Hydrate Leave-In Conditioner

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, Imidazolidinyl Urea, Melaleuca Alternifolia Leaf Oil

  • 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).
  • Imidazolidinyl Urea: A preservative the FDA lists as a formaldehyde releaser, so formaldehyde-reactive skin can notice it. How much reaches the skin depends on the whole formula, not on this name alone. EU Regulation (EC) 1223/2009, Annex V entry 27, permits imidazolidinyl urea as a preservative up to 0,6%. The FDA names it among the "formaldehyde and formaldehyde releasing ingredients" on its Allergens in Cosmetics page (content current 25 February 2022). Annex V preamble point 2, as amended by Commission Regulation (EU) 2022/1181, requires the warning "releases formaldehyde" on any product whose total released formaldehyde exceeds 0,001% (10 ppm). That Regulation states the sensitisation ground itself, so the chain is drawn by the regulator and not by us: recital (2) names the class, "Certain of those preservatives are gradually releasing formaldehyde in order to fulfil a preserving function in the final cosmetic product (so called formaldehyde releasers)", and recital (3) gives the purpose of the warning, "In order to inform consumers sensitised to formaldehyde about the presence of formaldehyde that may trigger an allergic reaction". Recital (1) records that formaldehyde is classified a skin sensitizer (Category 1) in Part 3 of Annex VI to Regulation (EC) 1272/2008.
  • Melaleuca Alternifolia Leaf Oil: An essential oil whose oxidation products carry its sensitising potential; the EU assesses it as a moderate skin sensitiser. SCCS Scientific Opinion on Tea Tree Oil (CAS/EC 68647-73-4 / 285-377-1), SCCS/1681/25, adopted 30 October 2025, which concludes it is a moderate skin sensitiser. It does not set maximum levels of its own: it assesses the concentrations the applicant defended, and finds no concern at 2,0% in shampoo, 1,0% in shower gel, 1,0% in face wash and 0,1% in face cream, for oil conforming to ISO 4730:2017, in adults, in non-sprayable formats. It draws on the earlier SCCP opinions SCCP/1155/08 and SCCP/0843/04 and incorporates their data by reference; it says nothing about their status.

• retinoidRetinyl Palmitate

  • Retinyl Palmitate: A gentler vitamin A ester that the skin converts to retinol. SCCS Opinion on Vitamin A (Retinol, Retinyl Acetate, Retinyl Palmitate), SCCS/1576/16, which assesses retinyl palmitate by name; EU Regulation (EC) 1223/2009 Annex III entry 376 covers it in the same group as retinol.

• 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".