Encyclopedia · surfactant
Cocamide MEA and cocamide DEA
Foam boosters and thickeners in shampoo; the DEA type raises nitrosamine and allergy questions, which is why many brands moved to MEA or other thickeners.
What it is
Cocamide DEA (diethanolamide) and cocamide MEA (monoethanolamide) are fatty acid amides of coconut oil used to thicken shampoos and stabilise foam. DEA contains or can release diethanolamine, which can form nitrosamines with nitrosating agents.
How it works
They act as non-ionic co-surfactants that pack into anionic micelles, increasing viscosity and foam.
What the studies show
- A CIR safety assessment of diethanolamides concluded they are safe as used when formulated to be non-irritating and when free DEA is limited. They should not be used in products where N-nitroso compounds can form (Fiume 2013).
- In a patch-test review of 1,767 people tested for cocamide DEA, 18 (1%) were allergic, all with hand dermatitis, and 7 had atopic dermatitis. Shampoos and hand soaps were the main sources, and allergy was rare despite wide use (Mertens 2016).
- A risk assessment of nitrosamines in cosmetics found maximum exposure gave a margin of exposure over 10,000 and a lifetime cancer risk under 1 in 100,000, but the authors say use of amines and nitrosating agents should be minimised (Lim 2018).
This is safety evidence, not evidence of benefit.
Side effects and safety
Contact allergy is rare and concentrated in people with damaged skin (Mertens 2016). The nitrosamine concern is about contaminated or poorly formulated products.
Bottom line
Not a worry for most people. Skip DEA-labelled products if you are allergy-prone or prefer to minimise exposure. It is not essential for cleaning, and there are no hair-specific data.
Studies 3
Fiume MM et al. Safety assessment of diethanolamides as used in cosmetics. 2013
Result: Safe as used when formulated to be non-irritating and free DEA is limited; should not be used where N-nitroso compounds can form.
Read the study ↗Mertens S et al. Allergic contact dermatitis caused by cocamide diethanolamine. 2016
Result: 18 (1%) were allergic, all with hand dermatitis and 7 with atopic dermatitis; shampoos and hand soaps were the main sources; allergy was rare despite wide use.
Read the study ↗Lim DS et al. Risk assessment of N-nitrosodiethylamine (NDEA) and N-nitrosodiethanolamine (NDELA) in cosmetics. 2018
Result: Maximum exposure gave a margin of exposure over 10,000 and a lifetime cancer risk under 1 in 100,000, but the authors say use of amines and nitrosating agents should be minimised.
Read the study ↗Related
- Cocamidopropyl betaineThe most common helper surfactant in shampoo, which makes sulfate cleansers gentler, thicker and foamier, and a rare cause of scalp allergy that usually comes from manufacturing impurities.
- Sodium laureth sulfateThe workhorse cleanser of mainstream shampoos, SLS with a short ethylene-oxide chain added, which keeps most of the cleaning and foam and is gentler, with a trace by-product called 1,4-dioxane.
- Decyl glucosideA plant-derived mild cleanser marketed as ultra-gentle, but its best-documented concern is a rising rate of contact allergy.