Light-headedness and dizziness have a variety of causes. According to WebMD, some causes of lightheadedness include allergies, flu or colds, fevers, diarrhea, vomiting, dehydration, anxiety, stress, hyperventilation, and use of alcohol, tobacco or illegal drugs.
In more serious cases, bleeding inside the body, stroke, heart disease and an extreme drop in blood pressure can cause light-headedness, according to MedlinePlus.
Dizziness often has two symptoms: light-headedness and vertigo. Light-headedness is when one feels faint or feels like passing out, whereas vertigo is the feeling that the world is spinning.
According to Healthline, some possible causes of dizziness include low blood sugar, dehydration, pregnancy, bleeding, caffeine overdose, hypovolemic shock, whiplash and high blood pressure. Other more serious health conditions include menieres disease, epidural hematoma, arteriosclerosis, toxic megacolon and viral gastroenteritis.