Is Your Shampoo the Reason Behind Your Thinning Hair?

Is Your Shampoo the Reason Behind Your Thinning Hair?

Even to this day, and with all the knowledge freely available about the risks of certain shampoo ingredients, many products on the shelves still contain potentially harmful chemicals. While shampoo is an essential part of maintaining hair hygiene, the irony is that some formulas may actually undermine the health of your scalp and hair. From causing irritation to disrupting your hormones, many shampoo ingredients have been linked to hair thinning, breakage, and even long-term hair loss. In this guide, we’ll dive deep into the ingredients most commonly associated with these issues, explaining what they are, how they work, and why they may be causing your hair to shed more than it should.

Sodium Lauryl Sulfate (SLS) & Sodium Laureth Sulfate (SLES)

Sodium Lauryl Sulfate (SLS) and its derivative Sodium Laureth Sulfate (SLES) are harsh detergents commonly used to create that luxurious foamy lather in shampoos. While effective at removing oil and dirt, these sulfates strip the scalp of its natural protective oils, leaving it vulnerable to dryness, irritation, and inflammation. With repeated use, they can weaken hair follicles and increase hair shedding. Sulfates are a prime suspect when hair feels brittle or falls out in clumps during washing.

Parabens (Methylparaben, Propylparaben, etc.)

While some are banned and others restricted in the EU, Parabens are widely used by other countries as preservatives in shampoos to prevent bacterial growth and extend shelf life.  These chemicals are known to mimic estrogen in the body, potentially disrupting the hormonal balance critical to hair growth. Studies suggest a link between parabens and endocrine disruption, which could result in changes to the hair growth cycle, leading to increased shedding or thinning. Long-term exposure, especially when combined with other hormone-disrupting ingredients, may elevate this risk.

Formaldehyde & Formaldehyde-Releasing Preservatives

Often disguised as DMDM hydantoin, quaternium-15, or imidazolidinyl urea, formaldehyde-releasing preservatives are used in shampoos to kill bacteria and extend product life. Formaldehyde is banned in the EU and classified as a Category 1B carcinogen and a skin sensitizer. It can cause a cascade of skin issues, including allergic reactions, rashes, and inflammation. For the scalp, these reactions can damage the hair follicles, disrupt the natural growth environment, and lead to thinning or hair loss over time. This ingredient has come under increasing scrutiny, with some products pulled from shelves due to consumer complaints of significant hair fall.

Phthalates (Often Hidden in “Fragrance” or “Parfum”, Benzyl Butyl Phthalate, Diethyl Phthalate, Bis(2-ethylhexyl) phthalate (DEHP), Di-n-propyl phthalate)

Phthalates are used in hair care to bind and stabilize synthetic fragrances. Unfortunately, they’re not listed by name and often fall under the vague term “fragrance” or “parfum” - a category that can legally include over 4,000 undisclosed chemicals, some which are listed as carcinogens. Phthalates are suspected endocrine disruptors, and like parabens, may interfere with hormone regulation. Though research into direct links between phthalates and hair loss is ongoing, the indirect effects - hormone disruption and inflammation - make them ingredients of concern for anyone dealing with chronic shedding or scalp irritation.

Benzophenones (e.g., BP-1, BP-2, BP-3 (Oxybenzone), BP-4)
Benzophenones are chemical compounds commonly used in shampoos, conditioners, and other personal care products to protect formulas from UV light damage. Benzophenone-3, also known as Oxybenzone, while banned in the EU, is one of the most frequently used types. It is used to preserve product integrity and extend shelf life, however it comes with risks of hormone disruption by mimicking estrogen in the body. Studies suggest that benzophenones may be absorbed through the skin. Environmental concerns are also significant: benzophenones have been implicated in coral bleaching and aquatic toxicity, prompting bans in regions like Hawaii.

