the nood serum

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

• exfoliating acidLactic Acid

  • Lactic Acid: An alpha hydroxy acid that loosens surface skin cells; it also makes skin more sun-sensitive while you use it. FDA, "Guidance for Industry: Labeling for Topically Applied Cosmetic Products Containing Alpha Hydroxy Acids as Ingredients" (announced at 70 FR 1721, 10 January 2005; FDA web pages title it "Labeling for Cosmetics Containing Alpha Hydroxy Acids"), which names this acid and recommends the statement "Sunburn Alert: This product contains an alpha hydroxy acid (AHA) that may increase your skin's sensitivity to the sun and particularly the possibility of sunburn."

• rich occlusiveDimethicone

  • Dimethicone: A silicone that forms a film on the surface of the skin without an oily feel. FDA OTC skin protectant monograph, 21 CFR 347.10(g), lists dimethicone as a skin protectant at 1 to 30%.

• humectantGlycerin

  • 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".

• barrier lipidCeramide NP, Cholesterol

  • Ceramide NP: One of the lipid families the skin barrier is actually built from. Feingold KR and Elias PM, "The role of ceramides in the disruption of the cutaneous permeability barrier, a common manifestation of skin disorders", J Lipid Res 2024;65(8):100593, DOI 10.1016/j.jlr.2024.100593, open access: the barrier lipid matrix "by weight is approximately 50% ceramides, 25% cholesterol, and 15% free fatty acids".
  • Cholesterol: One of the three lipid classes that make up the skin barrier, alongside ceramides and fatty acids. Feingold KR and Elias PM, J Lipid Res 2024, open access: the barrier lipid matrix "by weight is approximately 50% ceramides, 25% cholesterol, and 15% free fatty acids". Corroborated by Wertz PW, "Roles of Lipids in the Permeability Barriers of Skin and Oral Mucosa", Int J Mol Sci 2021;22(10):5229, DOI 10.3390/ijms22105229, PMID 34063352.

• soothingAvena Sativa Kernel Flour, Bisabolol

  • Avena Sativa Kernel Flour: One of the ingredients the FDA recognises by name as an over-the-counter skin protectant for irritation and itching. FDA OTC skin protectant monograph, 21 CFR 347.10(f): "Colloidal oatmeal, 0.007 percent minimum; 0.003 percent minimum in combination with mineral oil in accordance with 347.20(a)(4)."; section 347.50(b)(4) gives it the indication "temporarily protects and helps relieve minor skin irritation and itching due to:" followed by at least one of rashes, eczema, poison ivy/oak/sumac, or insect bites. The indication is conditional on naming a cause; the same opening phrase also serves sodium bicarbonate at (b)(5), so the phrase alone does not identify oatmeal.
  • 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.