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When it comes to shampoo, there’s a buffet in every store full of different products to choose from. Some offer shine, others hydration, and all the promise of cleanliness.

With such lengthy lists full of hard-to-pronounce ingredients, it’s hard to know what you’re really slathering onto your hair.

It’s important to get to know the ingredients you’re washing your locks with, especially when some can cause irritation or buildup.

Whether you have curly, dyed, straight, or oily hair, there’s a lot to get your head around (pun intended).

Whether it’s a tried-and-true skin care regimen, how often you wash your hair, or the cosmetics you’re curious about, beauty is personal.

That’s why we rely on a diverse group of writers, educators, and other experts to share their tips on everything from the way product application varies to the best sheet mask for your individual needs.

We only recommend something we genuinely love, so if you see a shop link to a specific product or brand, know that it’s been thoroughly researched by our team.

Healthline

Most shampoos are formulas that contain roughly 10 to 30 different ingredients.

All shampoos need to contain a detergent or cleansing agent in order to sufficiently rid the scalp of oil, dirt, sebum buildup, and odor. They work by lifting impurities from the scalp to be washed away by water.

Common detergents in shampoo are surfactants, including sodium lauryl sarcosinate, sodium lauryl sulfate (SLS), and sodium laureth sulfate (SLES). These surfactants work alongside cosurfactants, such as cocamidopropyl betaine.

Common ingredients in shampoo include:

  • surfactants
  • foaming agents
  • conditioners
  • thickeners
  • opacifiers
  • sequestering agents
  • preservatives
  • special additives
  • fragrance

Common shampoo thickeners include:

  • cetyl alcohol
  • stearyl alcohol
  • carnauba wax
  • xanthan gum
  • gelatin
  • stearic acid

Two common pH regulators are citric acid or glycolic acid. Sequestering agents that prevent scum from forming on hair include polyphosphates and ethylenediaminetetraacetic acid.

Then there are preservatives, which prevent bacteria formation.

Common preservatives include:

  • sodium benzoate
  • 1,3-dimethylol-5,5-dimethyl (DMDM) hydantoin
  • tetrasodium EDTA
  • methylisothiazolinone
  • potassium sorbate
  • sorbic acid
  • dehydroacetic acid
  • benzyl alcohol

Finally, shampoos may contain a form of vitamin B5 called panthenol, the moisture-retaining humectant glycol, and fragrance for a pleasant smell.

For instance, Dove’s Nutritive Solutions Daily Moisture Shampoo and Pantene Daily Moisture Renewal Shampoo are two popular shampoos.

They both contain sodium laureth sulfate as the cleansing agent and cocamidopropyl betaine as the thickener, as well as fragrance and citric acid to balance pH.

Shop for Dove’s Nutritive Solutions Daily Moisture Shampoo and Pantene Daily Moisture Renewal 2-in-1 Shampoo and Conditioner online.

Sulfates

Sulfates are chemicals used as cleansing agents in shampoo. The most common are sodium lauryl sulfate and sodium laureth sulfate.

Sulfates offer a deep clean and cause the lathering effect in shampoos. If your shampoo doesn’t lather, there’s a good chance it’s sulfate-free.

However, the harsh cleansing quality of sulfates may cause skin irritation, skin dryness, and inflammation.

Sulfates may increase skin sensitivity and worsen existing conditions, such as rosacea, eczema, and contact dermatitis. They may also irritate sensitive skin.

Sulfates can strip hair of natural oils and cause dryness. They may also damage hair by disrupting natural sebum production.

Formaldehyde

Formaldehyde is a chemical compound used in household products, building materials, and as a preservative in some consumer products, including shampoo.

Formaldehyde is known to cause contact allergy and has been shown to induce dermatitis. It’s also been shown to worsen existing allergic dermatitis and eczema.

The Department of Health and Human Services lists formaldehyde as a known human carcinogen. Studies of workers exposed to high levels of the chemical compound found it can cause myeloid leukemia and rare cancers, including sinus and throat cancer.

