Scientists say they have found a way to restore hair colour with a drug.Prof Karin Schallreuter and her team came across their treatment after discovering the cause of greying - a wear-and-tear process known as oxidative stress.As we age, our hair accumulates hydrogen peroxide, a bleach that robs it of its natural colour.The therapy removes this bleach, the FASEB journal reports. It is not yet clear if it can help avoid going grey.Prof Schallreuter's team, at the University of Bradford in the UK and the University of Greifswald, north-eastern Germany, tested their treatment in a group of patients with vitiligo, a skin condition.Vitiligo causes pale white patches to develop on the skin owing to a lack of the natural pigment melanin.'Numerous remedies'The researchers found their drug, a modified pseudocatalase, repigmented the skin and eyelashes of the vitiligo patients.Gerald Weissmann, editor-in-chief of the FASEB Journal, said: "For generations, numerous remedies have been concocted to hide grey hair, but now, for the first time, an actual treatment that gets to the root of the problem has been developed."While this is exciting news, what's even more exciting is that this also works for vitiligo."Developing an effective treatment for this condition has the potential to radically improve many people's lives."