Blue shampoo is one of those products that works brilliantly when you use it right and turns your hair a strange shade when you do not. If you have brown or dark blonde hair that keeps going warm and brassy, it is the fix. Here is what it does, how to use it, and how to avoid the mistakes that put people off it.
What does blue shampoo do?
Brown and dark blonde hair tends to turn orange over time. That happens as colour fades and the warm tones underneath start to show through, especially on lightened or highlighted hair. Blue sits opposite orange on the colour wheel, so a blue pigment cancels those orange tones out. The result is a cooler, cleaner brown without the brassiness. It is the darker-hair equivalent of purple shampoo, which does the same job on pale blonde by cancelling yellow.
If you are not sure whether you need blue or purple, we cover exactly that in our blue shampoo versus purple shampoo guide. The short rule: purple for blonde, blue for brunette and dark blonde.
How to use blue shampoo
Wet your hair as normal. Blue shampoo works on damp hair, not dry.
Work a small amount through the mid-lengths and ends where brassiness shows most. You do not need much.
Leave it on. This is the part that controls the result, so read the timing below carefully.
Rinse thoroughly, then follow with conditioner to keep the hair soft.
How long to leave blue shampoo on
Start with two to three minutes and rinse. The longer the pigment sits, the more toning you get, so the exact time depends on how brassy your hair is and how strong the shampoo is. If your hair is very warm, you can build up to five minutes. The safe approach is to under-do it the first time, see the result, and go a little longer next wash if you want more. Leaving it on far too long is what causes the occasional blue or grey cast people worry about, and it is almost always down to timing rather than the product.
How often should you use it?
Once or twice a week is plenty for most people. Blue shampoo is a toning treatment, not your everyday wash, so use your regular shampoo the rest of the time and reach for the blue one when the warmth starts creeping back. On the weeks your colour looks fine, you can skip it entirely.
Can you use blue shampoo on blonde hair?
You can, but it is really made for darker shades. On pale blonde, blue pigment can look too cool or even leave a faint tint, so purple is the better choice there. Blue comes into its own on dark blonde, bronde and brunette hair, including highlights and balayage that have gone warm.
Does blue shampoo damage hair?
No. It deposits a temporary pigment and cleanses like any other shampoo, so it does not damage the hair or lift colour. Some toning shampoos can feel slightly drying because pigment formulas are less moisturising, which is why following with a conditioner or a weekly mask keeps everything soft. You can find blue toning options and their matching conditioners in the toning haircare range.
Use it once or twice a week, keep the timing short, and blue shampoo will hold your colour cool and expensive-looking between salon visits.
