Whether you’re a natural or a from-the-bottle blonde, chances are you’ll be familiar with the warm, yellow, brassy tones that creep in thanks to UV, pollution and heat damage.

This is where a purple shampoo comes in. Their bright shades might look alarming, but purple and yellow are complementary colours, meaning that they cancel each other out to neutralise brassiness (if you mix complementary colours together they create grey).

It has a similar, though less intense, effect to having a toner applied at a salon. They also work well on grey or white hair.

Purple shampoo shouldn’t replace your regular shampoo; use it a couple of times a week so you don’t overdo it. This also means a bottle will last you far longer, so for those who are usually averse to spending on premium hair products (us included), this is a cost-effective chance to splash out.

Lather and wash as usual, then leave on for a minute before rinsing. Many brands also sell purple conditioner to match, but in our experience they aren’t necessary, so put your money on the shampoo and follow up with your usual conditioner.

These shampoos have been tested by a number of natural and dyed blondes (both highlights and bleach). As well as how well they neutralise yellows and keep colour in good nick, we’ve also looked for scent, lather and the condition of hair after using.

We’ve not included any that overdid it on the colour, leaving an unnatural blue-grey tone, or that dried hair out or weighed it down by leaving residue after rinsing out.

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Bed Head tigi dumb blonde violet toning shampoo, 400ml: £9.95, Feel Unique

This smells sweet, fruity and a little nostalgic, as it reminds us of the strawberry shampoo we used as children. It gives really good shine after washing and reduced flyaways and frizz, even in muggy heat, as well as vastly improving the appearance of months-old highlights. It’s also the best value among the premium offering at 0.05p per ml, thanks to its big 400ml bottle, and the pump means you don’t have to faff with opening it with wet hands.

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Philip Kingsley pure blonde silver brightening daily shampoo, 250ml: £19.50, Philip Kingsley

Those who find the usual dark tones of purple washes alarming will find Philip Kingsley’s clear, only slightly purple shampoo reassuring – and its toning powers are just as strong. It has a fresh scent that is apparently lavender but to us smelled a little like gin (wishful thinking?) and it has a strong lather, so a bottle will last you a long time. The cap on the bottle is really easy to open with wet hands too; its ergonomic shape gives plenty of purchase.

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Kevin Murphy blonde angel wash, 250ml: £22, Cult Beauty

We were totally seduced by the packaging of this shampoo, which is not only sleek and minimalist but is not unlike a wine box, dispensing from the bottom so you no longer have to squeeze and shake to get every last bit of product out. The formula itself is thick and creamy, leaves hair noticeably softer and kept our tester's dyed blonde hair looking true-to-colour long after it would normally fade. The brand also sells 40ml minis if you want to try before splashing out.

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Kerastase blond absolu bain lumiere shampoo: £17.25, Look Fantastic

You can rely on luxury haircare brand Kerastase to make conditioning, strengthening products that really make a difference to your hair’s condition. True to form, blond absolu has a creamy lather that washes effectively but gently, nourishing colour-stressed hair while also knocking back warm, gold tones in bleached locks. We like the twist cap, which is easy to open with wet hands.

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John Frieda sheer blonde colour renew: £5.99, Boots

We’ve been using John Frieda since we first started dying our hair as teenagers for its supreme haircare powers at a quarter of the price of more premium products. Colour renew neutralises brassy tones (though we found it took a few more washes to see results than the one wash the bottle suggests) and lifts dull peroxide without drying and leaves hair softened and weightless.

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IGK mixed feelings leave-in toning drops: £25, Space NK

This, from new cool-girl haircare brand IGK, is a different approach to classic shampoos as it’s an add-in. Dispense 2-4 drops into your usual shampoo and conditioner or to your leave-in styling products for the same cooling purple effect given by shampoos, plus the results are more customisable as you can control how much you add. For the former, you’ll need to use more, 5-10 drops, as you wash it out; there’s a full guide to how much you’ll need to add based on your product and hair colour on the website.

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Sachajuan silver shampoo: £20, Look Fantastic

This is somehow nourishing enough that it revitalises dry colour-treated hair, but not so conditioning that it weighs it down, simply leaving hair super soft and light. Cool blonde tones were restored after a couple of washes in our tester's highlighted hair. It has a good bubbly lather and a fresh citrus scent, and is very thick, almost jelly-like so won’t run between your fingers.

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Davines alchemic shampoo silver: £16.60, Cult Beauty

Davines’ colour-correcting range alchemic has four shampoos: brunette, red, honey (for darker blondes) and silver (for light/peroxide blondes). We found it was a little drying but the toning effect is faultless and paired with a hair mask (try Philip Kingsley or Living Proof) it’s a perfect twice-a-week treat for a hair boost.

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Bleach London pearlescent shampoo: £7.50, Bleach London

Bleach London is literally all about blonde hair, so it’s no surprise that it has a great specialist range. Another alternative to traditional purple shampoos, this still knocks out orange-yellow tones but leaves a warmer, peachy and yes, pearlescent, tone rather than a blue, cooling effect. You’ll have to have pretty bleach blonde hair for it to work, but on the palest silvery shades it’s gorgeous.

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Redken colour extend shampoo blondage: £9.90, Feel Unique

Our tester found this made a visible difference in reducing brassiness after the first wash, extending the amount of time she’d normally go before heading for the salon. It did make hair slightly more tangled than usual but it wasn’t overly drying; paired with leave-in conditioner and a shower comb second time round it worked perfectly.

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The verdict: Purple shampoos

For the best value-per-wash, we’d recommend Bed Head’s dumb blonde. If you're looking to splurge, we’ve been seduced by Kevin Murphy’s great formula and beautiful packaging.

IndyBest product reviews are unbiased, independent advice you can trust. On some occasions, we earn revenue if you click the links and buy the products, but we never allow this to bias our coverage. The reviews are compiled through a mix of expert opinion and real-world testing.