If you have brown hair that's been coloured, highlighted or bleached, you've probably noticed unwanted brassy, orange or warm tones creeping in over time. Blue shampoo is one of the most effective solutions — but there's a lot of confusion about what it actually does and whether it works on brown hair. Here's everything you need to know.
What Is Blue Shampoo?
Blue shampoo is a colour-depositing shampoo that contains blue and purple pigments designed to neutralise warm, brassy and orange tones in hair. It works on the same principle as purple shampoo — but where purple shampoo is formulated for blonde and silver hair, blue shampoo is specifically designed for brunettes and brown hair.
The science behind it is simple. On the colour wheel, blue sits directly opposite orange. When you apply blue-toned pigments to hair with orange or brassy undertones, the two colours cancel each other out — leaving hair looking cooler, richer and more vibrant.
Why Does Brown Hair Go Brassy?
Brassiness in brown hair happens for several reasons. When you colour or lighten brown hair, the natural warm pigments in the hair — red and orange — are the last to be lifted. If the lightening process doesn't go far enough, these warm tones remain and become more visible over time.
Sun exposure, heat styling, hard water and washing hair frequently all accelerate the process, causing colour to fade and warm tones to emerge. Even natural brunettes can experience brassiness as their hair colour fades or changes with age.
Does Blue Shampoo Actually Work on Brown Hair?
Yes — genuinely and noticeably, when used correctly. Blue shampoo won't dramatically change your hair colour, but it will visibly reduce brassiness and orange tones, leaving brown hair looking cooler, deeper and more freshly coloured.
The key word here is neutralise rather than remove. Blue shampoo tones down warmth rather than eliminating it entirely. For heavily brassy hair you may need a combination of blue shampoo and a professional toning treatment, but for regular maintenance it's one of the most effective tools available.
At The Cosmetologists our professional team recommends blue shampoo as part of a regular colour maintenance routine for anyone with coloured, highlighted or natural brown hair that tends toward warmth.
Blue Shampoo vs Purple Shampoo — What's the Difference?
This is the most common question we get asked. The difference comes down to the tones each one neutralises:
Purple shampoo neutralises yellow and golden tones — it's designed for blonde, platinum, silver and grey hair where yellow brassiness is the main concern.
Blue shampoo neutralises orange and red-brown tones — it's designed for brunettes, brown hair and darker highlighted hair where warmth and orange brassiness are the issue.
If you have brown hair with highlights, you may benefit from both — using blue shampoo on your roots and lengths where your natural brown shows through, and purple shampoo on your highlighted sections.
At The Cosmetologists we stock a full range of professional toning shampoos for both blonde and brunette hair in our Silver and Purple Toning collection.
How to Use Blue Shampoo on Brown Hair
Getting the best results from blue shampoo comes down to application technique and timing. Here's exactly how to use it:
Step 1 — Wet your hair thoroughly with warm water.
Step 2 — Apply the blue shampoo generously from root to tip, making sure every section is coated. Don't be sparing — full coverage is essential for even toning.
Step 3 — Work the shampoo into a lather and leave it on for 3–5 minutes for a subtle tone reduction, or up to 10–15 minutes for stronger results on heavily brassy hair.
Step 4 — Rinse thoroughly with cool water. Cool water helps seal the cuticle and lock in the toning effect.
Step 5 — Follow with a nourishing conditioner to restore moisture — toning shampoos can be slightly drying with frequent use. Olaplex No.5 or Moroccanoil Hydrating Conditioner are both excellent choices.
How often should you use it? Most brunettes get the best results using blue shampoo once or twice a week, alternating with their regular shampoo. Using it too frequently can make hair look ashy or dull — the goal is cool and vibrant, not grey.
Can You Leave Blue Shampoo on Too Long?
Yes — leaving blue shampoo on for too long can deposit too much pigment and give hair a slightly grey or bluish tint. This is temporary and will wash out with regular shampooing, but it's worth being cautious the first time you use it.
Start with 3–5 minutes and assess the result before going longer. Everyone's hair is different — porosity, existing colour and how brassy your hair is will all affect how quickly the pigment deposits.
Best Products for Toning Brown Hair
At The Cosmetologists we stock a range of professional toning products for brunettes:
For blue shampoo and cool brunette toning — browse our Silver and Purple Toning collection for professional options from brands including milk_shake and REF Stockholm.
For overall colour protection and vibrancy — Color WOW Color Security Shampoo is outstanding for colour-treated brown hair, protecting against fading while keeping hair smooth and glossy. Shop Color WOW →
For damaged or over-processed brunette hair — Olaplex No.4 Bond Maintenance Shampoo repairs while you wash, making it ideal for brown hair that's been coloured or lightened. Shop Olaplex →
For deep nourishment alongside toning — Kérastase Chroma Absolu or Reflection range is specifically formulated for colour-treated hair, maintaining vibrancy and shine between salon visits. Shop Kérastase →
Blue Shampoo for Brown Hair — Our Verdict
Blue shampoo works and is genuinely one of the most effective at-home colour maintenance tools for brunettes. Used correctly once or twice a week it will keep brown hair looking cooler, richer and more vibrant between salon visits.
The key is timing — start with 3–5 minutes and adjust based on your hair's response. Pair it with a good conditioner to maintain moisture, and combine with a bond-building treatment like Olaplex for the best overall results.
If you're unsure which toning products are right for your specific hair colour and concerns, our professional team at The Cosmetologists in Hull is always happy to advise. Call us on 01482 692703 or visit us at 499 Anlaby Road, Hull.
Shop all toning products → Shop Color WOW → Shop Olaplex →
Related Guides
Dealing with damaged or over-processed hair alongside brassiness? Read our guide to the Best Products for Bleached and Damaged Hair — Olaplex, K18 or Kérastase.
Want to protect your colour while styling? See our Complete Olaplex Guide for the best colour-safe routine.
