Ingredient review

Undecylenamide DEA

INCI: Undecylenamide DEA

Undecylenamide DEA is a synthetic foaming agent that helps cleansers lather and thicken, but it can be drying or irritating for sensitive skin.

beautyskincaresurfactant

In plain English

Undecylenamide DEA is a man-made ingredient added to cleansers and shampoos to create a rich, stable foam and to make the product feel thicker. It works by helping oil and water mix so dirt and oil can be rinsed away. While effective, it can strip the skin's natural moisture barrier, leading to dryness or irritation, especially for those with sensitive or eczema-prone skin.

Review score

Safety, usefulness, and evidence

3.5Good
3.5/ 5

Potentially useful with some tradeoffs

The evidence base is useful, but some claims depend heavily on the formula.

Main practical flags: irritation is moderate; clogging risk is low.

Source
synthetic
Evidence
moderate
Irritation
moderate
Clogging risk
low
How reviews are scored

Quick decision guide

Useful, but context matters

Undecylenamide DEA can be useful, but watch for some irritation potential.

Plain-English read

Treat this as a practical screening step before you compare products that contain this ingredient.

  1. Step 1Start with the score, then check the irritation and clogging risk before judging Undecylenamide DEA.
  2. Step 2Use the "Best for" and "Use caution if" sections to match the ingredient to your skin, not just to a marketing claim.
  3. Step 3If a product stings, breaks you out, or worsens irritation, judge the finished formula and stop using it even if the ingredient scores well.

Score terms in plain English

Irritation risk

moderate

Can bother some users, especially with frequent use, damaged skin, or strong companion ingredients.

Clogging risk

low

Less likely to feel heavy or contribute to clogged pores for most skin types.

Evidence level

moderate

There is useful support, but formula details and claim strength still matter.

What it is

Undecylenamide DEA is a diethanolamide derivative of undecylenic acid, a fatty acid found naturally in castor oil. It is synthesized for use as a surfactant and foam booster in personal care products.

How it works

As a surfactant, it reduces the surface tension between water and oil, allowing the product to lift dirt, sebum, and makeup from the skin. It also stabilizes foam and increases the viscosity (thickness) of liquid cleansers.

Pros

Excellent foaming

Produces a dense, stable lather that many people associate with a satisfying cleansing experience.

Improves product feel

Thickens the formula, giving a luxurious, creamy texture that spreads easily on skin or hair.

Cons and cautions

Potential for irritation

Can strip the skin's natural oils, leading to tightness, dryness, or redness, especially with frequent use.

Nitrosamine concern

If combined with nitrosating agents (e.g., certain preservatives), it may form nitrosamines, which are potential carcinogens. Reputable brands avoid this combination.

Best for

  • People with normal to oily skin who enjoy a foamy cleanser
  • Those looking for an effective oil-removing shampoo

Use caution if

  • Individuals with sensitive, dry, or eczema-prone skin
  • Anyone with a known allergy to amide-based surfactants

Usage tips

Use a moisturizer after cleansing to replenish the skin barrier.
If you have sensitive skin, choose a cleanser with a milder surfactant blend instead.
Rinse thoroughly to avoid any residue that could cause irritation.

Safety summary

Undecylenamide DEA is generally safe for most people when used in rinse-off products at low concentrations. However, it can be drying and irritating for sensitive skin, and there is a theoretical risk of nitrosamine contamination if formulated improperly. The cosmetic industry has moved toward milder alternatives in recent years.

Research notes

Studies indicate that DEA-based surfactants can cause skin irritation at high concentrations. The CIR panel concluded that undecylenamide DEA is safe as used in rinse-off products, provided it is not combined with nitrosating agents. No recent large-scale human studies are available.

Common label clues

Typical concentration
0.5% to 5%
Regulatory status
Approved for use in cosmetics in the US (FDA) and EU (CosIng) at concentrations typically up to 5%. The Cosmetic Ingredient Review (CIR) panel has noted that DEA-based ingredients should not be used with nitrosating agents to avoid nitrosamine formation.
Common uses
Cleansers, Shampoos, Body washes, Facial washes
Environmental note
Undecylenamide DEA is not readily biodegradable and may accumulate in aquatic environments. Its production involves synthetic chemistry, not renewable plant sources.

Good to know

  • Undecylenamide DEA is not the same as cocamide DEA, though they are chemically similar.
  • It is often used in combination with other surfactants to reduce irritation.
  • The 'DEA' stands for diethanolamine, a compound that has raised safety concerns in high concentrations.

Common questions

What is Undecylenamide DEA in beauty products?

Undecylenamide DEA is a man-made ingredient added to cleansers and shampoos to create a rich, stable foam and to make the product feel thicker. It works by helping oil and water mix so dirt and oil can be rinsed away. While effective, it can strip the skin's natural moisture barrier, leading to dryness or irritation, especially for those with sensitive or eczema-prone skin.

What does Undecylenamide DEA do in a beauty product?

As a surfactant, it reduces the surface tension between water and oil, allowing the product to lift dirt, sebum, and makeup from the skin. It also stabilizes foam and increases the viscosity (thickness) of liquid cleansers.

Is Undecylenamide DEA safe for most people?

Undecylenamide DEA is generally safe for most people when used in rinse-off products at low concentrations. However, it can be drying and irritating for sensitive skin, and there is a theoretical risk of nitrosamine contamination if formulated improperly. The cosmetic industry has moved toward milder alternatives in recent years.

Who should be careful with Undecylenamide DEA?

Individuals with sensitive, dry, or eczema-prone skin Anyone with a known allergy to amide-based surfactants

Research sources

Cosmetic Ingredient Review (CIR) – Safety Assessment of DEA IngredientsOpenFDA – Cosmetics IngredientsOpenPubChem – Undecylenamide DEAOpen

Ingredient reviews are educational and are not medical advice. Patch test new products and ask a licensed clinician about persistent irritation, allergies, pregnancy-specific questions, or diagnosed skin conditions.