What Causes Lightheadedness?

Lightheadedness is a feeling of faintness or wooziness, as if you are about to black out. Another term for lightheadedness is presyncope.

Lightheadedness can occur in distinct episodes, or it can be persistent, and it can be very mild or quite severe. Severe lightheadedness may be accompanied by other symptoms such as sweating, feeling overheated, buzzing in the ears, partial blindness (especially feeling as if you are looking through a tunnel), nausea or vomiting. Lightheadedness usually occurs when people are the upright position (standing or sitting), and can often be improved by lying down.

Episodes of lightheadedness can be followed by an actual fainting episode, also known as syncope.

Lightheadedness should always be brought to your doctor’s attention, especially if it is recurrent or severe.

A man feeling lightheaded with his eyes closed and fingers to his brow
Nicola Katie / Getty Images

Is Lightheadedness the Same as Dizziness?

Lightheadedness is one type of dizziness.

When doctors hear a patient say they are experiencing "dizziness," they know (or should know) that they have a job ahead of them. Because "dizziness" can mean several different things — and it's very important for the doctor to sort out which of these different things is actually happening to their patient.

When people say they are having dizziness, they usually mean one of three things. 

They may mean that they are having vertigo. Vertigo is a sensation of motion when there is no motion. It is often described as the room spinning, or a tilting or whirling sensation. Vertigo is an important symptom that has its own list of possible causes, and it always needs to be evaluated. But it's different from what doctors mean by lightheadedness.

Another symptom that may be reported to the doctor as dizziness is disequilibrium — a sense of imbalance or unsteadiness that usually occurs when walking. Disequilibrium is most commonly due to problems with the nervous system or the musculoskeletal system. Depending on the cause, it may also be accompanied by actual lightheadedness. Again, disequilibrium is an important symptom that needs an evaluation, but it too is different from lightheadedness. 

Lightheadedness, in contrast, is faintness or wooziness, a feeling of nearly blacking out. It is often accompanied by other symptoms, most commonly flushing, sweating, nausea, pallor, or visual disturbances, and often improves if you lie down. 

So if you tell your doctor you have had dizziness, you will need to describe as carefully as you can what, exactly, you mean by “dizziness.”

What Causes Lightheadedness?

Lightheadedness can be caused by numerous medical conditions. Often, the symptom of lightheadedness means that the brain is not getting all the blood flow it needs at that moment — and it is always dangerous for the brain not to get its blood flow. This is why you need to tell your doctor if you have this symptom.

Some of the more common causes of lightheadedness include:

How Is Lightheadedness Evaluated?

Because lightheadedness has so many potential causes, and because some of them are serious medical conditions, your doctor will need to do a careful evaluation to sort out the potential causes. In most cases, the cause turns out to be fairly obvious once the doctor focuses his or her attention on the problem.

The most important step for your doctor to take in evaluating lightheadedness is to listen carefully to your description of the symptoms, asking strategic questions along the way, and then to do a careful physical examination. 

It is especially important for the doctor to ask about a history of heart disease, cardiac arrhythmias, or symptoms of palpitationschest pain, or shortness of breath. Any of these may indicate a cardiac cause, an obvious source of concern. 

If a heart problem is suspected, the doctor will probably want to do some cardiac testing — certainly an electrocardiogram, and likely an echocardiogram.

However, the most common causes of lightheadedness are dehydration and vasovagal episodes. For these conditions, a careful medical history and physical exam may be the only evaluation that is needed in order to recommend treatment.

If the cause is suspected to be related to neurological disease, diabetes, thyroid disease, or an allergic reaction, specific testing will be necessary to pin down the final diagnosis.

How Is Lightheadedness Treated?

The treatment of lightheadedness depends completely on the underlying cause. Because the range of disorders that can produce lightheadedness is so broad, the list of potential treatments is vast.

However, for most people who experience lightheadedness, in whom the cause is dehydration or vasovagal episodes, the treatment will consist mainly of learning to avoid the situations which will tend to reproduce the symptoms.

A Word From Verywell

Lightheadedness — a feeling of faintness — is usually a transient symptom, whose cause after a full medical evaluation is fairly easy to diagnose, and which can usually be avoided in the future. However, sometimes this symptom is a harbinger of a dangerous or even potentially lethal underlying cause. 

For this reason, anyone who experiences an episode of significant lightheadedness should be evaluated by a medical professional.

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