Label Literacy 101: 5 Ingredients to Avoid in Your Pet's Shampoo

Bath time just ended. Your dog smells like "spring meadow" (whatever that means), and the shampoo bottle sitting on the counter claims it's "gentle" and "perfect for pets."

But what if (cue dramatic music!) that bottle is lying???

If you’ve walked down any pet aisle, you’d have come across countless shampoo options. Organic this, hypoallergenic that. The labels promise miracles. But the ingredients? Eh.

At The Good Paws, we're all about cutting through the marketing fluff and weeding out the clutter on what actually belongs on your pup's skin.

For the uninitiated, your dogs' skin pH sits closer to neutral or alkaline (around 6.2–7.4) compared to humans' more acidic 5.5, which means harsh or sensitizing ingredients can disrupt their skin barrier way more easily.

So, before the next bath, let's talk about the harmful ingredients in pet shampoo that deserve a hard pass, shall we?

1. "Fragrance" or "Parfum" (Often Hiding Phthalates)

Sounds innocent enough, right? Who doesn't want their dog smelling like lavender fields or ocean breezes?

But "fragrance" or "parfum" is an umbrella term that can hide dozens—sometimes hundreds—of undisclosed chemicals. Manufacturers aren't required to list what's actually in that "fragrance blend," which means phthalates (hormone disruptors linked to endocrine issues) often sneak in as fixatives.

The American Kennel Club explicitly recommends avoiding artificial fragrances in dog shampoos to reduce the risk of irritation. Phthalates have been associated with kidney and liver problems, reproductive system issues, and allergic reactions in both humans and dogs.

On labels, look for: Fragrance, parfum, aroma, perfume oils. Phthalates are rarely declared (e.g., DEP, DBP).

Pick instead: Fragrance-free formulas with full INCI (International Nomenclature of Cosmetic Ingredients) disclosure.

Tip: "Unscented" doesn't mean fragrance-free; it can still contain masking fragrances.

2. Formaldehyde-Releasing Preservatives

Nobody wants embalming fluid anywhere near their dog, yet formaldehyde-releasing preservatives show up in pet shampoos all the time.

These preservatives, like DMDM hydantoin, quaternium-15, imidazolidinyl urea, and diazolidinyl urea, release trace amounts of formaldehyde over time. Formaldehyde and its releasers are well-documented contact allergens and frequent culprits in allergic contact dermatitis. Symptoms can include burning, itching, blistering, and skin scaling.

While manufacturers reformulated "slow-releasing" compounds to reduce immediate exposure, it's still formaldehyde, and the jury's still out on long-term cancer links.

On labels, look for: DMDM hydantoin, quaternium-7/15/31/61, imidazolidinyl urea, diazolidinyl urea, bromopol, sodium hydroxymethylglycinate.

Pick instead: Products that declare "formaldehyde-releaser-free" or use alternative preservative systems.

3. Isothiazolinones (MI/MCI)

Methylisothiazolinone (MI) and methylchloroisothiazolinone (MCI) are potent preservatives that pack a punch… and not in a good way.

Recent scientific reviews reaffirm MI as a major inducer of allergic contact dermatitis in consumer products, with significant allergic reactions documented even at low concentrations. There's also strong evidence that methylisothiazolinone acts as a neurotoxin.

Given how sensitive dogs' skin can be, exposing them to known irritants and potential neurotoxins makes zero sense.

On labels, look for: Methylisothiazolinone, methylchloroisothiazolinone, Kathon CG.

Pick instead: MI/MCI-free formulas with alternative, lower-sensitization preservative systems.

4. Harsh Sulfates (SLS/SLES)

Sulfates are the reason shampoos foam like a cloud factory. Sodium lauryl sulfate (SLS) and sodium laureth sulfate (SLES) are incredibly effective cleansers, which is exactly the problem.

They're comparatively more irritating and lipid-stripping, especially on dogs' more alkaline skin. Frequent baths with sulfate-heavy shampoos can dry out coats, cause redness and itching, and even lead to skin infections. Sulfates have also been linked to cataracts in dogs, making them especially risky around the eyes.

