Keratina Shampoo

These describe what an ingredient is, not whether it is a problem. The stance marks above are the ratings; these are not.

• commonly dryingAlcohol

  • Alcohol: A fast-evaporating solvent that leaves a dry finish. International Chemical Safety Card ICSC 0044, Ethanol (anhydrous), prepared by an international group of experts for the ILO and WHO: "The substance defats the skin, which may cause dryness or cracking." Bommannan et al., as reported by Lachenmeier DW, "Safety evaluation of topical applications of ethanol on the skin and inside the oral cavity", J Occup Med Toxicol 2008;3:26, DOI 10.1186/1745-6673-3-26, open access, reference 82: "Bommannan et al. found in vivo in humans that ethanol enters the skin and removes measurable quantities of the lipid barrier material from the stratum corneum." Both describe stronger exposures than a cosmetic formula.

• common irritantDMDM Hydantoin, Propylene glycol, Methylchloroisothiazolinone, Methylisothiazolinone

  • DMDM Hydantoin: A preservative the FDA lists as a formaldehyde releaser, which is why formaldehyde-reactive skin can notice it. How much reaches the skin depends on the whole formula, not on this name alone. EU Regulation (EC) 1223/2009, Annex V entry 33, permits DMDM hydantoin as a preservative up to 0,6%. The FDA names it among the "formaldehyde and formaldehyde releasing ingredients" on its Allergens in Cosmetics page (content current 25 February 2022). SCCS Scientific Advice SCCS/1632/21, on the threshold for the "contains formaldehyde" warning, describes a study in which a moisturiser spiked to the 0,6% Annex V maximum released at least 40 ppm formaldehyde. Annex V preamble point 2, as amended by Commission Regulation (EU) 2022/1181, requires the warning "releases formaldehyde" on any product whose total released formaldehyde exceeds 0,001% (10 ppm). That Regulation states the sensitisation ground itself, so the chain is drawn by the regulator and not by us: recital (2) names the class, "Certain of those preservatives are gradually releasing formaldehyde in order to fulfil a preserving function in the final cosmetic product (so called formaldehyde releasers)", and recital (3) gives the purpose of the warning, "In order to inform consumers sensitised to formaldehyde about the presence of formaldehyde that may trigger an allergic reaction". Recital (1) records that formaldehyde is classified a skin sensitizer (Category 1) in Part 3 of Annex VI to Regulation (EC) 1272/2008.
  • Propylene glycol: A solvent that shows up in patch-test clinics, more often as irritation than as allergy. American Contact Dermatitis Society, Allergen of the Year 2018 (Jacob SE, Scheman A, McGowan MA, Dermatitis 2018;29(1):3-5).
  • Methylchloroisothiazolinone: A preservative restricted to rinse-off products in the EU because of contact-allergy reports. EU Regulation (EC) 1223/2009, Annex V entry 39 (rinse-off only, 0,0015% of a 3:1 mixture with methylisothiazolinone). The reason is in Commission Regulation (EU) No 1003/2014, recital 3, quoted rather than summarised: "The SCCS concluded that the mixture of Methylchloroisothiazolinone (and) Methylisothiazolinone in a ratio of 3:1 does not pose a risk to the health of the consumer when used as a preservative up to a maximum authorised concentration of 0,0015 % in rinse-off cosmetic products, apart from its skin sensitising potential. The SCCS indicated that induction and elicitation would be less likely in a rinse-off product than when the same concentration is present in a leave-on product." SCCS/1238/09 concludes it "is well recognised as an important skin sensitiser at current conditions of use".
  • Methylisothiazolinone: A preservative that patch-test clinics see reactions to often enough that the EU banned it from leave-on products. American Contact Dermatitis Society, Allergen of the Year 2013 (Castanedo-Tardana MP, Zug KA, Dermatitis 2013;24(1):2-6); SCCS Opinion on Methylisothiazolinone (P94), Submission II, SENSITISATION ONLY (SCCS/1521/13, revision of 27 March 2014); banned in leave-on cosmetics by Commission Regulation (EU) 2016/1198, which recites the need to address "the increased incidence of allergies induced by methylisothiazolinone".

• fragrance materialButylphenyl Methylpropional

  • Butylphenyl Methylpropional: A lily-of-the-valley fragrance component the EU no longer permits in cosmetics. It was a declarable fragrance allergen at Annex III entry 83 of EU Regulation (EC) 1223/2009. Commission Regulation (EU) 2021/1902 deleted that entry and moved it to Annex II entry 1666 (2-(4-tert-butylbenzyl) propionaldehyde, CAS 80-54-6), prohibiting it in cosmetic products from 1 March 2022.

• retinoidRetinyl Palmitate

  • Retinyl Palmitate: A gentler vitamin A ester that the skin converts to retinol. SCCS Opinion on Vitamin A (Retinol, Retinyl Acetate, Retinyl Palmitate), SCCS/1576/16, which assesses retinyl palmitate by name; EU Regulation (EC) 1223/2009 Annex III entry 376 covers it in the same group as retinol.

• humectantSodium PCA

  • Sodium PCA: The salt of PCA, one of the water-holding substances the outer layer of skin makes for itself. Dörner C, Steinbinder J, Sachslehner AP, Sukseree S, Eckhart L, "Amino Acid Metabolism of the Skin: Control by Specific Enzymes and Contribution to Protective Functions", Metabolites 2025;15(9):601, DOI 10.3390/metabo15090601, open access, section "Glutamine Is Converted to Pyrrolidone Carboxylic Acid, a Component of the NMF": "pyrrolidone carboxylic acid (PCA), also known as pyroglutamic acid or 5-oxoproline, accumulates in the stratum corneum."