Hi. The prescription suggested by your doctor is apt for your concern. You can use it safely as it would not harm your hair. In addition to that you can use an oral vitamin supplement containing zinc, biotin, calcium pantothenate or PABA. These products are safe, so use them without worrying for at least 4-6 months. Premature greying usually is hereditary or due to stress and vitamin deficiencies esp calcium pantothenate deficiency.. Foods rich in protein like soy, lentils, sprouts, meats, liver, eggs along with biotin and selenium rich food like carrots, salmon, sardines, nuts cauliflower induce good hair growth as well as prevent further premature greying. Green leafy vegetables, salads fruits are helpful too. regards