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PEGs (polyethylene glycols) are a huge family of emulsifiers, thickeners and solubilisers that hold modern creams and cleansers together. They sit on the flagged list for one main reason: PEGs are made by ethoxylation, a process that can leave trace amounts of 1,4-dioxane — a probable carcinogen — in the finished ingredient. The PEGs themselves have a long use history; the debate is about purification, contamination limits, and their ability to increase how much of other ingredients penetrates skin.
What PEG compounds are and what they do in a product
"PEG" followed by a number (the average number of ethylene oxide units) names a family ranging from liquids to waxy solids. In formulas they are the diplomats: they help oil and water mix, dissolve fragrances and actives into water-based products, thicken cleansers, and give creams their stable texture. Related ethoxylated ingredients — the "-eth" family such as laureths and ceteareths, and ingredients like polysorbates — share the manufacturing story even when the label does not begin with PEG.
You have almost certainly used PEGs today: they are in toothpaste, shampoo, moisturiser, liquid foundation and most shower gels, typically in the middle of the ingredient list doing unglamorous structural work.
Where you will find PEG compounds
- Creams and lotions (emulsifiers such as PEG-100 stearate)
- Cleansers, shampoos and shower gels (PEG-40 hydrogenated castor oil solubilises fragrance and oils)
- Toothpastes, mouthwashes and many liquid medicines and cosmetics bases
- Any ingredient ending in "-eth" (laureth-4, ceteareth-20) or named as a polysorbate — all ethoxylated
Why people avoid PEG compounds
The 1,4-dioxane question comes first. Ethoxylation can generate 1,4-dioxane as a by-product; it is classified as a probable human carcinogen and is an environmental contaminant of concern. Finished ingredients can be vacuum-stripped to reduce it to very low levels, and good manufacturers do — but consumers cannot see purification certificates on a label, so some choose to avoid the category. The second concern is penetration: PEGs can increase skin permeability, which matters most on damaged or eczematous skin, where ingredients that would otherwise stay on the surface may pass more easily. Third is a values concern — PEGs are petroleum-derived and only slowly biodegradable.
For balance: the same contamination topic applies to SLES, the ethoxylated cleanser in most shampoos (see sulfates), so PEG-avoiders usually end up reading for the whole ethoxylated family.
What regulators and the evidence say
The US FDA has monitored 1,4-dioxane in cosmetics for decades, reports that levels have declined as purification improved, and continues periodic testing; it has not banned PEGs. New York State went further than education: its law sets maximum 1,4-dioxane limits for cosmetics and cleaning products (phasing down to 1 ppm for cosmetics), effectively forcing purification standards on the whole US market. The EU permits PEGs in cosmetics with purity expectations under its general safety regime.
Safety reviews of PEGs themselves (by the Cosmetic Ingredient Review) find them safe as used when formulated appropriately, while noting the damaged-skin caveat — a sensible summary of the whole file: the ingredient is fine for intact skin in normal use; the contaminant is the part to keep shrinking.
How to spot PEG compounds on a label
- PEG- followed by a number (PEG-6, PEG-40, PEG-100, PEG-150...)
- Ingredients ending in -eth (laureth, ceteareth, steareth, oleth) — ethoxylated relatives
- Polysorbate 20/60/80 and polyethylene glycol spelled out
- "PEG-free" claims now appear on natural-leaning brands and simplify the search
What is used instead
Non-ethoxylated emulsifiers are plentiful: polyglyceryl esters (polyglyceryl-3 methylglucose distearate and family), glucoside emulsifiers (cetearyl glucoside, arachidyl glucoside), lecithin, and classic glyceryl stearate systems without PEG partners. Formulas built on them feel marginally different — sometimes richer, sometimes less elegant — which is why mainstream products still lean on PEGs. Shoppers motivated by the contamination issue specifically can also simply favour brands that publish 1,4-dioxane testing; several large manufacturers now do.
PEGs are a good example of this guide's philosophy: the flag is about a process and a principle, which you can only act on if you know the label names. The rest of the flagged list is full of similar cases.
Reading a real label: PEGs at work
Try the exercise on a cream you own. The emulsifier system usually sits in the first third of the list: something like "PEG-100 Stearate" paired with glyceryl stearate is the classic skeleton of a mid-century-style cream that still dominates pharmacy shelves, while "Polysorbate 20" lower down is typically solubilising the fragrance. A "PEG-free" reformulation of the same product will show polyglyceryl or glucoside names in those slots instead — cetearyl glucoside, polyglyceryl-3 methylglucose distearate. Once you can see the slots, you can see the whole category: PEGs are rarely the point of a product, they are its plumbing, and the choice to avoid them is a choice about manufacturing standards rather than about any single jar's behaviour on your skin this morning.
Frequently asked questions
Are PEGs themselves carcinogenic?
No — the concern is not PEG but 1,4-dioxane, a probable carcinogen that can contaminate PEGs during manufacture. Purification can reduce it to very low levels, and regulators monitor it; New York State now caps it in cosmetics sold there.
What is 1,4-dioxane and why is it in cosmetics?
It is a by-product of ethoxylation, the process used to make PEGs and several other ingredients (including SLES) gentler and more soluble. It is never an ingredient on purpose; it arrives as a trace contaminant unless removed.
Should people with eczema avoid PEGs?
PEGs can increase skin penetration, which matters more on broken or inflamed skin, and some dermatologists suggest caution with leave-on products on damaged skin for that reason. For intact skin, safety reviews find PEGs acceptable as used.
How can I tell if a brand controls 1,4-dioxane?
Look for published testing or compliance statements — since New York's limits took effect, many national brands state that products meet the standard. A brand that will not say anything is not necessarily unsafe, but the transparent ones make the choice easy.
Are PEGs bad for the environment?
PEGs are petroleum-derived and degrade slowly; they pass through wastewater treatment in part. The environmental case is real but modest compared with their contaminant headline — most avoiders cite 1,4-dioxane first.
Are PEGs vegan / petroleum-free?
PEGs are synthetic and petroleum-derived, though no animal ingredients are involved in the standard process, so most vegan certifications accept them while 'petroleum-free' and some natural standards do not. If both properties matter to you, PEG-free natural brands are the overlap you are looking for.
Checked against US FDA, EWG Skin Deep cosmetics database, New York State DEC, ITRC (Interstate Technology & Regulatory Council) sources · Last updated 2026-10-22 · How we assess ingredients
Sources (5)
- US FDA — Cosmetics information
- EWG Skin Deep cosmetics database
- New York State DEC — 1,4-dioxane limits for household, personal care and cosmetic products
- ITRC (Interstate Technology & Regulatory Council) — 1,4-dioxane: history of use and potential sources
- EWG — Hundreds of kids' cosmetics products may contain hidden carcinogen (1,4-dioxane from ethoxylation)
