Hi you would need to use colour safe shampoo and conditioner. The best one to use is KMS colovitality. it locks in the colour to the hair. It is formulated with IOPS (inside out perfecting system) technology, its also has UV filter in the products which helps to prevent colour fade from the sun and light. The price of the Shampoo is £12.30 and the conditioner is £13.00. They are very concentrated products so you only need to use a size of a 20 pence.