Myth: You should change shampoos regularly because “hair gets used to them”.
May 23rd 2017 by Tony Maleedy.
Not true. But there is an exception. The primary job of a shampoo is to remove dirt and oil from the hair and scalp, this it will do time after time with no diminishing effect, so there is no reason to change your shampoo for this reason. Some shampoos, however, particularly those with high levels of silicone can cause build up on the hair which can influence the texture and manageability of the hair and give it a slightly unnatural feel.
The science bit:
Shampoos that contain a high level of water insoluble silicones such as Dimethicone, a common ingredient in ‘conditioning shampoos’, particularly 2-in-1 shampoos, can build up on hair. Silicones can coat the hair shaft to such an extent that the hair feels weighed down and limp. In some cases the hair can start to feel more like a nylon wig rather than real hair because when you touch your hair your fingers are not coming into contact with the hair itself, but the synthetic silicone which is coating it. This build up of silicone on hair can also be a problem for hairdressers trying to colour a client’s hair because the silicone barrier can interfere with the penetration of colour molecules into the cortex of the hair leaving the new hair colour patchy. Where a build-up of silicone does occur the hair should be washed using a silicone-free shampoo and conditioner. To find one look at the ingredient list and avoid hair products that contain substances such as ‘dimethicone’ and ‘cyclopentasiloxane’, which are likely to interfere with the hair colouring process.