# What do sulfates actually do in shampoo? | Hair Ingredient Lab

Source: https://hairingredientlab.com/blog/sulfates-shampoo-what-they-do.html

Published September 24, 2026


Sulfates, mainly sodium lauryl sulfate (SLS) and sodium laureth sulfate (SLES), are surfactants: they lift oil and dirt so water can rinse them away. They clean very effectively, which is both the point and the problem. For oily scalps they work well. For dry, curly, color-treated, or sensitive scalps, they can strip too much, and a gentler surfactant system is worth trying.

## The two sulfates on the label

SLS is the stronger, harsher one: excellent degreaser, more likely to irritate eyes and sensitive scalps. SLES is its ethoxylated cousin, meaning it went through an extra processing step that makes it milder while still cleansing well. Most mainstream shampoos use SLES, not SLS, but both get lumped together under "sulfates" on marketing copy. If you want to know what is actually in your bottle, read the ingredient list instead of the front label. The front label saying "sulfate-free" is a claim; the ingredient list is the evidence.

## When sulfates are too much

Signs the cleanser is stronger than your hair needs: a squeaky, stripped feeling after every wash, scalp tightness or flaking that started with a new shampoo, color fading faster than expected, or curls that feel rougher and frizzier than they should. Fine or oily hair often tolerates SLES fine, because the scalp produces enough oil to buffer the cleansing. The mismatch happens when strong surfactants meet hair that has little oil to spare. This is a fit problem, not a toxicity problem: at the concentrations used in rinse-off products, sulfates are considered safe by regulators, including the Cosmetic Ingredient Review panel.

## What "sulfate-free" formulas use instead

Sulfate-free does not mean surfactant-free. These formulas swap in milder cleansers: cocamidopropyl betaine, sodium cocoyl isethionate, sodium lauroyl sarcosinate, or glucoside-based surfactants like decyl glucoside. They lather less dramatically, which some people mistake for cleaning less. They do clean; they just do it more gently. One honest caveat: a very gentle shampoo may not fully remove heavy silicone or butter buildup, which is why people who go sulfate-free sometimes need an occasional clarifying wash with a stronger cleanser. The two ideas work together, not against each other.

## How to choose without the marketing noise

Match the cleanser to the scalp, not to a trend. Oily scalp, heavy styling products, hard water: a sulfate shampoo is a reasonable tool. Dry scalp, tight curls, fresh color, or a history of irritation: try a sulfate-free formula for three to four weeks and compare. Do not judge in one wash; scalps and routines need a few washes to settle. And keep everything else constant while you test, so the shampoo is the only variable. If nothing changes, the cleanser was never the problem.

## What to do this week

Read your current shampoo's ingredient list and find the surfactants, usually near the top. If your hair feels stripped after every wash, try a formula built on betaine or isethionate surfactants for a month. If your scalp is oily and happy with a sulfate shampoo, there is no reason to switch. The label tells you what is in the product. Your scalp tells you whether it matters.

## Frequently asked questions

### Is squalane good for fine hair?

It is one of the best suited oils for fine hair. It spreads thinly, adds slip and shine at very low doses, and rinses out more easily than heavier oils, so it is less likely to flatten or string the hair by midday.

### Does squalane repair damaged hair?

No. It coats the surface and reduces friction, which protects hair from further mechanical damage and improves feel and shine. It does not rebuild internal bonds or protein. Treat claims of repair from any oil as marketing.

### Is squalane the same as squalene?

They are closely related but not the same. Squalene is the natural, unstable molecule found in sebum and plant sources. Squalane is its hydrogenated, stable form used in cosmetics because it does not oxidise and turn sticky or rancid.

### Where does cosmetic squalane come from?

Modern supply is plant based, mainly fermented sugarcane or olive derived. The finished molecule is the same regardless of source. Older shark derived squalene is now rare in mainstream cosmetics.