Sulfates in Shampoo: What They Do and Who May Prefer Sulfate-Free

Sulfates in shampoo are often framed as either the reason hair gets truly clean or an ingredient everyone should avoid. Neither answer is complete. Sulfates are effective cleansers. Whether they suit you depends on the whole formula, how much oil and product you need to remove, and how your scalp and lengths feel after repeated use.

For the larger decision framework, start with our guide to haircare ingredients.

What are sulfates in shampoo?

Sulfates in shampoo are cleansing surfactants that help water remove scalp oil, dirt and styling-product residue. They include ingredients such as sodium lauryl sulfate (SLS) and sodium laureth sulfate (SLES). Surfactants have oil-attracting and water-attracting parts that help loosen residue during washing. D’Souza and Rathi (2015) explain that shampoo formulators commonly combine surfactants to adjust cleansing for different hair needs.

Common sulfate surfactants in shampoo, grouped as D’Souza and Rathi classify them:

To spot sulfates on a label, check the full ingredient name. Similar-sounding ingredients are not always sulfates.

Sulfonates are a common example. A sulfonate, such as sodium C14-16 olefin sulfonate, is not a sulfate: it belongs to a different ingredient family and can appear in sulfate-free shampoos. The name alone does not tell you whether a formula will feel mild or strongly cleansing. For more on sulfonates and other non-sulfate cleansers, read What Is Sulfate-Free Shampoo?

What do sulfates do in shampoo?

Sulfates do the main cleansing work. They bind oil and dirt so water can rinse them away, and they produce foam. D’Souza and Rathi (2015) describe lauryl sulfates as popular primary cleansers that work in hard and soft water, produce rich foam and rinse easily. They describe laureth sulfates as good cleansers that are useful for normal-to-dry hair.

So why do some sulfate shampoos feel harsh? Beauty product-development and innovation expert Lorne Lucree says the answer is rarely one ingredient:

“If a consumer perceives a shampoo as “stripping” it could be the type of surfactant, the concentration of surfactants, how it’s blended with secondary surfactants, or that the formula doesn’t have enough conditioning to offset the cleansing.”

— Lorne Lucree, Beauty product-development and innovation expert; from his written RŌZ Q&A, October 2026

Secondary surfactants are milder cleansers blended in to soften the main one. Even when two shampoos contain the same sulfate surfactant, their cleansing feel can differ because the concentration, supporting surfactants and conditioning system are not necessarily the same.

The tradeoff is that a formula can remove more from the hair and scalp than needed. The same review notes that excessively cleansed hair can feel harsh, rough and dull, with frizz and tangling. That is why formulators pair primary cleansers with milder secondary surfactants and conditioning ingredients. Gavazzoni Dias (2015) also describes how cleansing and conditioning ingredients shape the condition and feel of hair.

“The goal is a balancing act: cleanse thoroughly enough without leaving the scalp or strands feeling stripped or dry. A balanced formula is key in a shampoo. You want to avoid that squeaky clean feeling.”

— Mara Roszak, Hairstylist and Founder of RŌZ; lightly edited from interview for clarity

Why do brands use sulfates in shampoo?

Because they clean well and lather. According to D’Souza and Rathi (2015), lauryl sulfates are among the most popular primary cleansers: they remove sebum well, work in both hard and soft water, produce rich foam and rinse out easily. The review notes that normal-hair shampoos commonly use lauryl sulfate as the primary detergent, and that shampoos made to remove styling-product residue rely on strong detergents such as lauryl sulfates.

Foam matters to shoppers, too. The same review says many people equate more foam with better cleaning. In practice, foam mainly helps spread shampoo over the hair and scalp; it is not a measure of how clean the hair gets.

Are sulfates bad, and who may prefer sulfate-free?

Not automatically. Sulfates are effective cleansers, and whether they suit you depends on the whole formula and your hair and scalp. Dry, processed, curly or easily irritated hair and scalps may do better with a gentler wash, and a sulfate-free formula is one way to get it. Oily roots or heavy styling buildup may need stronger cleansing.

Sulfate-free is not automatically gentler, either. Concentration and formulation matter more than the presence or absence of one ingredient. pH, conditioning agents and the amount and blend of active surfactants all shape how gentle a formula is. Sulfate-free shampoos still need surfactants, and those cleansers vary in strength.

