CPSR for Shampoo and Conditioner: What the Safety Assessor Actually Checks

Shampoo and conditioner look like the simplest products a brand can launch, yet they raise more assessor questions than most people expect. A shampoo is a concentrated surfactant system that is worked into a lather and rinsed past the eyes, often every day for years. A conditioner is a cationic emulsion that sits on hair and skin for a few minutes before it is rinsed away. Both are water-based, so both need preserving, and both are fragranced, so both declare allergens.

In the EU the legal framework is Regulation (EC) No 1223/2009. Great Britain uses the retained version of the same regulation, enforced through the Cosmetic Products Enforcement Regulations 2013. The exposure methods come from the SCCS Notes of Guidance. If you are new to safety reports, start with what a CPSR is. This guide covers liquid shampoo and conditioner; solid formats have their own guide to CPSRs for shampoo and conditioner bars.

How rinse-off exposure changes the arithmetic

The first thing an assessor does with a shampoo is apply the right exposure model, and it is very different from a leave-on product. The SCCS Notes of Guidance assume about 10.46 g of shampoo a day. Almost all of it is rinsed away, so the calculation applies a retention factor of 0.01: only about 1% of the product is treated as staying on the skin. As a result, daily exposure to each ingredient is a small fraction of what the same concentration would deliver in a body lotion. Systemic margins of safety in a shampoo are usually comfortable, even for ingredients that would be a concern in a leave-on product.

Rinse-off conditioner uses the same 0.01 retention factor, but the SCCS assumes a smaller daily amount of about 3.92 g. The difference between the two products is mostly local: conditioner stays in contact for longer, and its cationic ingredients are skin and eye irritants at higher levels.

Leave-in conditioners and leave-in masks are not rinse-off products at all. They are assessed as leave-on with a retention factor of 1, which surprises brands that treat everything used in the shower as one category. Dry shampoo is a third case: it is a leave-on product applied as an aerosol or powder, so inhalation becomes part of the assessment. Our guide to leave-on versus rinse-off CPSRs explains the difference in more detail.

The surfactant system, and what each part does

The combination matters more than any single ingredient. An anionic surfactant used alone is markedly more irritating than the same surfactant blended with an amphoteric, which is why almost every commercial shampoo pairs the two. The assessor looks at the total active matter, the ratio between the surfactant classes, and whether the formula includes the mildness ingredients a well-built cleanser contains.

Eye irritation: the defining question for shampoo

Shampoo reaches the eyes routinely, not occasionally, and for children it does so at almost every wash. Animal testing for cosmetics is banned, so the assessor builds the eye irritation case from several sources:

• published data on each surfactant
• the total active matter of the finished formula
• read-across from closely comparable products
• the pH
• in vitro data, where the brand has commissioned it, from reconstructed human cornea models or the bovine corneal opacity and permeability (BCOP) assay

For most conventional formulas within established active-matter ranges, the ingredient-level evidence is enough. Commissioned testing becomes necessary for a novel surfactant blend, a very high active matter, or a claim such as "no tears" or "suitable for children". Our guide to which lab tests cosmetics need covers what each test delivers.

Preservation in a wet environment

A shampoo bottle lives in a shower, which is warm, humid and splashed with water, and the bottle is opened often. The preservative system therefore has to control the microbes present at manufacture and also those introduced over months of use. Every water-based shampoo and conditioner needs a preservative from Annex V at an effective level, and every one needs a challenge test on the actual formula.

Two failures come up again and again:

• pH. Organic acid preservatives such as sodium benzoate and potassium sorbate only work well in acidic conditions, roughly pH 5.5 and below. A glucoside-based sulfate-free shampoo often sits at pH 8 or higher until it is corrected, and at that pH those preservatives are largely ineffective.
• The surfactant itself. Micelles can trap some preservatives and reduce the free concentration available to work. That is why a system that passed in a simple formula can fail in a richer one.

Our guide to cosmetic preservatives explains the options.

pH: why shampoo and conditioner differ

The two products are formulated to different pH ranges.

• Shampoo typically sits between pH 5 and 6.5. That is close enough to skin pH to be comfortable on the scalp while still letting the surfactants work.
• Conditioner usually sits lower, between pH 3.5 and 5. Mild acidity helps the cuticle lie flat, which gives the smoothness people expect from conditioning, and cationic conditioning agents perform better in acidic conditions.

The assessor records both values measured with a calibrated meter and checks each against the preservative's working range. A pH range is often set as a release specification. Sulfate-free shampoos built on glucosides need particular care, because the raw materials are alkaline. See our guide to pH in cosmetics.

Cationic conditioning agents and their Annex III limits

Conditioners work through quaternary ammonium compounds. These positively charged molecules bind to the negatively charged surface of damaged hair and stay there through rinsing. The three alkyltrimethylammonium chlorides above have fixed Annex III limits when used for conditioning rather than as preservatives. Those limits were introduced by Regulation (EU) No 866/2014. Other common quats, such as behentrimonium methosulfate, are not listed in Annex III, so the assessor evaluates them on their own toxicological data.

The most common correction in a conditioner file is a leave-in product formulated at the rinse-off level, for example 2% cetrimonium chloride where the leave-on hair limit is 1%. Cationics also irritate the eyes and skin at higher concentrations, so the assessor weighs level and exposure together and does not treat the annex maximum as automatically acceptable. See our guide to restricted ingredients in Annex III.

Silicones and sulfates: the facts separated from the marketing

Silicones and sulfates are both lawful and widely used, and neither creates a compliance problem just by being present.