In its powder form, SLS is a known skin irritant and may cause organ system toxicity if inhaled.

On labels, look for: Sodium lauryl sulfate (SLS), sodium laureth sulfate (SLES), ammonium lauryl sulfate, ammonium laureth sulfate.

Pick instead: Milder surfactants like decyl glucoside, coco-glucoside, or cocamidopropyl betaine in pH-balanced-for-dogs formulas.

Tip: The Good Paws' sulphate-free shampoos skip the harsh detergents and stick to gentle, skin-loving alternatives that won't strip your dog's natural oils.

5. Parabens (Methyl-, Propyl-, Butylparaben)

Parabens have been standard preservatives in cosmetics for decades, but that doesn't mean they're safe.

While many regulators allow parabens at low levels, consumer and veterinary guidance—including the AKC—flags them as avoidable due to concerns about irritation and ongoing debates over endocrine disruption. Studies since 2004 have suggested relationships between parabens and breast cancer in humans; choosing paraben-free products reduces cumulative exposure for both pets and handlers.

In pets, parabens are known to cause skin irritation, rashes, and skin infections, with allergic reactions linked to hormonal changes.

On labels, look for: Methylparaben, propylparaben, butylparaben, ethylparaben.

Pick instead: Paraben-free systems with clear preservative disclosure.

Bonus Red Flags

Beyond the big five toxic dog shampoo ingredients, watch for these extras when reading labels:

Artificial dyes (FD&C/CI colors): Purely cosmetic with zero benefit; synthesized from petroleum and linked to organ damage, cancer, birth defects, and allergic reactions.

Proprietary blends: Vague terms like "proprietary blend of coat conditioners" or "perfume oils" are red flags. Transparency = trust.

Cocamide DEA/MEA: Despite the coconut-sounding name, it's chemically altered and classified as a moderate cancer-causing ingredient, hormone and thyroid disruptor, and organ toxin.

Propylene glycol: Linked to liver and kidney poisoning, skin irritation, and organ system disorders in humans; best avoided for pets, too.

How to Read Dog Shampoo Labels Like a Pro

Dog shampoo label reading doesn't require a chemistry degree, merely a few smart habits:

1. Check the first five ingredients: They're the highest concentration. If sulfates or parabens are near the top, keep looking.
2. Look for full INCI disclosure: Ingredient lists should be transparent. Avoid vague catch-alls or missing information.
3. Scan for pH-balanced claims: Dog-specific formulas should call this out. Human shampoo won't.
4. Choose fragrance-free over "unscented": "Unscented" can still contain masking fragrances; fragrance-free means none at all.
5. Prefer gentle surfactants: Glucosides and betaines are milder than SLS/SLES.
6. Avoid anything "proprietary": If they won't tell you what's in it, don't put it on your dog.

The Label-Reading Glow-Up

The pet industry isn't as tightly regulated as the human cosmetics industry, which means manufacturers can get away with a lot. The responsibility, therefore, falls on us: the humans who actually read the fine print.

Once you know what ingredients to avoid in dog shampoo, label-reading becomes second nature. You'll start spotting the red flags instantly, and bath time transforms from "cross your fingers and hope this doesn't irritate their skin" to "I know exactly what I'm using and why".

At The Good Paws, we want to make safe, science-backed grooming accessible. Our sulphate-free, toxin-free formulas skip the nasties and stick to pH-balanced, gentle ingredients that actually belong on your dog's skin.

When it comes to your pup's health, reading labels is part of preventive care.

From label detectives to bath-time pros, it's all good.

Got questions about a specific shampoo ingredient or want to share your label-reading wins? Drop it in the comments or DM us @thegoodpawsclub. We're in this together, one squeaky-clean paw at a time! 

About the author: Amritesh Mukherjee is a writer, journalist, editor and companion to the handsomest doggo of the universe, Dusky.