Lightheadedness is a feeling of faintness, as if you are about to black out. 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 in 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.

What Causes Lightheadedness?
Lightheadedness can be caused by numerous medical conditions, some of which can be dangerous - this is why you need to tell your doctor if you have this symptom. Some of the more common causes of lightheadedness include:
-- dehydration from a viral infection, from nausea and vomiting, or from any other cause
-- using tobacco, alcohol, or illicit drugs
-- various prescription drugs
-- orthostatic hypotension
-- vasovagal episodes
-- dysautonomia
-- allergic reactions
-- heart failure
-- cardiac arrhythmias
-- Anemia or blood loss
-- thyroid disease
-- Diabetes