Supermarket shelves are full of shampoos for coloured hair making claims such as “helps fight fade out”, “keeps colour looking vibrant”, or “helps prolong colour”. Your hairdresser has probably recommended using an expensive colour-safe shampoo to prevent your colour fading. But do colour-care shampoos make a difference? You might be surprised at our results.

If you spend money on hiding those annoying grey hairs or want to liven up your do with a new hue, you want the colour to last as long as possible. So it makes sense to buy a shampoo specifically for coloured hair … and many of us do. According to figures from the Cosmetic Toiletry and Fragrance Association, Kiwis spend at least $3.1 million a year buying shampoo for coloured hair.

To find which shampoo gives a longer lasting colour, we put 23 shampoos for coloured hair to the test. We also included TRESemme Deep Cleansing Shampoo (a shampoo for all hair types), Johnson’s Baby Shampoo and water.

What we found

Despite the marketing hype, we were surprised to discover washing your hair with water is the best option for maintaining freshly dyed hair. Our test using water – with no shampoo – caused the least colour change after 12 washes.

Allan Blackman, professor of chemistry at Auckland University of Technology, wasn’t surprised by our findings. “Shampoos contain surfactants (which clean your hair) and surfactants are designed to remove both water-soluble and organic-soluble compounds. Hair dyes, while water soluble, are also organic molecules so repeated washing with shampoo will remove small amounts of dye each time,” Professor Blackman says.

Of course, sometimes water won’t cut it when you need to clean your hair. But even then, coloured shampoos didn’t shine. After 12 washes, none performed better than the all-round TRESemme Deep Cleansing Shampoo or the Johnson’s Baby Shampoo.

Paying more for shampoo doesn’t mean a better result. Whether you’re shelling out $10 per 100ml for a salon product or less than $1.50 at the supermarket, all were equivalent at preventing colour fade. If you really want a colour care shampoo, buy on price.

Coloured shampoos share a common ingredient – a UV filter – which slows down the rate the sun bleaches the hair dye. But even figuring in UV protection, none of the tested products appear to offer any specific benefits compared with water.

We asked some of the shampoo companies to provide evidence to support their claims. At time of publication, none had responded.

We say

• It’s the surfactants in shampoos that lead to your hair colour fading. Washing your hair as little as possible minimises colour fade.
• You don’t need a special colour-care shampoo. If you really want one, buy on price.

Report by Belinda Castles.