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Glycerol (E 422), a polyol humectant

Glycerin (glycerol)

Glycerin is a safe, well-studied moisturising ingredient: creams with 15% to 20% glycerol improved dry skin and skin barrier function in randomised trials, including a 251-child trial in eczema-related dryness, though glycerol alone did not always beat its own cream base. As a food additive (E 422) it is judged safe at normal uses, but slush ice drinks made with it have caused glycerol intoxication in young children, and the UK Food Standards Agency says children under 7 should not have them. We found no trials of glycerin for hair.

Updated
30 September 2026
Clear glycerin in a small glass bottle beside a spoon
At a glance
Last reviewed 30 September 2026
Evidence
Moderate
Best for
Dry skin (xerosis)
Typical form & use
Cream or lotion, about 20% glycerol
Onset
About a week
Safety
Not in slush drinks for under-7s (glycerol intoxication). No interactions in our data.
Check with your medications →

What it's used for

Evidence is rated per use. The same ingredient can be strong for one thing and traditional for another.

UseEvidenceWhat the research shows
Dry skin and atopic dermatitis dryness, in creamsModerateIn 24 adults with atopic dermatitis, a 20% glycerol cream applied twice daily for 4 weeks improved skin hydration significantly versus a glycerol-free placebo and restored barrier function by the authors' measure (a later review calls the water-loss change numerical), but did not change erythema or SCORAD severity. In 251 children aged 2 to 6, a cream of glycerol plus paraffin beat its vehicle over 28 days (66.1% responders versus 45.6%), and stopping it brought relapse. The picture for glycerol alone is mixed: a review of basic emollients reports that in one trial of 74 patients, 20% glycerol cream did not differ from its glycerol-free base on water loss or capacitance, while a 4% urea cream did better on dryness, and in a 197-patient trial glycerin was equal to urea for dryness with less smarting. Many of these products combine glycerol with paraffin or petrolatum, so the benefit cannot be credited to glycerol alone.1,3,2,5
Skin barrier repair after damageLimitedIn two studies in healthy volunteers, glycerol applied after tape stripping or repeated washing with detergent sped up recovery of barrier function (transepidermal water loss) and raised hydration, and the faster repair was still present 7 days after treatment ended. These were short studies on artificially damaged skin, and the authors argue the effect is more than simple water-holding. We did not find trials of everyday barrier repair in larger groups.4
Hair conditioning, in productsTraditionalThe Cosmetic Ingredient Review panel lists glycerin as a hair conditioning agent, humectant and skin conditioner, and concluded it is safe in cosmetics at the concentrations and practices it reviewed. We found no clinical trial of glycerin for hair growth, dryness or frizz, so this is use in products, not proven benefit.6
Slush ice drinks (a harm, not a benefit)LimitedA review of 21 children in the UK and Ireland (2009 to 2024, median age 3 years 6 months) found that, almost all within 60 minutes of a glycerol slush drink, they had reduced consciousness, low blood sugar and acidosis. None had a relevant history, no inherited metabolic disease was found in the 14 tested, and 95% avoided slush drinks afterwards without recurrence. This is a case series, not a trial; it is the basis for the FSA's advice.10,9

How much

Ranges below are what studies used and what supplements commonly contain. They are not a recommendation for you. Start at the low end.

Studied topical strength
About 20% glycerol in a cream1,2
The strength used in the atopic dermatitis trials, applied twice daily for 4 weeks or daily for 30 days. One child trial used glycerol with paraffin but the abstract does not state the strength.
Food additive (EU)
No ADI needed; no safety concern at reported uses7
EFSA's 2017 re-evaluation found glycerol (E 422) of low acute toxicity and set no numerical acceptable daily intake. It noted that oral therapeutic doses of 1,000 to 1,500 mg per kg given as a bolus can cause headache, nausea and vomiting.
Single-drink limit (EFSA, 2026)
125 mg per kg body weight per drink8
EFSA's acute reference dose for one drinking event. It found slush drinks at reported use levels would exceed it for all population groups, and recommended maximum levels for glycerol in beverages.
UK advice on slush drinks
None under 7; under 10s one 350 ml a day9
FSA advice for slush ice drinks, pouches and home kits containing glycerol. Check with the seller whether a drink contains glycerol.
Timing · The creams were applied once or twice daily. The barrier-repair studies applied glycerol after the skin was damaged.With food? · Not applicable to skin use. As a drink ingredient, the risk is a large amount in one sitting, so the UK limit is per drink and per day.How long to trial · Trials of creams ran 4 weeks, and a review notes that improvement faded when emollient use stopped, so moisturising is something you keep doing. Fluhr's barrier studies saw an effect at 3 to 7 days.

