Evidence recordApplied to skin
Glycerin
Answer
Human studies of complete creams found that 20% glycerin increased measured skin hydration; effects on other endpoints depended on the formulation.
Check the formulaEvidence grade
Strong
Several consistent, relevant sources or an authoritative synthesis support this bounded claim.
Where it stops
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.
Sources
Sources · 3
Source 1
Int J Cosmet Sci, 2001- Design
- Bilateral randomized double-blind study
- Participants
- 17
- Duration
- 10 days
- Reported numbers
- 20%
- Measured outcome
- skin hydration, transepidermal water loss, sodium lauryl sulphate irritation response
- Studied formulation
- 20% glycerin cream, vehicle cream
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.
Source 2
Acta Derm Venereol, 2002- Design
- Randomized double-blind study
- Participants
- 197
- Duration
- 30 days
- Reported numbers
- 10%, 24%
- Measured outcome
- dryness, smarting
- Studied formulation
- 20% glycerin cream, cream base without glycerin, 4% urea plus 4% sodium chloride cream
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.
Source 3
J Cosmet Dermatol, 2020- Design
- Randomized double-blind four-arm crossover study
- Participants
- 51
- Duration
- 12 hours
- Measured outcome
- transepidermal water loss, corneometry
- Studied formulation
- glycerol plus petrolatum emollient, vehicle, vehicle plus glycerol, vehicle plus petrolatum
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.