Drying Alcohols (Isopropyl, Ethanol, Denatured Alcohol)

Short-chain alcohols like isopropyl alcohol, ethanol, and denatured alcohol are commonly added to shampoos to dissolve ingredients, act as preservatives, or help break down excess oil and buildup on the scalp.

Over time, they strip the scalp and hair of essential natural oils that are critical for hydration and protection. This can lead to dryness, flakiness, and a disrupted scalp barrier, making it harder for hair follicles to anchor strands or receive nutrients. The result? Hair that becomes brittle, breaks more easily, and may eventually thin or shed at a faster rate.

Their drying and follicle-disrupting effects might not be noticeable immediately, but over the months and years, they can slowly degrade the condition of both your scalp and hair shaft - creating the perfect storm for breakage, dullness, and long-term hair loss.

Diethanolamine (DEA) & Triethanolamine (TEA)

DEA and TEA are used to create creamy lathers and stabilize the pH of shampoos. However, these chemicals can react with other ingredients to form nitrosamines - known carcinogens. Long-term exposure to nitrosamines may impact skin and follicular health, potentially leading to irritation, inflammation, and hair loss. Due to rising health concerns, many countries have started regulating or banning DEA and TEA in cosmetics, yet they still appear in many popular shampoo brands.

Silicones (e.g., Dimethicone - D4 (Octamethylcyclotetrasiloxane),  D5 (Decamethylcyclopentasiloxane), D6 (Dodecamethylcyclohexylsiloxane) )

Silicones are added to shampoos to give your hair that smooth, glossy finish - the kind that mimics the “just stepped out of the hairdresser’s” finish. They coat the hair shaft, sealing in moisture and helping reduce frizz. But over time, they also seal out nutrients and cause buildup that weighs hair down and clogs follicles. This can result in dry, brittle strands that break easily and a scalp environment that’s not conducive to new growth. Silicones don’t wash out easily, so unless you're using a clarifying shampoo regularly (which brings its own risks), they can accumulate quickly.  Only California and the EU have implemented formal bans, other countries have adopted varying degrees of regulation concerning silicones in cosmetics. The EU’s regulation is set to take effect on June 6 2027.

Cocamidopropyl Betaine

This foaming agent, derived from coconut oil, is often marketed as a gentler alternative to sulfates. However, it has been linked to allergic reactions and contact dermatitis, especially in those with sensitive or reactive skin. These inflammatory reactions may not only make shampooing uncomfortable but could also contribute to scalp damage and hair thinning over time. If you're experiencing itching or flaking after washing, this ingredient could be a silent trigger.

Triclosan

Triclosan was once a staple in “antibacterial” personal care products, including some shampoos. It has since fallen out of favor, with mounting concerns over its impact on hormone function and the environment. Triclosan has been linked to endocrine disruption, which may indirectly contribute to hair thinning and loss, particularly when hormonal imbalance is already a concern. In addition, its overuse has been tied to antibiotic resistance and inflammation, both of which can worsen scalp health. Though banned in some regions, it may still appear in imported or older stock products - so always check your labels.

Ammonium Lauryl Sulfate (ALS)

Often considered a milder alternative to SLS, Ammonium Lauryl Sulfate (ALS) is another foaming agent used in shampoos to remove oils and dirt. Despite being slightly less irritating, ALS can still strip the scalp of essential lipids, leading to dryness and inflammation. The resulting irritation can disrupt follicular health and lead to increased hair shedding over time. Like its sulfate cousins, it may be especially problematic for people with curly, fine, or chemically treated hair, which tends to be more fragile.

Sodium Hydroxymethylglycinate

Sodium Hydroxymethylglycinate is a preservative that acts as a formaldehyde releaser. While used in low concentrations, it slowly releases small amounts of formaldehyde over time to prevent microbial growth in shampoos. This slow release can lead to scalp irritation, redness, or allergic reactions in sensitive individuals. Continuous exposure may disrupt the scalp’s balance and contribute to a decline in follicular health, possibly triggering or worsening hair thinning. Given its

What About the Ingredients That Don’t Directly Cause Hair Loss?

