Few hair loss are reversible but not all. There could be one or many trigger factors for hair loss. Most common causes are high grade Fever, Nutritional deficiencies, crash dieting or anaemia, thyroid, some medicines like antibiotics, steroids, chemotherapy, anti-hypertensive and anti-coagulant drugs, hormonal pills, Hereditary factor, Irregular food and sleeping habits, Environment and water changes, Environment and water changes, or stress. Try to find out the reason and then plan the treatments.