Propylene Glycol (E1520)
Propylene glycol is a colourless liquid used in cosmetics as a humectant and solvent, and in food as a carrier and humectant under the code E1520. At the amounts used, it is considered low risk for humans; some people may experience skin irritation or allergy. For pets the picture is different: it is generally tolerated by dogs, but because it can cause anaemia in cats, it is not permitted in cat food in the US, and its use in cat food is also restricted in the EU.
Risk range
1 is the lowest and 10 the highest risk. The range depends on the amount used, whether the product is rinsed off and how it is used. The Temiz İçerik app uses the same ranges.
The lower end applies to low-concentration products; the upper end applies to high-concentration products and to eczema-prone or allergy-prone skin, because of the possibility of irritation and contact allergy.
In food it is mostly present in very small amounts as a carrier in flavouring and colour solutions; the risk is low when intake stays below the acceptable daily intake set by EFSA.
For dog food the range is 3.5–4.5; it is used as a humectant in semi-moist foods and is generally tolerated by dogs. For cats the range is 7.5–8.5: because propylene glycol can cause Heinz body formation in cats' red blood cells and anaemia, it is not permitted in cat food in the US, and its use in cat food is also restricted in the EU.
What is propylene glycol and what does it do?
Propylene glycol (propane-1,2-diol) is a slightly sweet, colourless and odourless liquid. Because of its ability to retain water and dissolve many substances, it is widely used in cosmetics, food, medicines and industry.
In cosmetics it acts as a humectant, a solvent and an auxiliary ingredient that helps deliver active ingredients into the skin. In food it is used as a carrier that dissolves flavourings and colourings, and as a humectant that stops the product drying out.
Which products contain it?
- Moisturisers, serums, deodorants and hair products
- Food flavourings, colouring solutions, some desserts and pastries
- Semi-moist dog foods and treats
- E-cigarette liquids and stage smoke machines
- Some medicinal syrups and creams
On cosmetic labels it is listed as Propylene Glycol, and on food labels as E1520 or propane-1,2-diol. It should not be confused with ethylene glycol, which is toxic and used in antifreeze; the two are different substances.
Is it harmful to humans?
EFSA has re-evaluated propylene glycol and found it safe within the acceptable daily intake. It is quickly broken down and excreted by the body. Very high amounts are reached only in exceptional situations, such as long-term, high-dose use of certain medicines.
In cosmetics, the CIR has found propylene glycol safe at the concentrations used. Its known drawback is that it can cause skin irritation and contact allergy in some people; this is more common on eczema-prone and sensitive skin, and it is one of the substances dermatologists frequently include in patch tests.
Pets: the difference between dogs and cats
In dog food, propylene glycol is used to keep semi-moist foods soft, and at permitted levels it is generally tolerated by dogs.
In cats, however, red blood cells are more sensitive to oxidative damage. Propylene glycol can cause damaged structures called Heinz bodies to form in cats and lead to anaemia. For this reason the FDA in the US does not permit propylene glycol in cat food; EU feed legislation has also restricted its use in cat food. This is another reason not to give dog food or dog treats to cats.
What to do when you see it on a label
- Cosmetics: If your skin does not react, there is nothing to worry about. If you have eczema or a known allergy, you can choose products containing alternative humectants such as glycerin.
- Food: E1520 is usually present in very small amounts; it is no cause for concern in a normal diet.
- Cat owners: Make sure the food and treats you give your cat do not contain propylene glycol; if your cat seems lethargic or pale, see a vet.
Frequently asked questions
Is propylene glycol antifreeze?
No. The toxic antifreeze substance is ethylene glycol. Propylene glycol is a different substance and is permitted in food and cosmetics.
Is propylene glycol safe for dogs?
It is used in dog food at permitted levels and is generally tolerated. If you notice a problem in your dog, consult your vet.
Can cat food contain propylene glycol?
It is not permitted in cat food in the US, and its use is also restricted in the EU, because it can cause anaemia in cats.
Can propylene glycol cause skin allergy?
In some people, especially those with eczema, it can cause irritation or contact allergy. If in doubt, a patch test can be done by a dermatologist.
Sources
Updated: 2026-10-11 · How we score
This page is for general information and is not personal medical advice. Warnings on the product label and the advice of a health professional always come first.