Parabens

Parabens are chemical preservatives that have long been used in beauty products to increase shelf life.

Studies have shown that parabens can quickly be absorbed through the skin and penetrate into bodily tissues. This can cause allergic contact dermatitis and skin issues such as redness, irritation, itchy skin, flaking, and hives.

Evidence also suggests that parabens can have estrogenic effects. They may interfere with the body’s normal hormone regulation, which can affect pregnancy and menstruation.

Parabens have also been shown to affect breast cell tissue and increase susceptibility to breast cancer.

Hexachlorophene

Hexachlorophene is an antiseptic agent used in cosmetic products for its antibacterial qualities.

The compound can cause eye and skin irritation and, if swallowed, nausea, vomiting, abdominal cramps, and diarrhea.

Other side effects may include skin redness, dryness, scaling, skin swelling, and sensitivity to light.

Phthalates

Phthalates are a group of chemicals commonly used to make plastic more flexible. They’re used as a binding agent in cosmetic products, including shampoo.

Phthalates have been linked to disrupted hormones and infertility, lower sperm count, and reproductive and genital defects. Studies show that exposure may increase risk of pregnancy loss and gestational diabetes.

Further research suggests that phthalates may harm the kidneys, thyroid, immune system, and liver.

Shampoo ingredients to avoid include:

  • sulfates
  • formaldehyde
  • parabens
  • hexachlorophene
  • phthalates

If you want a sulfate-free shampoo, you’ll still need to make sure there’s a cleansing agent in the product.

Sulfate-free ingredients include:

  • sarcosines
  • sulfosuccinates anionic detergents
  • betaines
  • sultaines
  • imidazolinium derivatives

Sulfate-free cleansing agents include:

  • sodium lauryl sulfoacetate (SLSA)
  • sodium cocoyl glycinate
  • sodium cocoyl glutamate
  • disodium
  • sodium lauroyl methyl isethionate
  • sodium lauroyl taurate
  • sodium lauroamphoacetate
  • decyl glucoside
  • lauryl glucoside

A shampoo is considered natural when it’s sulfate-free and includes organic and plant-based ingredients.

Instead of synthetic ingredients, natural shampoos commonly contain essential oils, fruit extracts, botanicals, and certified-organic ingredients.

Ingredients that are plant-based are generally considered mild, including seed oils and fruit extracts. They’re less likely to disrupt the hair and scalp’s natural pH and oil balance.

Still, be sure to test for allergies before using an ingredient you may be sensitive to.

Natural ingredients to look for:

These natural ingredients are gentler on the hair and scalp, as they don’t strip the hair cuticles while cleansing. They also help with hydration while still providing a good clean.

By comparison, chemicals found in some shampoos can strip hair oil, causing damage.

Modern-day shampoos have gone well beyond containing simple cleaning agents. They now incorporate ingredients to target specific issues or hair types.

Hair loss and thinning hair

Hair loss or hair thinning can be caused by a variety of reasons. There are multiple shampoo ingredients to look for depending on the source of the issue.

Phyto-caffeine has been shown to help reduce hair thinning, especially for female pattern baldness.

Minoxidil is an FDA-approved ingredient for treatment of hair loss when used as a 2 percent topical solution.

Niacin (vitamin B-3) can help improve circulation, which increases the flow of nutrients to hair follicles, and helps with hair growth and fullness.

Animal studies have suggested lavender and peppermint oil may be effective for hair growth, but more research is needed to confirm whether this works for humans.

To prevent environmental damage, the amino acid histidine absorbs excess copper from hair, which helps to shield it from UVA and UVB damage.

Beneficial shampoo ingredients for thinning hair include:

  • phyto-caffeine
  • minoxidil
  • niacin
  • histidine
  • essential oils like lavender and peppermint may help, but more research is needed

Curly, wavy, and coily hair

Those with curly or wavy hair should look for shampoos that are hydrating, contain frizz-reducing ingredients, and are free from deep-cleansing surfactants, such as sulfates.

