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DMDM Hydantoin: What is it & Does it Cause Hair Loss?

DMDM Hydantoin is an antimicrobial ingredient and preservative that is often found in shampoos, hair conditioners and skin care products. It prevents the growth of fungi, yeast and bacteria and makes the product last longer. The ingredient has come under the spotlight recently due fears it may cause hair loss. This post looks that what DMDM Hydantoin is and whether you should be worried about it being in your shampoo.

DMDM Hydantoin

How Does DMDM Hydantoin Work?

In order to effectively preserve cosmetic products, DMDM Hydantoin releases small amounts of formaldehyde. This is why it is known as a “formaldehyde donor”. Formaldehyde is a fungicide, germicide, and disinfectant, which effectively preserves the shelf life of products.

DMDM Hydantoin is able to release formaldehyde very slowly over time to stop mould and bacteria growing in your conditioners, hair gels and other cosmetic formulations. It does this gradually over the shelf-life of your product.

Is DMDM Hydantoin dangerous?

A study conducted in 2013 showed that formaldehyde was not dangerous in cosmetics as long as the amounts were kept within safe limits (source).

Other sources however state that formaldehyde releasers can have dangerous health effects even at low levels of exposure, leading to skin irritation, respiratory problems or even cancer (source).

To put things into perspective, the amount of formaldehyde released by DMDM Hydantoin in your hair care products is equivalent to the amount naturally occurring in a medium sized apple or pear. Even if you have a severe formaldehyde allergy it is difficult to see how you could have harmful reactions to such low levels of formaldehyde.

Nevertheless numerous individuals have claimed to have negative side effects following skin contact with products containing the ingredient DMDM Hydantoin. Below is a list of articles which will help you gather further information on the use of formaldehyde releaser preservatives and their safety.

Information Available on the Safety of DMDM Hydantoin

The following sources contain information relating to the safety of DMDM Hydantoin:

Final Report on the Safety Assessment of DMDM Hydantoin – this was first published in the International Journal of Toxicology in 1988

Carcinogens in Cosmetics – information about whether DMDM Hydantoin is a human carcinogen

Formaldehyde in Cosmetics – information about whether formaldehyde exposures even in low concentrations are dangerous.

Why has a class-action lawsuit been filed against TRESemmé?

Two class-action lawsuits have been filed against Unilever who manufacture TRESemmé hair products. The lawsuits claim that Unilever failed to warn their customers that their Keratin Smooth Color Shampoo contained DMDM Hydantoin. They also claim that the ingredient caused hair loss in over one hundred people who were using it.

Unilever however claim that their products are safe and continue to include the ingredient in their shampoos. The lawsuits were filed in the U.S District Courts for the Northern District of California and Northern District of Illinois on November 16, 2020.

The lawsuits are similar to those made against Unilever’s competitor, Suave Keratin Infusion, in 2012 where users claimed that their hair fell out after using keratin treatments (source)

Does DMDM Hydantoin Cause Hair Loss?

DMDM Hydantoin has gained a bad reputation because it is linked to lawsuits where hair loss has been claimed. There are many reasons for hair loss however including underlying medical conditions, vitamin deficiencies or stress. Currently there is also no scientific data to prove any long term side effects from DMDM Hydantoin.

The view online from the medical community appears to be mixed. In some cases I found reports that formaldehyde-releasers can, in rare cases, lead to red, itchy, flaky scalps, and temporarily interfere with functioning hair follicles, leading to shedding (source). There were many other cases however suggesting there was no cause for concern.

What are the Opinions of Professionals in the Industry?

Dr Angelo Landriscina

Dr Angelo Landriscina is a Dermatologist and site director for Dermatology at Mount Sinai Doctors-Brooklyn Heights. He posted the following thread on his Twitter account on New Year’s Day 2021. You can follow him on Twitter: @Dermangelo

DMDM Hydantoin
Dr Angelo Landriscina
Dr Angelo Landriscina

Esther Olu

Esther Olu is a Cosmetic Chemist, Formulator, and Science Communicator. On social media she is known as The Melanin Chemist. Below is her verdict on DMDM Hydantoin. You can follow her on Twitter: @estherolu

DMDM Hydantoin

Jen @theecowell

This instagram account is run by a Cosmetic scientist, science communicator & podcaster with over 70,000 followers. Check out the image below and @theecowell on Instagram to see their opinions on DMDM Hydantoin.

