Most people spend more on colour and extensions than they do on the shampoo and styling products they use on that colour every day. And most of those products contain at least one ingredient that actively works against the investment. This is not a scare article and not a clean-beauty manifesto. It is a practical list from a Denver salon: six ingredients that damage coloured hair and extensions, why they matter, and what to replace them with.

We see the consequences of these ingredients every day in the consultation chair. Clients who cannot understand why their balayage faded in three weeks. Tape-in extensions that slipped a week after install. Gorgeous copper colour that went brassy without explanation. Nine times out of ten the culprit is sitting in their shower at home.

1. Sulfates (SLS, SLES, ammonium laureth sulfate)

Sulfates are the detergents that make shampoo foam up and strip oil from your scalp. They are cheap, they are effective, and they are in most drugstore shampoos. The problem: they are too effective. On coloured hair, sulfates strip colour molecules along with the oil, which is why a fresh balayage looks noticeably lighter and more brass after three or four washes with a sulfate shampoo.

On extensions, the problem is worse. Tape-in adhesive and bead compounds are compromised by surfactants stronger than what extensions are designed for. Sulfate shampoo shortens the life of tape-ins by weeks and makes beaded-row hair brittle at the attachment points.

What to use instead: A sulfate-free colour-safe shampoo. Olaplex No. 4, Redken Acidic Bonding Concentrate, Kerastase Chroma Absolu, and Oribe Shampoo for Beautiful Color are all excellent. Yes, they cost more. The math still works out in your favour because your colour lasts twice as long.

2. Alcohols (SD alcohol, ethanol, isopropyl)

Not all alcohols are bad. Fatty alcohols (cetyl, stearyl, cetearyl) are actually conditioning. Drying alcohols, however, evaporate quickly and take moisture with them. They are common in hairsprays, dry shampoos, and cheaper styling products. In Denver’s already-dry air, drying alcohols turn coloured hair brittle faster than they would in a humid environment.

Check the first three or four ingredients on any hairspray or dry shampoo. If “alcohol denat.” or “SD alcohol 40” is near the top, keep looking. Alcohol-free alternatives exist at every price point now and none of them compromise hold or texture meaningfully.

3. Silicones (especially non-water-soluble ones)

Silicones are controversial because they are both useful and problematic. They do make hair feel smooth and look shiny. The issue with non-water-soluble silicones — dimethicone, cyclomethicone, and cyclopentasiloxane — is that they build up on the hair shaft over time, creating a coating that blocks both conditioner and colour from penetrating. You end up with hair that feels soft but is actually under-nourished and fading faster than it should.

On extensions the build-up problem is compounded because extensions cannot shed buildup the way natural hair can. Within a month of heavy silicone use, tape-ins and beaded rows start looking dull even right after washing.

What to look for: water-soluble silicones (dimethicone copolyol, PEG-modified dimethicones) are fine. Non-water-soluble ones in leave-in products are where the trouble lives. When in doubt, a clarifying wash once a month with a chelating shampoo like Malibu C strips silicone buildup.

4. Avobenzone and other chemical sunscreens (when applied to the face)

This one surprises clients. The sunscreen you put on your face migrates to your hairline and ends. Avobenzone, octisalate, and oxybenzone are particularly problematic because they react with chlorinated and mineral-rich water to oxidise light-coloured hair — turning blondes brassy or orange, especially around the face-frame where the product transfers. Women who notice their blonde goes “off” during summer are often looking at sunscreen transfer, not the sun itself.

Fixes: use a mineral (zinc oxide or titanium dioxide) sunscreen on your face instead of a chemical one. Rinse the hairline quickly before a pool or shower so product does not sit in there. A clarifying wash twice a month during summer also helps.

5. Clarifying shampoos used too often

A clarifying shampoo used monthly is a useful tool. Used weekly, it strips colour as aggressively as a sulfate shampoo does. Clients who are struggling with buildup often over-correct by clarifying every wash, which solves one problem and creates another. Use a clarifying wash once or twice a month maximum. For mid-cycle cleanliness, a sulfate-free clarifier like Living Proof Perfect Hair Day Triple Detox or Redken Detox Hair Cleansing Cream is gentler but still effective.

6. Parabens and formaldehyde-releasing preservatives

This is the one category where the concerns are scalp-health and long-term-safety rather than specifically damaging to colour. Parabens, formaldehyde-releasing preservatives like quaternium-15 or DMDM hydantoin, and MI/MCI preservatives are linked to scalp irritation and allergic contact dermatitis. They are not causing your colour to fade, but if you have a sensitive scalp (especially common in Denver’s dry climate), switching to paraben-free preservatives can reduce the flaking and itching you might not have connected to product.

Most premium professional salon brands have been paraben-free for years. Drugstore brands are catching up but still inconsistent.

How to read a hair-product label in 60 seconds

Ingredients on a label are listed in descending order by volume. The first five or six are what you are actually paying for; the rest are present in small amounts. Three rules: if a sulfate (sodium lauryl sulfate or sodium laureth sulfate) is in the top five of a shampoo, that is a stripping shampoo regardless of its marketing claims. If “alcohol denat.” is in the top five of any styling product, it will dehydrate your hair. And if dimethicone or cyclopentasiloxane is the fourth or fifth ingredient in a leave-in, the product will build up over time.

Marketing language like “colour-safe,” “professional,” and “salon quality” is not regulated and is not a substitute for reading the label. The actual ingredient list is.

Frequently asked questions about hair product ingredients

Is every sulfate bad for coloured hair?

Yes, effectively. Sodium lauryl sulfate, sodium laureth sulfate, and ammonium laureth sulfate all strip colour when used as the primary detergent. Gentler alternatives (sulfosuccinates, glucosides, taurates) are less aggressive but still technically surfactants; you want those as the primary cleansers instead.

Do drugstore colour-safe shampoos actually work?

Some do, some do not. “Colour-safe” is a marketing term without a regulated definition. Read the label: if the first cleanser is sodium lauryl sulfate, the product is not truly colour-safe regardless of the claim on the front. Pantene Pro-V Colour Preserve, L’Oreal Color Vibrancy, and some Garnier Fructis options are genuinely sulfate-free. Most other drugstore “colour-safe” shampoos include sulfates further down the ingredient list.

My shampoo does not foam enough. Is it actually cleaning?

Foam is produced by sulfates. Sulfate-free shampoos foam less because they are using gentler surfactants. Less foam does not mean less clean; it means less aggressive. Lather it into a paste with a small amount of water in your palm before you apply to hair, and you will find it cleans well.

How often should I wash hair with extensions?

Two to three times a week is the sweet spot for most extension types. Every day is too often (the adhesive or bead weakens). Once a week is not enough (oil buildup at the attachment point can loosen tape-ins). Sulfate-free shampoo, cooler water, and patting dry instead of rubbing — that is the routine that keeps extensions looking good for their full lifespan.