Brain & Nervous System Health Center

Dizziness is a word that is often used to describe two different feelings. It is important to know exactly what you mean when you say "I feel dizzy," because it can help you and your doctor narrow down the list of possible problems.

• Lightheadedness is a feeling that you are about to faint or "pass out." Although you may feel dizzy, you do not feel as though you or your surroundings are moving. Lightheadedness often goes away or improves when you lie down. If lightheadedness gets worse, it can lead to a feeling of almost fainting or a fainting spell (syncope). You may sometimes feel nauseated or vomit when you are lightheaded.
• Vertigo is a feeling that you or your surroundings are moving when there is no actual movement. You may feel as though you are off balance, spinning, whirling, falling, or tilting. When you have severe vertigo, you may feel very nauseated or vomit. You may have trouble walking or standing, and you may lose your balance and fall.

Although dizziness can occur in people of any age, it is more common among older adults. A fear of dizziness can cause older adults to limit their physical and social activities. Dizziness can also lead to falls and other injuries.

It is common to feel lightheaded from time to time. Brief episodes of lightheadedness are not usually the result of a serious problem. Lightheadedness often is caused by a momentary drop in blood pressure and blood flow to your head that occurs when you get up too quickly from a seated or lying position (orthostatic hypotension). Ongoing lightheadedness may mean you have a more serious problem that needs to be evaluated.

Lightheadedness has many causes, including:

• Allergies.
• Illnesses such as the flu or colds. Home treatment of your flu and cold symptoms usually will relieve lightheadedness.
• Vomiting, diarrhea, fevers, and other illnesses that cause dehydration.
• Very deep or rapid breathing (hyperventilation).
• Anxiety and stress.
• The use of tobacco, alcohol, or illegal drugs.

A more serious cause of lightheadedness 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). You may have small amounts of bleeding in your digestive tract over days or weeks without noticing the bleeding. When this happens, lightheadedness and fatigue may be the first noticeable symptoms that you are losing blood. Heavy menstrual bleeding also can cause this type of lightheadedness.

Sometimes the cause of lightheadedness is an abnormal heart rhythm (arrhythmia), which can cause fainting spells (syncope). Unexplained fainting spells need to be evaluated by a doctor. You can check your heart rate by taking your pulse .

Many prescription and nonprescription medicines can cause lightheadedness or vertigo. The degree of lightheadedness or vertigo that a medicine causes will vary.