Ingredient library

Worth knowing · Shampoo preservative

Cosmetic preservatives

Also appears on labels as: dmdm hydantoin, methylisothiazolinone, benzisothiazolinone, caprylhydroxamic acid, glyceryl caprylate, disodium edta

Antimicrobials that keep a water-based product from growing bacteria and mold in the bottle. EDTA is a chelator that boosts them and softens hard water.

Watched ingredients get highlighted on every product panel you open.

Where it comes from
Chemical synthesis.
Why it's in the product
Shelf stability. A shampoo without a preservative system is a mold culture waiting to happen, so the alternative is not zero preservative.
Safety and toxicity
Two of these deserve naming. DMDM hydantoin is a formaldehyde releaser, and while the released amount is small, formaldehyde is a known human carcinogen and contact sensitizer. Methylisothiazolinone and its relatives are potent contact allergens and have been restricted in leave-on cosmetics in the EU for that reason.
Interactions and who should be careful
If your pet develops itching or redness that starts after bath time rather than being helped by it, the preservative system is a reasonable suspect. Gentler alternatives such as caprylhydroxamic acid and glyceryl caprylate do exist and appear on better-formulated panels.

General reference, not veterinary advice. Dose, breed, and existing conditions change the answer, so talk to your vet before changing what your pet eats. Think we got this wrong? Tell us and we log it publicly.

Found in 6 scored products

Lowest scores first. Its presence here is not what drove those scores.