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Worth knowing · Shampoo preservative

Cosmetic preservatives

Also appears on labels as: dmdm hydantoin, methylisothiazolinone, benzisothiazolinone, caprylhydroxamic acid, glyceryl caprylate, methylisothiazolinone/methylchloroisothiazolinone

Antimicrobials that keep a water-based product from growing bacteria and mold in the bottle, and the boosters sold beside them, such as caprylyl glycol and ethylhexylglycerin.

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 27 scored products

We flag it by name on 26 of them. Lowest scores first.

Panel Score 79 out of 100, grade B: Good, check the flags
BiokleenBac-Out Pet Stain & Odor Remover, Foaming Spray

flagged on this product's score page

Panel Score 79 out of 100, grade B: Good, check the flags
PuracyNatural Pet Stain & Odor Remover

flagged on this product's score page

Panel Score 79 out of 100, grade B: Good, check the flags
Kids 'N' PetsMom's Miracle Stain + Odor Remover

flagged on this product's score page

Panel Score 80 out of 100, grade B: Good, check the flags
OxyfreshPremium Pet Toothpaste

flagged on this product's score page

Panel Score 84 out of 100, grade B: Good, check the flags
Arm & HammerSuper Deodorizing Shampoo, Kiwi Blossom

flagged on this product's score page

Panel Score 84 out of 100, grade B: Good, check the flags
Arm & HammerClump & Seal Multi-Cat Clay Litter

flagged on this product's score page

Panel Score 84 out of 100, grade B: Good, check the flags
Arm & HammerCloud Control Platinum Cat Litter

flagged on this product's score page

Panel Score 84 out of 100, grade B: Good, check the flags
Arm & HammerSlide Multi-Cat Cat Litter

flagged on this product's score page

Panel Score 86 out of 100, grade B: Good, check the flags
Bio-GroomProtein Lanolin Dog Shampoo

flagged on this product's score page

Panel Score 86 out of 100, grade B: Good, check the flags
PetLab CoDental Formula for Dogs & Cats

flagged on this product's score page

Panel Score 86 out of 100, grade B: Good, check the flags
PRIDE+GROOMThe Sensitive One Shampoo

flagged on this product's score page

Panel Score 86 out of 100, grade B: Good, check the flags
EarthbathOatmeal & Aloe Conditioner, Vanilla & Almond

flagged on this product's score page

Panel Score 87 out of 100, grade B: Good, check the flags
Earth RatedUnscented Dog Grooming Wipes

flagged on this product's score page

Panel Score 87 out of 100, grade B: Good, check the flags
Skout's HonorProbiotic Paw Spray for Dogs & Cats

flagged on this product's score page

Panel Score 87 out of 100, grade B: Good, check the flags
Skout's HonorProbiotic Ear Cleaner for Dogs & Cats

flagged on this product's score page

Panel Score 88 out of 100, grade B: Good, check the flags
kin+kindOrganics Jasmine + Lily Oatmeal Shampoo

flagged on this product's score page

Panel Score 88 out of 100, grade B: Good, check the flags
Chris ChristensenSmart Rinse Hypoallergenic All Coat Conditioner

flagged on this product's score page

Panel Score 90 out of 100, grade A: Pretty good
PRIDE+GROOMThe Non Shedder Shampoo

flagged on this product's score page

Panel Score 90 out of 100, grade A: Pretty good
PRIDE+GROOMThe Shedder Shampoo

flagged on this product's score page

Panel Score 90 out of 100, grade A: Pretty good
EarthbathHypoallergenic Cat Wipes

flagged on this product's score page

Panel Score 90 out of 100, grade A: Pretty good
EarthbathHypoallergenic Dog Wipes

flagged on this product's score page

Panel Score 90 out of 100, grade A: Pretty good
EarthbathHypoallergenic Cat Shampoo

flagged on this product's score page

Panel Score 90 out of 100, grade A: Pretty good
EarthbathHypoallergenic Cat Grooming Foam

flagged on this product's score page

Panel Score 92 out of 100, grade A: Pretty good
Chris ChristensenSpectrum Ten Shampoo

flagged on this product's score page

3 more scored products list this ingredient. Showing the 24 lowest-scoring.