Dimethylaminopropylamine (DMAPA)
The hidden impurity behind most "cocamidopropyl betaine" allergy — the reason a gentle shampoo can flare your scalp
INCIDimethylaminopropylamine
- Category
- Surfactant
- Risk level
- medium
- It's an impurity, not an added ingredient
- DMAPA is a residual from making cocamidopropyl betaine (CAPB) — and the actual sensitiser in most cases blamed on "CAPB allergy"
- Batch-to-batch variation
- Better-purified CAPB has less residual DMAPA — so the same product name can be more or less allergenic depending on manufacturing
- Not on the label
- DMAPA isn't listed; you look for Cocamidopropyl Betaine (CAPB) as the ingredient that may carry it
Look for these names on ingredient lists
This ingredient may appear under any of these names:
Commonly found in
Possible reactions
- Scalp dermatitis / flaking mistaken for dandruff
- Facial, neck and eyelid dermatitis from shampoo rinse water
- Hand dermatitis from liquid soap
- Occupational hand dermatitis in hairdressers
Top picks without Dimethylaminopropylamine (DMAPA)
Highly rated products whose ingredient lists don't include Dimethylaminopropylamine (DMAPA).
As an Amazon Associate, AllerNote earns from qualifying purchases.
Always scan the actual label before use — formulations change.
Scan a product for this concern
What is DMAPA?
Dimethylaminopropylamine (INCI: Dimethylaminopropylamine; DMAPA; 3-dimethylaminopropylamine) is a diamine used to manufacture cocamidopropyl betaine (CAPB) — one of the most common mild surfactants in shampoos, body washes and liquid soaps, especially "sulfate-free" ones. DMAPA isn't an intended ingredient: it's a residual impurity left in CAPB when purification is incomplete.
The discovery that DMAPA — not CAPB itself — is the primary sensitiser in most "CAPB allergy" was an important one. It explains why different CAPB-containing products cause reactions of differing severity: manufacturing quality (how thoroughly DMAPA is removed) determines how allergenic a given product really is. DMAPA is routinely tested alongside CAPB in shampoo-allergy work-ups.
Why it causes reactions
DMAPA is a bifunctional amine — its two reactive amine groups readily bind skin proteins to form haptens, driving Type IV delayed hypersensitivity. As a diamine it's more reactive than a simple monoamine, which is why it sensitises even at the low levels present as an impurity. Typical presentations:
- Scalp dermatitis — redness, scaling and itch, often misread as dandruff or seborrhoeic dermatitis.
- Facial / eyelid dermatitis — from rinse water flowing over the face during washing.
- Hairdresser's hand dermatitis — chronic occupational shampoo exposure.
- Hand dermatitis — from CAPB-containing liquid hand washes.
DMAPA is one of my favourite "the label doesn''t tell the whole story" cases. People diligently avoid sulfates, switch to a gentle CAPB shampoo, and still flare — because the real trigger is an impurity that never appears on any ingredient list. The actionable trick is to scan for "Cocamidopropyl Betaine" itself, since that''s the ingredient that may be carrying the DMAPA. — Snehal
Where it's found
DMAPA isn't added on purpose — it rides along as an impurity in:
- Cocamidopropyl betaine (CAPB) — in most mild, "sulfate-free" shampoos and washes.
- Related amidopropyl betaine surfactants made by similar routes.
Since it's not on labels, look for Cocamidopropyl Betaine / CAPB (and note coco-betaine is a related-but-different compound often grouped with it).
Safer alternatives
- Different surfactant systems — sodium cocoyl isethionate (SCI), sodium lauroyl sarcosinate, disodium cocoyl glutamate (no DMAPA).
- CAPB-free sensitive-skin shampoos — e.g. Vanicream, Free & Clear.
- Solid shampoo bars using soap- or sarcosinate-based systems.
- Check baby shampoos for CAPB absence.
The bottom line
DMAPA is the residual impurity in cocamidopropyl betaine that's the real allergen behind most "CAPB allergy" — the reason a gentle, sulfate-free shampoo can still flare your scalp, face or hands, and why reactions seem inconsistent between brands. It's not on labels, so scan for "Cocamidopropyl Betaine", switch to a different surfactant family, and patch test both CAPB and DMAPA to confirm.
Was this article helpful?
One tap tells us what to write more of. No account needed.
Is this ingredient in your products?
Scan any cosmetic product to check for Dimethylaminopropylamine (DMAPA) and 30+ other allergens instantly.