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What Ingredients Are Bad For Hair?

Kristin Hall

Reviewed by Kristin Hall, FNP

Written by Nicholas Gibson

Published 03/21/2022

Updated 03/22/2022

The right shampoo, conditioner and other hair care products are essential for keeping your hair clean, strong and full of life. But knowing what to look for — and just as importantly, which active ingredients to look out for — can be confusing.

While many ingredients in shampoos and conditioners can nourish and strengthen your hair and scalp, others can cause dry hair, skin irritation and serious hair shaft damage. Some ingredients may even contribute to hair loss or worsen acne breakouts around your scalp and hairline.

Below, we’ve listed harmful ingredients to avoid when you’re shopping for shampoo, conditioner or other hair care and styling products. We’ve also discussed several other common sources of damage to your hair, including harmful hair care habits that you’ll want to avoid. 

Finally, we’ve shared how you can make effective use of hair care products while reducing your risk of allergic reactions, hair damage, shedding and other common problems. 

There are three key components to healthy hair. The first is your hair itself — that is, the strands of hair that grow out of your scalp. The second is a healthy scalp, which contains the hair follicle structures that support optimal hair growth.

The third is a healthy body, which supplies your scalp and hair follicles with the nutrients needed to facilitate hair growth and prevent issues that can stunt the growth of your hair.

When it comes to ingredients in shampoos, conditioners and other hair care products, the good news is that most aren’t overly harmful. In fact, from exotic ingredients like jojoba oil to everyday natural cleansing agents, most shampoo and conditioner ingredients are fine for your hair.

However, there are a few that are best avoided all the time, as well as a few more that you may want to avoid in specific circumstances. We’ve shared these below, along with why each is best avoided when you’re shopping for hair care products.

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Sulfates, such as sodium lauryl sulfate, sodium laureth sulfate and ammonium lauryl sulfate, are commonly used as foaming and cleansing ingredients in shampoos and other hair and personal care products.

These sulfates belong to a group of chemical compounds called surfactants, which are great for stripping away extra sebum (a type of natural oil secreted by your sebaceous glands) from your scalp and hair follicles.

Sulfates aren’t necessarily harmful chemicals, and they do have their benefits. However, some people find that shampoos that contain sulfates cause hair to become harsh, dull and prone to issues such as tangling.

Some common sulfates are also linked to skin irritation in people with sensitive skin conditions, such as rosacea.

Contrary to popular belief, sulfates aren’t toxic ingredients that can increase your risk of cancer or other diseases, especially not in the small quantities used in hair products. However, if you have sensitive skin and want to avoid potential irritation, they’re generally best avoided.

Artificial Fragrances

Although the fragrances used in some shampoos and hair care products aren’t always harmful to your hair, they can cause irritation and trigger some common skin allergies.

Research has found that many fragrances used in skin and hair care products have allergenic potential, meaning they can cause sensitization and allergic reactions. However, the risk with most hair care products appears to be lower than with leave-on cosmetic products. 

If you get contact dermatitis from products that contain fragrances, or if you have a skin issue such as rosacea, try looking for hair products that are labeled “fragrance-free.” Avoid products that are simply labeled “unscented,” as these can often still irritate a dry scalp.


Parabens are common chemicals that are used as preservatives in makeup, skin care and hair care products. They work by stopping the growth of microorganisms, such as mold and bacteria, that can potentially cause infections when applied to your skin.

Common parabens in hair care products and cosmetics include propylparaben, methylparaben, ethylparaben and butylparaben.

Most hair products only contain small amounts of parabens, and the overall health effects of the parabens used in these products are largely unknown. Research suggests that parabens are at least partly absorbed by the body and can be found in most people’s urine.

While parabens aren’t widely viewed as having seriously harmful health effects, some research suggests that they can act as endocrine disruptors — chemicals that affect your body’s ability to produce endocrine hormones such as estrogen, progesterone and thyroid hormone.

Formaldehyde, Formalin and Methylene Glycol

Formaldehyde is a strong-smelling, colorless gas that can cause problems such as watery eyes, burning, coughing, wheezing and nausea if inhaled. It’s also classified as a carcinogen that may contribute to an increased risk of cancer, according to the National Cancer Institute.

Although formaldehyde isn’t typically used in shampoos and conditioners, it’s used in some hair smoothing products that are used to straighten hair and remove curls.

When these products are applied with heat, they can release formaldehyde (also referred to as formalin and methylene glycol). This may cause health issues if these products aren’t used in a properly ventilated environment.

If you’re exposed to formaldehyde from a hair smoothing treatment, you may develop an allergic reaction that affects your eyes, nose and/or lungs. Formaldehyde is also a skin irritant that may cause you to develop a rash, cough and other symptoms.

