High Performance Vitamin C Facial Serum

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).

• fragrance materialBenzyl Alcohol

  • Benzyl Alcohol: Used both as a fragrance component and as a preservative; the EU names it either way. EU Regulation (EC) 1223/2009, Annex III entry 45: 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 (38), which is footnote (37) plus a condition: stock that does not comply may still be made available until 31 July 2028 only "provided that they comply with the restrictions applicable on 15 August 2023", and only if it was lawfully placed on the Union market before the 31 July 2026 cut-off. Entry 45 covers its non-preservative use; it is separately an allowed preservative at Annex V entry 34.

• exfoliating acidSalicylic Acid

  • Salicylic Acid: A beta hydroxy acid that clears the inside of pores; the EU restricts its level and keeps it off children under three. SCCS Opinion on Salicylic Acid, Submission I (SCCS/1601/18, corrigendum of 20 to 21 June 2019); EU Regulation (EC) 1223/2009 Annex III entry 98, as amended by Commission Regulation (EU) 2021/850, which for purposes other than preservation caps it at 3,0% in rinse-off hair products, 2,0% in other products, and 0,5% in body lotion, eye shadow, mascara, eyeliner, lipstick and roll-on deodorant, and states "Not to be used in preparations for children under 3 years of age." Its separate PRESERVATIVE use sits at Annex V entry 3, capped at 0,5% (acid), where the salts carry the carve-out "except for shampoos".

• humectantGlycerin, Sodium Hyaluronate, Sodium PCA, Urea

  • 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."
  • Urea: A humectant the skin already makes; at higher levels it also softens thickened skin. StatPearls, "Moisturizers", NCBI Bookshelf NBK545171, updated 12 February 2024: "Urea is a component of NMF. The addition of urea to moisturizers helps with the absorption of water into the stratum corneum." The FDA label for prescription-strength urea calls it keratolytic and states that its mechanism of action is not yet known.