{
  "id": "glycerin",
  "idVersion": 1,
  "ingredient": "Glycerin",
  "route": "topical",
  "grade": "strong",
  "gradeLabel": "Strong",
  "claim": "Human studies of complete creams found that 20% glycerin increased measured skin hydration; effects on other endpoints depended on the formulation.",
  "caveat": "These studies tested complete creams, not glycerin in isolation. One short vehicle-controlled study found no added improvement in transepidermal water loss or surfactant response, and a separate comparator trial found equal improvement in dryness rather than superiority.",
  "published": "2026-09-19",
  "sources": [
    {
      "url": "https://pubmed.ncbi.nlm.nih.gov/18498456/",
      "journal": "Int J Cosmet Sci",
      "year": 2001,
      "n": 17,
      "design": "Bilateral randomized double-blind study",
      "duration": "10 days",
      "percentages": [
        "20%"
      ],
      "outcome": "skin hydration, transepidermal water loss, sodium lauryl sulphate irritation response",
      "finding": "Bilateral randomized double-blind study in 17 healthy volunteers over 10 days: the 20% glycerin cream increased measured skin hydration versus vehicle, but did not improve transepidermal water loss or the response to sodium lauryl sulphate.",
      "formulation": "20% glycerin cream, vehicle cream"
    },
    {
      "url": "https://pubmed.ncbi.nlm.nih.gov/12013198/",
      "journal": "Acta Derm Venereol",
      "year": 2002,
      "n": 197,
      "design": "Randomized double-blind study",
      "duration": "30 days",
      "percentages": [
        "10%",
        "24%"
      ],
      "outcome": "dryness, smarting",
      "finding": "Randomized double-blind study in 197 people with atopic dermatitis over 30 days: dryness improved equally with the glycerin and urea/saline creams; moderate or severe smarting was reported by 10% with glycerin versus 24% with urea/saline.",
      "formulation": "20% glycerin cream, cream base without glycerin, 4% urea plus 4% sodium chloride cream"
    },
    {
      "url": "https://pubmed.ncbi.nlm.nih.gov/31532576/",
      "journal": "J Cosmet Dermatol",
      "year": 2020,
      "n": 51,
      "design": "Randomized double-blind four-arm crossover study",
      "duration": "12 hours",
      "percentages": [],
      "outcome": "transepidermal water loss, corneometry",
      "finding": "Randomized double-blind four-arm crossover study in 51 people measured over 12 hours: the complete emollient outperformed vehicle; the glycerol component contributed to hydration while petrolatum contributed to the transepidermal-water-loss effect.",
      "formulation": "glycerol plus petrolatum emollient, vehicle, vehicle plus glycerol, vehicle plus petrolatum"
    }
  ],
  "peopleReport": null
}