To avoid products that contain formaldehyde, ask your stylist before you get any hair smoothing or straightening treatment. You can also check the ingredient list of any product for substances such as formaldehyde, formalin or methylene glycol.

Bleaches and Hair Color Products

If you have black or dark brown hair that you lighten — whether at home or at the salon — you’ve probably exposed your hair to bleach. Common chemicals used to bleach hair include hydrogen peroxide and ammonium persulfate.

Most chemical bleaches work quickly to lighten your hair, but in doing so, they can cause major structural damage to your hair strands.

For example, research using scanning electron microscopy (SEM) shows that hairs bleached to a yellow color have irregular, lifted cuticle scales. The bleached hairs also displayed differences in tensile strength and length.

Beyond harming your hair, many ingredients in bleaches and artificial colors can also harm your scalp.

Bleaching ingredients like hydrogen peroxide are caustic chemicals, and when they’re applied to your scalp for too long or in excessive amounts, they can cause chemical reactions that result in a sensitive scalp, itching and irritant dermatitis.

While rare, there are even case reports of people developing deep burns after getting bleaching and colored hair procedures performed in hairdressing salons.

Although it’s okay to color your hair occasionally, it’s important to be careful whenever you apply bleaching agents (or, preferably, get them applied professionally in a salon). Choose your stylist wisely and take it slow and steady, meaning don’t try to change too much at once. 

It’s also best to limit how often you apply synthetic colors. According to the American Academy of Dermatology, you can limit damage by leaving eight to 10 weeks between each time you use coloring products to touch up your hair.


Many shampoos, hair conditioners and styling products contain oils that help to shield your hair from damage and keep it smooth, soft and full of volume.

While normal amounts of oil won’t necessarily damage your hair, the oils used in some hair care products can potentially clog your hair follicles and contribute to acne breakouts that develop on your scalp and around your hairline.

You can usually identify acne breakout-causing products by checking the ingredients list for oils or natural fats, such as shea butter. Often, switching to a product labeled “non-comedogenic” or “oil-free” will be enough to stop acne breakouts and get your skin back under control.

Our guide to forehead acne shares other techniques that you can use if you’re prone to pimples on your forehead and around your hairline. 

It’s not just harmful ingredients that can damage your hair — the wrong hair care habits, styling techniques and even lifestyle factors can also contribute to issues such as brittle hair, thinning and scalp irritation.

Some of these habits and styling techniques may also make the effects of some ingredients in hair care products more severe.

In addition to avoiding the ingredients listed above, try to stay aware of the following common sources of hair damage.

Prolonged Exposure to Heat 

Excessive heat can damage your hair. In fact, research shows that even using a hairdryer set to a standard temperature can damage your hair when it’s held close to your scalp, with higher temperatures increasing the degree of damage to the hair cuticle. 

Other styling devices that directly apply heat to your hair, such as hair straighteners and curling irons, can also affect your hair health.

To reduce heat-related hair damage that leaves you with weak, frizzy hair, try to limit your use of products that expose your hair to excessive heat. 

This means choosing the low or medium setting on your straightener or curling iron and using it no more than once every other day. Research also shows that holding a hairdryer at least six inches from your scalp and moving it in a continuous motion limits damage to your hair. 

Excessive Brushing or Combing

Believe it or not, brushing your hair 100 times a day doesn’t stimulate growth — in fact, it’s much more likely to prevent you from maintaining healthy hair.

Excessive hair brushing can contribute to split ends — an issue that occurs when the tips of your hair dry and become frayed. Brushing wet hair can be particularly harmful, as your hair is more likely to break when it’s wet.

There’s one exception to this rule — if you have curly hair or textured hair, brushing when wet is actually helpful for preventing breakage. 

In any case, it’s best to only brush your hair when you need to, such as before important events or other occasions when knots and tangles just aren’t acceptable. 

Spending Time in the Sun

Just like long-term sun exposure can damage your skin and speed up the effects of aging, it can also damage your hair. 

UV radiation from the sun can be especially damaging if you use bleach, hair dyes or other hair treatments that break down the bonds of keratin in your hair. In these cases, even a mild level of sun exposure could cause you to develop brittle, dry hair.

To limit the combined effects of sun exposure and chemical dyes, apply a leave-in conditioner to your hair before you spend any time outdoors in bright, direct sunlight. It also helps to cover up your hair by wearing a hat whenever possible.

Once you know which ingredients to avoid, maintaining great hair is all about striking the perfect balance between active hair care and a good lifestyle. Use the tips below to make better buying decisions and take better care of your hair:

  • Check product labels for unwanted ingredients. While most shampoos don’t contain toxic chemicals, the harmful ingredients listed above aren’t uncommon, even in products marketed as using natural ingredients. If you’re at the drug store or online, make sure to check product labels for any unwanted ingredients before you buy anything.

