Barefaced Overachiever

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

• common irritantPropylene Glycol

  • 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).

• humectantGlycerin, Sodium Hyaluronate, 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 Hyaluronate: A humectant that holds a large amount of water at the skin surface. Chylińska N, Maciejczyk M, "Hyaluronic Acid and Skin: Its Role in Aging and Wound-Healing Processes", Gels 2025;11(4):281, DOI 10.3390/gels11040281, PMID 40277717, open access: hyaluronic acid's "high osmotic activity and anionic structure enable it to bind large amounts of water", and "sodium and potassium hyaluronate are widely used in moisturizing products". The same review notes that high-molecular-weight hyaluronic acid does not penetrate the deeper layers.
  • 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."

• soothingBisabolol, Allantoin

  • Bisabolol: The main soothing component isolated from chamomile. Eddin LB et al., "Health Benefits, Pharmacological Effects, Molecular Mechanisms, and Therapeutic Potential of alpha-Bisabolol", Nutrients 2022;14(7):1370, DOI 10.3390/nu14071370, PMID 35405982, open access: it "is integrated in many cosmetic formulations due to its skin soothing effects, well documented dermal absorption and the absence of dermal irritations or photosensitivity following its application". The EMA HMPC assessment report on Matricaria recutita (EMA/HMPC/55837/2011) discusses its anti-inflammatory data.
  • Allantoin: A skin protectant used at low levels in products aimed at irritated skin. FDA OTC skin protectant monograph, 21 CFR 347.10(a), lists allantoin as a skin-protectant active at 0,5 to 2%. Its labelled indications are 21 CFR 347.50(b)(1), "temporarily protects minor: cuts, scrapes, burns", and (b)(2), which covers chafed, chapped or cracked skin. The monograph does not give it the "minor skin irritation and itching" wording; that one belongs to colloidal oatmeal, sodium bicarbonate and one combination, and to topical starch without the itching half.