Hair turning white is usually due to a reduction in melanin (the pigment that gives hair its colour), and this is most often related to genetics, ageing, stress, or nutritional deficiencies (like vitamin B12, iron, or copper). Hair colour products such as those from Garnier do not typically cause permanent whitening of hair, but frequent use may damage hair or make existing grey hair more noticeable. Unfortunately, once a hair strand turns white, it cannot naturally become black again. Management focuses on preventing further greying and maintaining healthy hair: eat a balanced diet rich in vitamins and minerals, manage stress, and avoid excessive use of harsh chemical products. You may use safer, ammonia-free hair dyes or natural options like henna for coverage. If greying is sudden or excessive at a young age, it is advisable to consult a doctor to check for nutritional deficiencies or thyroid issues.