Last updated: June 2026 · The Earthling Co.
Nobody wants to spend 20 minutes in the hair care aisle decoding ingredient labels. But what’s in your shampoo matters more than you might think. The nonprofit Environmental Working Group estimates that, through personal care products, the average person is exposed to dozens of chemicals a day — and some of that exposure can add up over time.
US oversight of cosmetics was historically limited: the core federal law dated to 1938 and went largely unchanged for decades. That shifted in 2022, when the Modernization of Cosmetics Regulation Act (MoCRA) gave the FDA more authority over the industry. Even so, many of the ingredients below remain perfectly legal in shampoo formulas — which is why reading labels still pays off.
This article is general information, not medical advice. Most of these ingredients are legal and considered safe by regulators at the levels used in cosmetics; the concerns noted reflect ongoing research and personal-preference reasons people choose to avoid them.
The 8 Shampoo Ingredients To Avoid: Quick Reference
A Closer Look At Each Ingredient
1. Sulfates
Sulfates are detergents (surfactants) that cut through oil and create the rich foam we associate with “clean.” The trouble is they can be harsh — irritating the skin, eyes, and scalp and stripping natural oils, especially for dry, curly, or color-treated hair. Sulfates can also be contaminated with trace 1,4-dioxane, a byproduct flagged as a probable carcinogen, and they’re often derived from petroleum or palm oil, both environmentally controversial.
On the label: Sodium lauryl sulfate (SLS), sodium laureth sulfate (SLES), ammonium lauryl sulfate, ammonium laureth sulfate
2. Parabens
Parabens are inexpensive preservatives used to stop bacteria, mold, and yeast from growing in water-based products. They’re effective, but some research has associated long-term paraben exposure with hormone disruption and other health concerns. An easy way to sidestep them is to choose waterless products, like shampoo and conditioner bars, which need far fewer preservatives.
On the label: Methylparaben, ethylparaben, propylparaben, butylparaben
3. Phthalates
Phthalates are plasticizers used to make products more flexible and durable; in shampoo they can act as cheap thickeners and help carry scent. They’ve been linked in research to hormonal and developmental concerns. Frustratingly, they’re often hidden inside the catch-all term “fragrance,” which is protected as a trade secret. The Earthling Co.’s natural fragrances contain only essential oils and natural extracts — no hidden plasticizers.
On the label: Diethyl phthalate (DEP), dibutyl phthalate (DBP), “fragrance/parfum”
4. Silicones
Silicones are synthetic polymers that coat the hair for instant, sleek shine. The catch: the effect is temporary and can come with buildup and scalp issues, and silicones may block moisture and nutrients from reaching the hair shaft, leaving strands drier over time. A silicone-free shampoo lets moisture in for a more natural, lasting smoothness.
On the label: Dimethicone, cyclomethicone, amodimethicone, cyclopentasiloxane, phenyl trimethicone
5. Artificial dyes
Many shampoos use synthetic colorants purely to look appealing on the shelf. Some are derived from coal tar (associated with cancer) and can contain heavy-metal traces, and artificial colors can raise the risk of irritation and breakouts for sensitive scalps. Color does nothing for how a shampoo performs, so it’s an easy thing to skip.
On the label: Red 33, Blue 1, Yellow 5, Green 3, or “CI” followed by a number
6. DEA compounds
Diethanolamine (DEA) and related compounds create that creamy, sudsy texture and help balance pH. The International Agency for Research on Cancer has classified some DEA-related ingredients as “possibly carcinogenic,” based largely on animal studies, and researchers have suggested pregnant people may want to limit exposure until more is known.
On the label: Cocamide DEA, diethanolamine, lauramide DEA, TEA (triethanolamine), TEA-lauryl sulfate
7. Formaldehyde and formaldehyde-releasers
Formaldehyde is a preservative with antibacterial properties, but high-level exposure can cause watery eyes, coughing, and skin irritation, and some studies link long-term exposure to increased cancer risk. Many products use “formaldehyde-releasers” that slowly emit small amounts to extend shelf life — worth knowing, since they may not say “formaldehyde” outright.
On the label: Formalin, DMDM hydantoin, quaternium-15, imidazolidinyl urea, methylene glycol
8. Mineral oils
Mineral oil sounds nourishing, but it’s a petroleum byproduct used as a cheap lubricant to reduce tangles. Like silicones, it can build up on the scalp and lead to itchiness, flakes, and dull, lifeless hair, and industrial-level exposure has been linked to increased cancer risk. There are plenty of plant-based oils that condition without the downsides.
On the label: Paraffinum liquidum, liquid petrolatum, white petroleum, paraffin wax
An easier way to skip the questionable stuff
Dissecting every label is exhausting. The shortcut: choose a clean, plant-based shampoo bar that leaves the whole list out from the start. Here’s why ours make it easy:
-
Nourishing, plant-based ingredients that smooth hair and tame frizz without weighing it down.
-
Safe for all hair types — free from sulfates, silicones, mineral oils, and other harsh ingredients, so curly, wavy, and color-treated hair are all welcome.
-
Plastic-free — each bar can divert up to three plastic bottles from landfill.
-
Travel-friendly — waterless and solid, so no TSA hassle or leaks.
-
Budget-friendly — long-lasting and waste-free, and you can use every last bit with a sisal soap saver bag.
Because they’re sulfate-free, bars can lather a little differently than bottled shampoo — wet both your hair and the bar well to build a rich lather. New to bars? See how to use a shampoo bar.
Frequently asked questions
What is the most important ingredient to avoid in shampoo?
If you only change one thing, skip sulfates (SLS/SLES). They’re the most common cause of stripping and scalp irritation, and avoiding them is the single biggest upgrade for dry, curly, or color-treated hair.
How do I know if my shampoo has these ingredients?
Read the ingredient list and scan for the label names above — sulfates end in “sulfate,” silicones often end in “-cone” or “-siloxane,” and “fragrance/parfum” can conceal phthalates. When in doubt, a product that’s explicitly sulfate- and silicone-free removes the guesswork.
Are these ingredients actually dangerous?
Most are legal and considered safe by regulators at the levels used in cosmetics. The concerns come from research into long-term or higher-level exposure, plus irritation and buildup. Avoiding them is a personal, precautionary choice — and an easy one with clean alternatives.
Does “fragrance” really hide other chemicals?
It can. Because fragrance formulas are protected as trade secrets, a single “fragrance” listing may include undisclosed ingredients such as phthalates. Brands that use only essential oils and natural extracts — like The Earthling Co. — don’t hide anything behind that word.
What’s the easiest clean shampoo to switch to?
A plant-based shampoo bar. The Earthling Co.’s shampoo bars and Shampoo & Conditioner set are free of all eight ingredients above and suit every hair type.
Knowledge is power
Next time you shop for shampoo, read the label all the way through — especially the words that are hard to pronounce. Or skip the detective work entirely: a clean, plastic-free routine from The Earthling Co. leaves the questionable ingredients out by design. Start with a Shampoo Bar, pair it with a Conditioner Bar, grab the bestselling Shampoo & Conditioner set, or build a full routine with the Earthling Starter Kit.
Related reading: SLS, SLES, and SCI: What’s the Difference? · Why Are Sulfates Bad for Hair? · The 8 Benefits of Silicone-Free Shampoo & Conditioner.