• Silicones. Dimethicone and its relatives are large, inert molecules that coat the hair, reduce friction and add shine. They are among the most studied cosmetic ingredients. The exception is the cyclic siloxanes. Under EU REACH Annex XVII entry 70, D4 and D5 have been restricted to below 0.1% in wash-off cosmetics since 31 January 2020. Regulation (EU) 2024/1328 extends the 0.1% limit to D6 and to all other cosmetics from 6 June 2027. This is an environmental rule rather than a safety finding, and GB has its own UK REACH regime.
• Sulfates. These are effective cleansers. They are irritating on their own and much less so when properly blended. A sulfate-free formula is a legitimate positioning choice, not automatically a safety improvement.

Both become a compliance matter through claims. "Silicone free" and "sulfate free" are free-from claims. In the UK and EU, a free-from claim that implies a lawful ingredient is unsafe fails the fairness criterion. The compliant version says what the formula does contain and what that delivers. See claims that are not allowed.

Fragrance allergens in hair care

Shampoo and conditioner are among the most heavily fragranced products in a bathroom. Both must declare fragrance allergens present above the rinse-off threshold of 0.01% in the finished product. That threshold is ten times higher than the leave-on threshold of 0.001%, so fewer allergens cross it at the same fragrance level. Hair care is often fragranced heavily enough that several still do, and leave-in products use the leave-on threshold.

In the EU, Regulation (EU) 2023/1545 expands the list of individually labelled allergens from the original 26 to more than 80. New products placed on the EU market must comply from 31 July 2026, and products already on the market have until 31 July 2028. For GB, check the current OPSS position separately. Our guides to the expanded allergen list and labelling fragrance allergens set out the details.

What you can claim

For the evidence each claim type needs, see which hair care claims are testable and claim substantiation explained.

A worked example: a two-product launch

A brand submits a sulfate-free shampoo and a matching conditioner.

The shampoo uses coco-glucoside, decyl glucoside and cocamidopropyl betaine at a normal combined active matter. It is preserved with a sorbate and benzoate blend and fragranced at 0.8%. The measured pH comes back at 7.9 because the glucosides were not corrected, which puts the preservative outside its working range. The brand adjusts the pH to 5.2 with citric acid and buffers it, and the challenge test then passes. Eye irritation is assessed from the ingredient data and judged acceptable for an adult product. The draft claim "gentle enough for children" is removed because no testing supports it.

The conditioner uses behentrimonium chloride at 2%, within the 5% rinse-off limit. It sits at pH 4.3 and passes its challenge test first time.

Both products: fragrance allergens are calculated against the expanded EU list, giving three declarable allergens for the shampoo and two for the conditioner. The draft claim "repairs damage" is removed from both for lack of a test, and the brand books a combing-force study for the following season. The products are assessed together as a multiple-variant submission. The launch slips by four weeks, entirely because of the pH correction and the repeat challenge test.

The submission checklist

• The full formula for each product, with percentages to two decimal places.
• Safety data sheets and specifications for every raw material, including the active matter of each surfactant solution.
• The fragrance IFRA certificate and an allergen statement with percentages against the expanded list.
• The measured pH of each product, taken with a calibrated meter.
• The challenge test report for each formula.
• Stability data, which supports the period after opening.
• The packaging specification, including the closure.
• Draft label artwork and every claim you intend to make.
• How the product is used: rinsed off immediately, left on, or left in.

Hair care rewards getting the basics right: the pH, the preservative, the allergen calculation and honest claims. Get those four right and a shampoo file is one of the most straightforward a brand will ever commission. A consultation before formulation catches the glucoside pH problem, which delays more hair care launches than anything else. If you are budgeting, see how much a CPSR costs and pricing for multiple variants.

Related reading

• What is a CPSR?
• CPSR for solid shampoo and conditioner bars
• CPSR for hair oil
• Hair dyes: labelling and CPSR requirements
• Hair loss products: cosmetic or medicinal?
• All regulatory compliance articles

Myths we hear

• Rinse-off products do not need preservatives. Every water-based product does, and a shower is the worst storage environment in the house.
• Sulfate free means gentle. The replacement surfactants decide that, and glucoside systems bring their own pH problem.
• Silicones are banned. They are lawful in hair care. Only the cyclic D4, D5 and D6 carry EU REACH limits.
• A conditioner is just a thin cream. Its cationics carry Annex III limits that differ between rinse-off and leave-on use.
• A natural shampoo cannot sting the eyes. Glucosides and botanical surfactants are perfectly capable of stinging.

What to do this week

1. Measure the pH of every hair product with a calibrated meter.
2. Check it against your preservative's working range.
3. Check every cationic against its Annex III entry for the right use type.
4. Request allergen statements with percentages against the expanded list.
5. Remove any repair or growth claim you cannot evidence.

Frequently asked questions

Official sources and legislation

• Regulation (EC) No 1223/2009 on cosmetic products
• Regulation (EU) No 866/2014 (Annex III limits for cetrimonium, steartrimonium and behentrimonium chloride)
• Regulation (EU) 2023/1545 (fragrance allergen labelling)
• Regulation (EU) 2024/1328 (REACH restriction on D4, D5 and D6)
• Cosmetic Products Enforcement Regulations 2013
• Scientific Committee on Consumer Safety (SCCS) and Notes of Guidance
• OPSS guidance: Regulation 1223/2009 and the CPER 2013 (Great Britain)