache, uncontrolled bleeding, sudden weakness or numbness on one side of the body, or changes in vision.