Hi, Premature greying of hairs also called poliosis is tough condition to be treated. There may be some cause. Genetic tendency,stress,vitamin deficiencies, anaemia,thyroid and other hormanal disorders..etc. You should be investigated to find out some cause. External causes may be sun exposure, pollutants, shampoo..etc may be kept in mind. PABA containing tab may be taken for few months to few years. Calcium penthotenate is other drug to be used. Melitane gel like altris gel may be applied twice a day for long time may be helpful. You consult dermatologist for perfect diagnosis and treatment. Thanks. Dr. Ilyas Patel MD