Skin Research C-Esta Serum

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

• fragrance materialFarnesol, Linalool, Amyl Cinnamal, Benzyl Salicylate, Cinnamal, Limonene, Eugenol, Hydroxycitronellal, Butylphenyl Methylpropional

  • Farnesol: A soft floral fragrance component named separately on the label. EU Regulation (EC) 1223/2009, Annex III entry 82: 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.
  • Linalool: A floral fragrance component named separately on the label. EU Regulation (EC) 1223/2009, Annex III entry 84: 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.
  • Amyl Cinnamal: A jasmine-like fragrance component named separately on the label. EU Regulation (EC) 1223/2009, Annex III entry 67: 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.
  • Benzyl Salicylate: A faintly floral fragrance component named separately on the label. EU Regulation (EC) 1223/2009, Annex III entry 75: 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. The entry was replaced by Commission Regulation (EU) 2026/909 of 27 April 2026, which caps it per product type from 0,004% in oral products to 4% in fragrance products; under its footnote (**), products not complying may not be placed on the Union market from 1 January 2027, nor made available from 1 July 2028.
  • Cinnamal: A cinnamon-scented fragrance component named separately on the label. EU Regulation (EC) 1223/2009, Annex III entry 76: 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.
  • 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.
  • Eugenol: A clove-scented fragrance component named separately on the label. EU Regulation (EC) 1223/2009, Annex III entry 71: 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.
  • Hydroxycitronellal: A lily-like fragrance component named separately on the label. EU Regulation (EC) 1223/2009, Annex III entry 72: 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.
  • 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.

• undeclared fragrance blendFragrance

  • Fragrance: A blend the label does not itemize, so what is in it cannot be read from the ingredient list. EU Regulation (EC) 1223/2009 permits the collective term "parfum"; the SCCS Opinion on Fragrance Allergens (SCCS/1459/11) reviews the contact-allergy evidence for the substances it can contain.

• 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%.

• humectantUrea, Panthenol, Sodium Hyaluronate

  • 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.
  • Panthenol: A provitamin B5 humectant used in products aimed at irritated and healing skin. On the humectant half: Ferreira VTP, Silva GC, Martin AA, Maia Campos PMBG, "Topical dexpanthenol effects on physiological parameters of the stratum corneum by Confocal Raman Microspectroscopy", Skin Res Technol 2023;29(9):e13317, DOI 10.1111/srt.13317, PMID 37753694, PMCID PMC10504581, open access, Introduction: "As a humectant, it has been shown to retain water more efficiently than other humectants during the last stages of dehydration..." On the soothing half, which that paper does NOT support: Cho YS, Kim HO, Woo SM, Lee DH, "Use of Dexpanthenol for Atopic Dermatitis—Benefits and Recommendations Based on Current Evidence", J Clin Med 2022;11(14):3943, DOI 10.3390/jcm11143943, PMID 35887707, open access, section 3.5: "To facilitate wound healing, dexpanthenol reduces inflammation, and promotes cell proliferation and epithelial remodeling."
  • 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.

• soothingPanthenol

  • Panthenol: A provitamin B5 humectant used in products aimed at irritated and healing skin. On the humectant half: Ferreira VTP, Silva GC, Martin AA, Maia Campos PMBG, "Topical dexpanthenol effects on physiological parameters of the stratum corneum by Confocal Raman Microspectroscopy", Skin Res Technol 2023;29(9):e13317, DOI 10.1111/srt.13317, PMID 37753694, PMCID PMC10504581, open access, Introduction: "As a humectant, it has been shown to retain water more efficiently than other humectants during the last stages of dehydration..." On the soothing half, which that paper does NOT support: Cho YS, Kim HO, Woo SM, Lee DH, "Use of Dexpanthenol for Atopic Dermatitis—Benefits and Recommendations Based on Current Evidence", J Clin Med 2022;11(14):3943, DOI 10.3390/jcm11143943, PMID 35887707, open access, section 3.5: "To facilitate wound healing, dexpanthenol reduces inflammation, and promotes cell proliferation and epithelial remodeling."