How people take it

Moisturiser with glycerol (often with paraffin or petrolatum)15–20% glycerol in trialsGlycerol holds water; paraffin or petrolatum slows evaporation, and a review of emollient studies notes additive benefits from combining humectant and occlusive ingredients.
Hair and skin care product ingredientNot standardisedListed as glycerin on labels. CIR found it safe as used; no clinical trials for hair.
Food additive E 422 (humectant, sweetener substitute)Small amounts in foodsUsed to keep foods moist. In slush drinks it replaces sugar and keeps the drink from freezing solid, at levels that matter for young children.
Oral glycerol (medical use)1,000–1,500 mg per kg as a bolusA therapeutic osmotic dose given in glaucoma, not a supplement. It raised plasma osmolality and caused headache, nausea and vomiting in some patients (EFSA).

Safety

Who should avoid
  • Children under 7 — no slush drinks containing glycerol (FSA)
  • Children under 10 — no more than one 350 ml glycerol slush drink a day
  • Large single oral doses — headache, nausea, vomiting, raised blood osmolality
  • Glycerol slush kits and pouches — check the label; the advice applies to them too
Known interactions
No interactions in our data. Absence of a flag is not clearance.

Questions people ask

What are the benefits of glycerin for skin?

It draws water into the outer skin and creams with 15% to 20% glycerol improved dryness and barrier function in randomised trials, including in children with eczema-related dryness. It works best in a cream that also has an oil or paraffin, and in one trial glycerol alone did not differ from its glycerol-free base. Expect the effect to fade if you stop.

Is glycerin good for hair?

It is a common conditioning and moisturising ingredient in hair products, and the Cosmetic Ingredient Review panel found it safe as used. We found no clinical trials showing it helps hair growth, dryness or frizz.

Is glycerin (E 422) safe to eat?

At normal food uses, yes: EFSA found no safety concern and no need for a numerical daily limit in 2017. The exception is drinks that contain a lot of it in one go. In 2026 EFSA found that slush drinks would exceed its single-drink reference dose for all groups, and recommended limits for glycerol in beverages.

Why shouldn't young children have slush drinks with glycerol?

Glycerol replaces sugar in some slush drinks, and a large dose in a small child can cause headache, sickness, low blood sugar, shock and loss of consciousness. The FSA says children under 7 should not have them, and under-10s should have at most one 350 ml drink a day. If a child feels unwell after one, the FSA says to give a sugary drink or food and call 111; call 999 if they become drowsy or confused.

Sources

  1. Randomised controlled trial Breternitz M, Kowatzki D, Langenauer M, Elsner P, Fluhr JW. Placebo-controlled, double-blind, randomized, prospective study of a glycerol-based emollient on eczematous skin in atopic dermatitis: biophysical and clinical evaluation. Skin Pharmacol Physiol. 2008.
  2. Randomised controlled trial Lodén M, Andersson AC, Anderson C, et al. A double-blind study comparing the effect of glycerin and urea on dry, eczematous skin in atopic patients. Acta Derm Venereol. 2002.
  3. Randomised controlled trial Boralevi F, Saint Aroman M, Delarue A, et al. Long-term emollient therapy improves xerosis in children with atopic dermatitis. J Eur Acad Dermatol Venereol. 2014.
  4. Clinical study Fluhr JW, Gloor M, Lehmann L, Lazzerini S, Distante F, Berardesca E. Glycerol accelerates recovery of barrier function in vivo. Acta Derm Venereol. 1999.
  5. Review Wollenberg A, Barbarot S, Torrelo A. Basic emollients for xerosis cutis in atopic dermatitis: a review of clinical studies. Int J Dermatol. 2025.
  6. Safety assessment Becker LC, Bergfeld WF, Belsito DV, et al. Safety assessment of glycerin as used in cosmetics. Int J Toxicol. 2019.
  7. Regulator opinion EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS). Re-evaluation of glycerol (E 422) as a food additive. EFSA J. 2017.
  8. Regulator opinion EFSA Panel on Food Additives and Flavourings (FAF). Safety of acute exposure to the food additive glycerol (E 422) from beverages. EFSA J. 2026.
  9. Regulator guidance Food Standards Agency. Glycerol: slush ice drinks containing glycerol (guidance published 16 July 2025). GOV.UK.
  10. Case series Brothwell SL, Fitzsimons PE, Gerrard A, et al. Glycerol intoxication syndrome in young children, following the consumption of slush ice drinks. Arch Dis Child. 2025.

Reader notes

Experiences and questions from readers, read by an editor before they appear. They are personal accounts, not evidence, and are not medical advice.

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Last reviewed 30 September 2026 · Next review March 2027 · How we rate evidence