Do COSMOS Certified Shampoos Contain Sulfates?

COSMOS certifies where an ingredient comes from and how it is made, not whether the word sulfate is on the label. Why SLES is banned, why Sodium Coco-Sulfate is not.

NUDA certified shampoo bottle with its INCI ingredient list

Yes, many of them do. COSMOS certifies where an ingredient comes from and how it was made, not whether the word "sulfate" appears on the label. Sodium Coco-Sulfate, derived from coconut oil, is permitted under the standard and appears in plenty of certified shampoos. SLES is not permitted, for a reason that has nothing to do with the word itself.

This confuses a lot of people, including several published lists that state certified shampoos are "sulfate free". That is not what the standard says. Here is what it actually regulates.

What COSMOS Actually Prohibits

The COSMOS standard governs three things: the origin of raw materials, the chemical processes allowed to transform them, and the environmental impact of the result. It publishes a list of permitted processes rather than a list of banned marketing words.

Among the prohibited processes is ethoxylation, which uses ethylene oxide. That single rule removes a large family of common cosmetic ingredients: PEGs, most polysorbates, and Sodium Laureth Sulfate (SLES). Also excluded are petrochemical derivatives, silicones, parabens and synthetic fragrance.

Note what is not on that list: sulfation. Sulfating a fatty alcohol is a permitted process when the fatty alcohol comes from a natural source. That is the whole reason the two ingredients below end up on opposite sides of the line.

Why SLES Is Out and Sodium Coco-Sulfate Is In

  SLES (Sodium Laureth Sulfate) Sodium Coco-Sulfate
Source Commonly petrochemical or palm derived Coconut oil fatty alcohols
Process Ethoxylation, then sulfation Sulfation only
Ethylene oxide involved Yes No
Permitted under COSMOS No Yes

The deciding factor is ethoxylation. It is a process that can leave trace contaminants, which is why the standard excludes it outright rather than setting a threshold. The word "sulfate" plays no part in the decision.

Is Sodium Coco-Sulfate Just SLS With a Nicer Name?

This is the fair question, and it deserves a direct answer rather than a dodge.

The two are chemically related. Sodium Coco-Sulfate is produced by sulfating the mix of fatty alcohols found in coconut oil, and that mix includes lauryl alcohol, the same chain that forms Sodium Lauryl Sulfate. So SCS contains a proportion of what is, chemically, SLS, alongside longer chains such as myristyl and cetyl.

The claimed practical difference is that the longer chains raise the average molecular size, and larger molecules penetrate the skin less readily, which would make the blend less irritating. That reasoning is plausible and widely repeated, but the published evidence comparing the two directly is limited. Anyone telling you the difference is dramatic is going beyond what the data supports.

What is not in dispute: SCS is coconut derived, is not ethoxylated, and is permitted under COSMOS. It is a real cleansing surfactant, and it can leave a tight feeling if a formula is not buffered with milder co-surfactants.

What "Sulfate Free" Actually Tells You

Very little, on its own. It is a claim about one ingredient family, not about the quality of a formula. A shampoo can be sulfate free and still contain silicones, synthetic fragrance and petrochemical emollients. We go into that in more detail in does sulfate free shampoo actually clean.

It is also a claim with no legal definition, which is exactly the pattern behind most beauty label language. The same applies to "clean", "natural" and "non-toxic", covered in how to spot greenwashing in hair care.

What to Check Instead

  • The full INCI list, not the front of the bottle. It is ordered by concentration and standardised across brands.
  • Which surfactants are actually present, and whether harsher ones are buffered with milder co-surfactants such as Coco-Glucoside or Cocamidopropyl Betaine.
  • Whether a third party certified it, and under which standard. What ECOCERT COSMOS certification means covers what the audit involves, and COSMOS Natural versus COSMOS Organic explains the two tiers.
  • How your scalp responds, which is the only test that accounts for you specifically.

Where We Stand

Our shampoos contain Sodium Coco-Sulfate, and we do not describe them as sulfate free. They are certified under the ECOCERT COSMOS standard, which permits that ingredient and prohibits the ethoxylated one. What we can accurately say is that they contain no SLS or SLES, and the full INCI for each is published on its product page so the claim is checkable rather than trusted.

The colour care shampoo is one example: Sodium Coco-Sulfate buffered with Coco-Glucoside and Cocamidopropyl Betaine, with aloe leaf juice as the base. Saying so is more useful than a claim that sounds cleaner and explains less.

Related reading

Frequently asked questions

Do COSMOS certified shampoos contain sulfates?
Many do. COSMOS certifies the origin of an ingredient and the process used to make it, not whether the word sulfate appears on the label. Sodium Coco-Sulfate, derived from coconut oil, is permitted under the standard. Sodium Laureth Sulfate is not, because it requires ethoxylation, a process the standard prohibits.
Why is SLES banned under COSMOS but Sodium Coco-Sulfate allowed?
Because of ethoxylation. SLES is made by ethoxylating and then sulfating a fatty alcohol, and ethoxylation uses ethylene oxide, which COSMOS prohibits outright. Sodium Coco-Sulfate is only sulfated, with no ethoxylation step, and comes from coconut oil, so it meets the standard.
Is Sodium Coco-Sulfate the same as SLS?
They are chemically related. Sodium Coco-Sulfate is made from the mix of fatty alcohols in coconut oil, which includes the lauryl chain that forms SLS, alongside longer chains. The larger average molecule is said to make it less irritating, but published evidence comparing the two directly is limited, so the difference should not be overstated.
Does sulfate free mean a shampoo is better?
Not on its own. It describes one ingredient family and says nothing about the rest of the formula. A sulfate free shampoo can still contain silicones, synthetic fragrance and petrochemical emollients. The term also has no legal definition.
How can I check what is really in a shampoo?
Read the full INCI list rather than the front of the bottle. It is ordered by concentration and standardised across brands, so the same ingredient carries the same name everywhere. Then check whether an independent body certified the product and under which standard.
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