Those with coily hair, or voluminous strands that form compact curls, spirals, or ringlets in a zig-zagged or pleated pattern from the scalp, should aim for a shampoo that offers lots of moisture and hydration.

Glycerin is a clear natural compound that’s used widely in cosmetic products for its moisturizing qualities. It draws moisture from the air into hair and retains it, resulting in less frizz and more defined, shiny curls.

Oils and butters, such as shea butter, jojoba oil, coconut oil, sunflower oil, and argan oil, can help hydrate hair and keep curls and waves smooth and glossy.

Seed oils, such as Abyssinian seed oil, grapeseed oil, and blackseed oil, are another beneficial ingredient for curly, wavy, and coily locks. These are super light oils that are easily absorbed. They help to detangle strands while moisturizing.

Beneficial shampoo ingredients for curly, wavy and coily include:

  • glycerin
  • essential oils and butters
  • seed oils

Straight hair

Those with straight hair may be looking to add volume. If that’s the case, you should look for coconut, soybean, almond, and sunflower oils as well as vitamins B5, C, and E, which are all said to add volume and body.

Similarly, proteins such as anionic and cationic polymers, rice, and corn, help to bind hair and create fullness.

Another beneficial ingredient for those with straight hair is keratin, a fibrous structural protein that’s found in the makeup of hair, skin, and nails.

In hair products, keratin works by smoothing down the cells that overlap in hair strands as the hair cuticles absorb the protein, resulting in fuller, smoother, and softer hair.

The use of keratin also makes hair less frizzy and makes it appear straighter. Studies also suggest that active components of keratin can make hair stronger.

Beneficial shampoo ingredients for straight hair:

  • coconut oils
  • soybean
  • almond
  • sunflower
  • vitamins B5, C, and E
  • proteins
  • keratin

Dyed or dry hair

Those with dyed or dry hair can look for shampoos with mild cleansing agents and lots of conditioning ingredients.

Sodium lauryl sulfoacetate is one sulfate-free cleansing option.

Many two-in-one shampoos for dry hair work by replacing sebum with a thin silicone coating to make the hair shaft shiny and smooth.

Shampoos with oils help to nourish and rehydrate hair. These include argan oil, avocado oil, macadamia oil, coconut oil, and olive oil.

Similarly, glycerin is a deep conditioner that can help to retain moisture.

Beneficial shampoo ingredients for dry hair include:

  • mild cleansing agents
  • silicone
  • oils
  • glycerin
  • two-in-one shampoos with silicone

Dandruff

Dandruff shampoos commonly contain fungicides that kill fungi and reduce loose dander. Fungicides include ketoconazole, zinc pyrithione, and selenium disulfide.

For those looking to avoid synthetic fungicides, look for natural ingredients such as tea tree oil or herbal extracts.

Beneficial shampoo ingredients for dandruff include:

  • fungicides like ketoconazole, zinc pyrithione, and selenium disulfide
  • natural fungicides like tea tree oil

Oily scalp

Those with an oily scalp or hair produce excess sebum from overactive sebaceous glands.

Look for shampoos that contain lauryl sulfates or sulfosuccinates for a deep clean.

Too many conditioning agents should also be avoided, as these can contribute to an abundance of oil, even after a wash.

Shampoos with natural ingredients like tea tree oil are also worth a try. Synthetic ingredients may throw off the scalp’s natural sebum production and increase oil production.

Beneficial shampoo ingredients for oily scalps:

  • deep cleansing agents
  • natural ingredients
  • minimal conditioning agents

There are many shampoos on the market that each come with a unique formula full of different, and usually long-named, ingredients.

For best results for your hair, opt for natural, organic, and plant-based ingredients and try to avoid sulfates, parabens, formaldehyde, hexachlorophene, and phthalates.

Get to know your hair type and what ingredients work best for it — you’ll thank yourself for it with healthy, shiny locks.


Marnie Vinall is a freelance writer living in Melbourne, Australia. She’s written extensively for a range of publications covering everything from politics and mental health to nostalgic sandwiches and the state of her own vagina. You can reach Marnie via Twitter, Instagram, or her website.