Not all concerning shampoo ingredients directly attack your hair follicles or halt growth - some have a more subtle or indirect effect on scalp and hair health. These ingredients may not be inherently toxic or strongly linked to hair loss in clinical studies, but they can still dry out the scalp, trigger allergic reactions, or contribute to an unhealthy environment for your follicles. In people with sensitive skin or existing scalp issues, these factors may still lead to inflammation or shedding over time.

If your scalp is healthy and you're not experiencing issues, these may not pose a problem. However, if you're noticing flaking, irritation, or excessive shedding, they’re still worth evaluating - especially in combination with other harsher ingredients.

Phenoxyethanol

Phenoxyethanol is another preservative used to extend the shelf life of shampoos and other cosmetics. It helps keep products bacteria-free but may cause redness, itching, or irritation in some users - especially those with sensitive scalps. While there’s no strong evidence linking phenoxyethanol directly to hair loss, the chronic inflammation it can cause in some individuals may indirectly impact hair health over time.

Propylene Glycol

Propylene glycol is commonly added to shampoos as a humectant to retain moisture. It is generally safe in small quantities, but in higher concentrations, it can cause skin irritation and allergic reactions. While not a direct cause of hair loss, ongoing irritation from propylene glycol can weaken the scalp’s health, possibly contributing to an environment that is less conducive to growth.

Polyethylene Glycols (PEGs)

PEGs are used in shampoos as thickeners and emulsifiers. While PEGs themselves are relatively inert, the manufacturing process can introduce contaminants such as 1,4-dioxane and ethylene oxide - both of which are potentially carcinogenic and irritating to the skin. Though not direct causes of hair loss, repeated exposure to contaminated PEGs may harm the scalp’s barrier function, indirectly affecting follicular health.

EDTA (Ethylenediaminetetraacetic Acid) and Its Salts

EDTA and its salts, like disodium EDTA or tetrasodium EDTA, are commonly used in shampoos as chelating agents to bind metal ions and improve product stability. While they help prevent discoloration and spoilage, EDTA compounds can disrupt the natural balance of minerals on your scalp and hair. By stripping away essential trace elements, they may weaken hair structure over time and interfere with nutrient absorption. Though not directly linked to hair loss in clinical studies, their potential to alter scalp health and contribute to dryness or irritation makes them ingredients worth reconsidering - especially if your scalp is already sensitive or prone to imbalance.

Polyquaterniums (e.g., Polyquaternium-10, -12, -7)

Polyquaterniums are a group of synthetic conditioning agents commonly used in shampoos and conditioners to reduce static, smooth frizz, and give hair a soft, coated feel. While they aren’t directly linked to hair loss or hormone disruption, they can create a film on the hair and scalp that builds up over time. This buildup may clog follicles, weigh hair down, and interfere with the natural balance of oils and moisture. In some individuals, especially those with sensitive scalps, polyquaterniums can also trigger irritation or itching. Additionally, as non-biodegradable synthetic compounds, they raise environmental concerns and are often avoided in truly clean or natural formulations.

Conclusion: Be Ingredient-Aware, Not Ingredient-Fearful

While not every ingredient in your shampoo is out to sabotage your scalp and hair, many commonly used ones do carry risk. Harsh surfactants, hormone disruptors, and known allergens can set off a chain of inflammation, imbalance, and follicular stress that contributes to thinning and breakage.

The best way to protect your hair is to read labels, avoid unnecessary chemical exposure, and prioritize formulas that use gentle nourishing plant ingredients. Whether you're actively trying to reverse hair thinning or simply maintain what you have, being informed is the first and best step.

For those ready to ditch the buildup, irritation, and synthetic fillers, our natural shampoos are crafted with plant-sourced ingredients that nourish the scalp, support healthy growth, and leave your hair feeling genuinely clean.