The Shampoo

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

• comedogenic in testingIsopropyl Myristate

  • Isopropyl Myristate: A light emollient, and the ester the rabbit-ear literature names first. Fulton JE Jr, Pay SR, Fulton JE 3rd, "Comedogenicity of current therapeutic products, cosmetics, and ingredients in the rabbit ear", J Am Acad Dermatol 1984;10(1):96-105, PMID 6229554. The openly readable abstract names this ingredient among its "ingredient offenders", in prose and without a numeric rating: "Ingredient offenders include isopropyl myristate and its analogs, such as isopropyl palmitate, isopropyl isostearate, butyl stearate, isostearyl neopentanoate, myristyl myristate..." The rabbit-ear assay rates raw ingredients and does not predict how a finished formula behaves on human skin.

• common irritantCocamidopropyl Betaine

  • Cocamidopropyl Betaine: A mild cleansing agent, but a recurring patch-test finding, usually traced to leftovers from how it is made. American Contact Dermatitis Society, Allergen of the Year 2004 (Fowler JF Jr, Dermatitis 2004;15(1):3-4).

• fragrance materialLimonene

  • Limonene: A citrus-smelling fragrance component named separately on the label; the one name covers three related isomers. EU Regulation (EC) 1223/2009, Annex III entry 88: a fragrance substance whose presence must be indicated in the list of ingredients above 0,001% in leave-on and 0,01% in rinse-off products, because of established contact-allergy risk. That entry carries transition footnote (37): stock that does not comply, lawfully placed on the Union market before the 31 July 2026 cut-off, may still be made available until 31 July 2028. It is marked on the racemic dl-limonene/Dipentene line and the (S)-(l-limonene) line, but NOT the (R)-p-mentha-1,8-diene (d-limonene) line, CAS 5989-27-5, whose duty was already running as entry 88 before Commission Regulation (EU) 2023/1545 and so needed no transition. All three isomers are declared under the single glossary name "Limonene", so that name on a label does not identify which of them is present.

• humectantGlycerin, Sodium PCA

  • Glycerin: A humectant, and one of the two ingredients a comparison of moisturiser components found made a significant difference to skin hydration. FDA OTC skin protectant monograph, 21 CFR 347.10(h), lists glycerin as a skin protectant at 20 to 45%. On the humectant half: Jeong CB, Han JY, Cho JC, Suh KD, Nam GW, "Analysis of electrical property changes of skin by oil-in-water emulsion components", Int J Cosmet Sci 2013;35(4):402-410, DOI 10.1111/ics.12059, PMID 23621673, found that "glycerine and urea showed significant skin hydration effects compared with other humectants".
  • 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."