Lightheadedness or dizziness can have severe underlying causes. If you frequently experience lightheadedness, you need to get the possible causes diagnosed.

Causes
Low Blood Pressure: When the blood pressure of a person drops significantly, there is a temporary shortage of blood to the brain, as adequate oxygen-rich blood does not reach the brain. This affects normal functioning of the brain, and hence, the person feels dizzy and lightheaded. Most of the time, it is observed that low blood pressure is a side effect of Hypertension medications. When the blood pressure lowers, other symptoms like sweating, nausea, vomiting, chest pain, etc., are also observed.

Low Blood Sugar: Sometimes, the sugar level in the blood drops suddenly. This is known as hypoglycemia. The inadequate supply of glucose results in temporary impaired function of the brain, which results in lightheadedness and sweating. Although common in diabetics, it can also be observed in case of non-diabetics.

Cardiac Arrhythmia: Cardiac arrhythmia is the abnormal heart muscle contraction, i.e., irregularity in the heart beats. When the symptoms of lightheadedness occur in recurrent episodes, there is a high possibility of the presence of heart related illnesses. Sometimes, it can also be a symptom of a heart attack.

Anemia: When a person has less amount of hemoglobin in blood, he is said to suffer from anemia. Anemia occurs when the red blood cell (RBC) count of blood decreases. As hemoglobin carries oxygen in the blood, lack of hemoglobin results in reduced amount of oxygen in the blood, which can result in lightheadedness.

Alcoholism: When a person consumes alcoholic drinks, his blood sugar level falls too low, which can result in hangover symptoms like dizziness and Headaches.