“The claim that sulfate-free automatically means gentle needs more context. A shampoo uses a combination of ingredients, and sulfate-free formulas can still provide a thorough cleanse. I judge a shampoo by how the complete formula works for that client’s hair and scalp.”

— Lisa Weller, Salon Owner and Hairstylist at Twirl Salon in San Antonio; verbatim excerpt from her written RŌZ interview, September 2026

For the effects sulfates can have on hair, read Are Sulfates Bad for Your Hair? For what sulfate-free means and how to choose one, read What Is Sulfate-Free Shampoo?

How can you tell whether your shampoo is the cause?

Look at the pattern over several washes, not one. The signs below are reasons to review your shampoo and the rest of your routine, not proof that sulfates are the cause:

• A tight, itchy-feeling or uncomfortable scalp right after cleansing
• Lengths that feel dry, dull, rough or unusually tangled
• Color-treated or bleached hair fading
• Hair that feels less soft after washing or not properly conditioned

To work out whether the shampoo is really the cause, Amanda Riley, owner of Summer Hours Salon in Los Angeles, changes one thing at a time:

“I like to ask clients about their entire routine—how often they wash, what they use afterward, how they style their hair, and what has recently changed. If we suspect the cleanser, we can change that one part of the routine and pay attention to how the hair responds over the next several washes. It’s less about one wash and more about noticing consistent patterns in the hair over time.”

— Amanda Riley, Salon Owner & Stylist, Summer Hours Salon, Los Angeles

Persistent itching, burning, redness or scaling deserves evaluation by a dermatologist rather than an ingredient-label experiment.

Should shampoo go on the scalp or the lengths?

Focus shampoo on the scalp, where sebum and most root-level buildup collect. The lather that runs through the lengths during rinsing is usually enough for routine cleansing. The American Academy of Dermatology also recommends concentrating shampoo on the scalp rather than washing the full length of the hair.

That scalp-first method is central to Mara’s perspective because it separates two jobs: cleanse where oil is produced, then condition the mid-lengths and ends according to how much moisture they need.

Why RŌZ chose a sulfate-free formula for Foundation Shampoo

Mara Roszak’s formulation brief for Foundation Shampoo was specific: sulfate-free cleansing that still produced a satisfying lather and a thorough wash, without the “squeaky clean” post-wash feel she associates with over-cleansing. That is a formulation preference, not a claim that sulfates are universally bad.

Foundation Shampoo uses a blend of non-sulfate surfactants. Mara’s application technique: soak the hair fully, focus shampoo at the scalp, add a little more water before adding more product, work through the back of the head (the thickest part, where buildup collects) and rinse thoroughly. If the first wash is breaking through substantial buildup, a second small cleanse can lather more readily.

The full ingredient list is on the Foundation Shampoo product page. For the conditioning side of the decision, read our guide to silicones in hair products.

The RŌZ Guide is published by RŌZ Hair. This is a commercial recommendation from the brand, not an independent product review.

Sources and reporting

Alongside the dermatology and cosmetic-science reviews below, RŌZ’s August 2026 interview and article edits from Mara Roszak, Hairstylist and Founder of RŌZ, inform the cleansing advice. Lisa Weller, Salon Owner and Hairstylist at Twirl Salon, provided written shampoo-selection answers in September 2026, quoted with permission. Amanda Riley, Salon Owner & Stylist at Summer Hours Salon in Los Angeles, provided written answers in a RŌZ stylist Q&A in October 2026, quoted with permission. Lorne Lucree, a beauty product-development and innovation expert, provided written formulation answers in an October 2026 RŌZ Q&A; his excerpt describes why a shampoo can feel stripping. Surfactant behavior depends on the complete formula, concentration, use pattern and individual scalp.

• D’Souza P, Rathi SK. Shampoo and Conditioners: What a Dermatologist Should Know? Indian Journal of Dermatology, 2015. Surfactant classes, primary and secondary cleansers, foam, and over-cleansing.
• Gavazzoni Dias MFR. Hair Cosmetics: An Overview. International Journal of Trichology, 2015. Cleansing and conditioning ingredients and hair condition.
• The Shampoo pH Can Affect the Hair: Myth or Reality? International Journal of Trichology. Shampoo pH and hair.
• American Academy of Dermatology: Tips for healthy hair. Scalp-focused shampooing.