DMDM Hydantoin

What Products Contain Cosmetic Preservatives?

Other than hair care products, the use of use of DMDM Hydantoin is found in many other beauty products including nail polish, bath products, makeup bases and skin care products.

If you would rather avoid this ingredient for the time being you should check the ingredients label for the following preservatives which all release a tiny amount of formaldehyde: Formaldehyde, quaternium-15, dimethyl-dimethyl (DMDM) hydantoin, imidazolidinyl urea, diazolidinyl urea, sodium hydroxymethylglycinate, 2-bromo-2-nitropropane-1,3-diol (bromopol)

The cosmetics industry already labels some nail products as “formaldehyde-free”.

Also avoid using products that have expired or been left in the sun as they may have released more formaldehyde than is safe for human health and may cause allergic reactions in sensitive individuals.

Currently there are over 2,000 products in the United States which contain an antimicrobial formaldehyde releaser preservative. Ensure you do a cosmetic ingredient review on all your personal care products if you want to avoid these preservatives.

Should I Throw Away my Shampoo?

If your current hair products are working well for you then keep using them. Just because other people may have had an allergic reaction to the ingredients in their shampoo doesn’t mean you will too.

DMDM hydantoin is a widely used ingredient in the beauty industry, and you have probably been using it for years unaware and with no problems.

If you use TRESemmé products, the TRESemmé website states that health authorities and regulators have agreed that the amount of DMDM Hydantoin in their products is safe. This includes the US Cosmetic Ingredient Review Expert Panel and Europe’s Scientific Committee on Consumer Safety.

Since so many people have become worried about this particular ingredient however, TRESemmé began removing it from their products some time ago. If you live in the United Kingdom or Ireland most TRESemmé products are now completely free from DMDM hydantoin.

You can view further information on TRESemmé’s website.

If you would rather use a shampoo without DMDM Hydantoin for the time being, the following post lists some great products that are completely free from formaldehyde and DMDM Hydantoin: 17 Shampoos Without DMDM Hydantoin or Formaldehyde

What if You’re Suffering from Hair Loss?

There is a whole section on the UK Beauty Room Hair Care page which looks at ways to manage and treat hair loss and sensitive skin on the scalp. Hair loss can have numerous different causes and is not necessarily caused by adverse effects from preservatives in your hair care products. Some of the causes of hair loss can include:

  • Age
  • Genetics
  • Stress
  • Tight repetitive hairstyles
  • Hormone imbalances
  • Medication
  • Scalp Infections
  • Thyroid Problems
  • Vitamin Deficiencies

More Information

NHS Website – information regarding hair loss causes and treatment

MayoClinic Website – information regarding hair loss symptoms, causes, risk factors, and prevention

Further Reading

This post was all about DMDM Hydantoin

Thank you for reading my post on DMDM Hydantoin. If you have had any negative experiences from using products containing this antimicrobial preservative please leave a comment below. DMDM hydantoin is an important ingredient because prevents microbial growth and helps protect products from spoiling.

John Randall

Friday 3rd of September 2021

I have experienced an extreme side effect from using Suave shampoo. My entire face and scalp turns a bright red that lasts for several days. While there is no pain invovled (thank goodness), it is embarrising to watch the reaction of people that first see my face.This has occurred the last two times I used an almost empty bottle of that shampoo - both within in the last month or so. This problem did NOT occur any time in the past as I used the majority of the bottle quite some time ago.

I now realize that the problem is probably due to DMDM Hydantoin. I have bought a new bottle of the same product and find that it now does not show DMDM Hydantoin as an ingredient. I hope that when I use the material in the new bottle, I won't have the same outcome.

If I am do have the same problem, I will let you know.

I just notices that you are affiliated with Given their predatory practices, I am no longer buying anything from them. I suggest that you re-think your association with Amazon. They have some very nasty policies. Obviously, I am assuming that the UK operation is as corrupted as the USA operation - but do not know that for a fact.

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