  • Consider using an anti-shedding shampoo. If you’re prone to hair shedding, the right shampoo can make all the difference. Our Triple Threat Shampoo is designed to prevent hair loss while keeping your hair hydrated, fresh and healthy.

  • If you’re losing hair, take action. Hair loss is common, and it has the potential to affect you at any age. If you’re losing hair, our guide to the best hair loss products for women is an invaluable resource for learning more about your treatment options.

  • Practice healthy hair care habits. The right hair products won’t make up for bad habits or an unhealthy lifestyle. Our guide to growing thicker hair shares 12 easy steps that you can follow for healthier natural hair, regardless of your specific hair type.

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Avoiding artificial fragrances, sulfates and other ingredients can help you to minimize damage to your scalp and hair, especially if you have sensitive skin or a specific skin condition. 

Interested in learning more about taking care of your hair? Our list of simple hair tips for different hair types covers how you can choose hair products and styling techniques based on your hair’s unique needs and characteristics.

You can also view our full range of hair care products for women online, including our Complete Hair Kit for stimulating growth and healthier hair and our Salon Strength System for maximizing your hair’s fullness, density and strength from every possible angle. 

20 Sources

Hims & Hers has strict sourcing guidelines to ensure our content is accurate and current. We rely on peer-reviewed studies, academic research institutions, and medical associations. We strive to use primary sources and refrain from using tertiary references.

  1. D’Souza, P. & Rathi, S.K. (2015, May-June). Shampoo and Conditioners: What a Dermatologist Should Know? Indian Journal of Dermatology. 60 (3), 248–254. Retrieved from
  2. 6 Rosacea Skin Care Tips Dermatologists Give Their Patients. (n.d.). Retrieved from
  3. Bondi, C.A., et al. (2015). Human and Environmental Toxicity of Sodium Lauryl Sulfate (SLS): Evidence for Safe Use in Household Cleaning Products. Environmental Health Insights. 9, 27-32. Retrieved from
  4. Dreschel, D.A., et al. (2018, November-December). Skin Sensitization Induction Potential From Daily Exposure to Fragrances in Personal Care Products. Dermatitis. 29 (6), 324-331. Retrieved from
  5. 6 Rosacea Skin Care Tips Dermatologists Give to Their Patients. (n.d.). Retrieved from
  6. How to Care for Your Skin in Your 60s and 70s. (n.d.). Retrieved from
  7. Parabens in Cosmetics. (2020, August 24). Retrieved from
  8. Parabens Factsheet. (2017, April 7). Retrieved from
  9. Nowak, K., Ratajczak-Wrona, W., Górska, M. & Jabłońska, E. (2018, October 15). Parabens and their effects on the endocrine system. 474, 238-251. Retrieved from
  10. Hughes, E.C. & Saleh, D. (2021, June 8). Telogen Effluvium. StatPearls. Retrieved from
  11. Hair Smoothing Products That Release Formaldehyde When Heated. (2021, March 11). Retrieved from
  12. Formaldehyde and Cancer Risk. (2011, June 10). Retrieved from
  13. Hair bleach poisoning. (2019, October 3). Retrieved from
  14. Jeong, M.-S., Lee, C.-M., Jeong, W.-J., Kim, S.-J. & Lee, K.-Y. (2010, October). Significant damage of the skin and hair following hair bleaching. The Journal of Dermatology. 37 (10), 882-7. Retrieved from
  15. Forster, K., et al. (2012, December 31). Hair bleaching and skin burning. Annals of Burns and Fire Disasters. 25 (4), 200–202. Retrieved from
  16. How to Stop Damaging Your Hair. (n.d.). Retrieved from
  17. Are Your Hair Care Products Causing Breakouts? (n.d.). Retrieved from
  18. Hair Styling Without Damage. (n.d.). Retrieved from
  19. Lee, Y., et al. (2011, November). Hair Shaft Damage from Heat and Drying Time of hairdryer. Annals of Dermatology. 23 (4), 455–462. Retrieved from
  20. Coloring and Perming Tips for Healthier-Looking Hair. (n.d.). Retrieved from

This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment. Learn more about our editorial standards here.

Kristin Hall, FNP

Kristin Hall is a board-certified Family Nurse Practitioner with decades of experience in clinical practice and leadership. 

She has an extensive background in Family Medicine as both a front-line healthcare provider and clinical leader through her work as a primary care provider, retail health clinician and as Principal Investigator with the NIH

Certified through the American Nurses Credentialing Center, she brings her expertise in Family Medicine into your home by helping people improve their health and actively participate in their own healthcare. 

Kristin is a St. Louis native and earned her master’s degree in Nursing from St. Louis University, and is also a member of the American Academy of Nurse Practitioners. You can find Kristin on LinkedIn for more information.

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