Is Your Shampoo Harming Your Hair?

Do some ingredients in shampoo do more harm than good? Is shampoo even necessary?

Here, dive into why some hair-washing ingredients can be damaging to hair and health, which shampoo ingredients to avoid, and what experts say about over-washing.

Shampoos also clean the scalp and hair of environmental pollutants, germs, and odors, says Shari Lipner MD, PhD, an associate professor of clinical dermatology and dermatologist at NewYork-Presbyterian and Weill Cornell Medicine in New York City. “The challenge is to remove just enough oils so that the hair looks, feels, and smells clean, but leaves behind enough conditioning agents to leave the hair soft, shiny and manageable.”

There are several common ingredients that are found in most shampoos, says Rebecca Kazin, MD, a dermatologist and the director of clinical research at Icon Dermatology and Aesthetics in North Bethesda, Maryland. She says these include:

• Surfactants These are the primary cleaning agents in shampoos that help to break down oils and dirt and allow these substances to be washed away.
• Conditioning Agents These ingredients help to soften the hair, making it easier to manage.
• Thickeners These ingredients give shampoo its desirable consistency.
• Preservatives These prevent microbial growth and extend the shelf life of shampoo.
• PH Adjusters These help maintain the pH balance in shampoo, which is important for hair and scalp health.
• Fragrance and Colorants These ingredients aren’t essential, but they enhance user experience by providing a pleasant look and scent to shampoo.
• Botanical Extracts and Oils These can provide additional benefits such as moisturizing properties or soothing effects.

Some ingredients frequently used in shampoo can be harmful to your hair or even your health.

Shampoo Ingredients That Can Hurt Hair

Experts say skip shampoos with these ingredients, as they may be damaging to hair.

1. Alcohol (Some of Them)

That said, fatty alcohols like cetyl alcohol, stearyl alcohol, and cetearyl alcohol have the opposite effect. “They help condition the hair and retain moisture,” says Dr. Kopelman, who notes that fatty alcohols can be especially helpful for people with dry or damaged hair.

2. Coal Tar 

People who are pregnant or breastfeeding should avoid coal tar in psoriasis shampoos and hair dyes altogether, given the lack of research on its effects in this group, Kazin says.

3. Polyethylene Glycols 

4. Selenium Sulfide

“I generally advise patients to limit their use of selenium sulfide to two to three times per week at most,” Kopelman says. If your scalp becomes more sensitive or you notice hair thinning, alternate the selenium sulfide shampoo with a gentler shampoo that contains zinc pyrithione or tea tree oil, suggests Kopelman.

5. Silicones 

• Dimethicone
• Phenyl trimethicone
• Cyclomethicone
• Cyclopentasiloxane
• Cyclohexasiloxane

Shampoo Ingredients That May Be Damaging to Overall Health

Many shampoo ingredients that can be harmful to the hair and to overall health have become much less common as research by dermatologists has highlighted the risks and products have been reformulated, says Mary Lupo, MD, a dermatologist at the Lupo Center for Aesthetic & General Dermatology in New Orleans.

But several potentially harmful ingredients are still regularly found in shampoos, including the following.

1. Benzene

• Benzene
• Toluene
• Methylbenzene
• Phenylmethane
• Toluol

2. Resorcinol

“Ultimately, it’s about balancing effectiveness with safety, and for patients with chronic scalp conditions, I encourage discussing options with a dermatologist or hair specialist,” Kopelman says.

• Resorcinol
• 1,3-benzenediol
• Resorcin
• 1,3-dihydroxybenzene

3. Diethanolamine

4. Triclosan

5. Formaldehyde and Formaldehyde-Releasing Preservatives

• Quaternium-15
• Imidazolidinyl urea
• Diazolidinyl urea
• Polyoxymethylene urea
• Sodium hydroxymethylglycinate
• Glyoxal

6. Parabens

In addition, research shows that parabens are less likely than other preservatives to cause allergic reactions, Kazin says.

• Butylparaben
• Ethylparaben
• Methylparaben

7. Synthetic Fragrances

“Fragrance blends often contain dozens of unlisted chemicals, which makes it difficult to determine exactly what you’re putting on your scalp,” says Kopelman. “While not everyone will have a reaction, I recommend patients opt for fragrance-free or naturally scented shampoos when possible, especially if they have scalp sensitivity, hair thinning, or hormonal concerns.”

To determine whether a shampoo has synthetic fragrance, Kopelman suggests checking the ingredient list for terms like “fragrance” or “parfum.”

8. Phthalates

• Butyl benzyl phthalate (BBP)
• Diethyl phthalate (DEP)
• Diisodecyl phthalate (DIDP)
• Diisononyl phthalate (DINP)
• Dihexyl phthalate (DHP)
• Dioctyl phthalate (DNOP)

9. Sulfates

• Ammonium lauryl sulfate
• Sodium lauryl sulfate (SLS)
• Sodium laureth sulfate (SLES)

Even if your shampoo is free of the harmful ingredients above, you still don’t want to overdo it. Over-shampooing, or washing too frequently, can leave you with frizzy, dry, or dull hair. “When you over-shampoo, the hair and scalp can become drier and, hence, more irritated,” Lindsey Bordone, MD, a board-certified dermatologist and an assistant professor of dermatology at Columbia University Irving Medical Center in New York City.

Forgoing shampoo sometimes leads people to load up on products such as dry shampoo to extend how long they can go without washing the hair, and that can create even more buildup on the scalp, Dr. Bordone says. “This can also lead to irritation from the product residue,” she says.

Experts say how often you wash your hair should depend on a variety of factors, including your hair type and your lifestyle.

Here are a few tips to best care for your hair.

1. Read product labels. Cross-check the ingredients listed on your shampoo bottle with those to avoid. Some ingredients, such as sulfates and parabens, may be bad for your hair and your overall health.

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2. Look for healthier ingredients. Beneficial ingredients include biotin to strengthen hair and promote growth, keratin to repair and strengthen damaged hair, panthenol (vitamin B5) to moisturize and add shine, and natural oils like argan oil, coconut oil, or jojoba oil as another way to add moisture and shine, Kazin says.
3. Don’t get too hung up on the price of your shampoo. You don’t necessarily need to spend a ton of time washing your hair or a lot of money on shampoo to get the results you want. “More expensive is not necessarily better,” Dr. Lipner says. “More expensive shampoos may have higher concentrations of conditioners, but since most people use a conditioner anyway, less-expensive shampoos cleanse the hair well and are fine to use.”
4. Find the right washing frequency. There’s no tried-and-true recommendation for how often to shampoo your hair. The right frequency depends on your ethnicity, hair density, thickness, and growth rate, Bordone says. For example, oily hair may need washing daily or every other day, while dry hair may only need to be washed twice weekly, Kazin says. Curly hair can also be washed less frequently, sometime as little as once a week, Kazin adds.

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5. Use your fingertips to wash. Use your fingertips to get a good lather from shampoo and scrub your scalp, Dr. Lupo says. If you use your fingernails, this can disrupt the protective layer on your scalp that maintains proper hydration, Lupo says.

• Shampoo is designed to remove oil, sweat, product buildup, and dirt from your hair and scalp without leaving a residue on your hair when mixed with hard water.
• Some shampoo ingredients can be harmful to your hair and overall health.
• Over-washing the hair can also cause issues, including hair dryness and breakage and scalp irritation.

Additional reporting by Lisa Rapaport and Lauren Bedosky.