Treatment for lightheadedness depends on the cause or underlying problem. Treatment may include drinking plenty of water or other fluids (unless the lightheadedness is the result of water intoxication in which case drinking water is quite dangerous). If a sufferer is unable to keep fluids down from nausea or vomiting, they may need intravenous fluids such as Ringer's Lactate. Sufferers should try eating something sugary and lying down or sitting and reducing the elevation of the head relative to the body (for example, by positioning the head between the knees). Other simple remedies include avoiding sudden changes in posture when sitting or lying and avoiding bright lights. Several essential electrolytes are excreted when the body perspires. When people experience unusual or extreme heat for a long time, sweating excessively can cause a lack of some electrolytes, which in turn can cause lightheadedness.
symptom of Hypotension
symptom of Arrhythmia
symptom of Vomiting
symptom of Hypothermia
symptom of Hyperthermia
symptom of Lightheadedness
symptom of Hypoxia 
symptom of Heart failure