5 Shampoos That Have Been Linked to Hair Loss

Finding more hair than usual in the shower drain is unsettling. Hormones, stress, and diet usually get the blame, but some people start to wonder about the bottle on the shelf.

Over the past decade, several popular shampoo and cleansing brands have faced lawsuits and thousands of consumer complaints claiming their products caused hair loss or scalp irritation. Below are five of the best-known cases, what they claimed, and how to protect your hair.

An important note: these are allegations. In most cases, a link between the product and hair loss has not been proven in court, and the companies have denied the claims.

The 5 shampoos

1. WEN by Chaz Dean Cleansing Conditioners

WEN became famous through late-night infomercials. Its no-lather cleansing conditioners were sold as a gentler alternative to shampoo. Before the lawsuit, the FDA started receiving complaints from buyers who reported hair loss and scalp irritation.

After more than 100 complaints came in over a short period, a class action followed. WEN agreed to a $26 million settlement in 2016 without admitting wrongdoing.

2. DevaCurl

DevaCurl was a favorite in the curly-hair community. In 2020, four class actions were filed against the brand. Some plaintiffs said the hair loss was severe enough that they had to cut their hair short or wear wigs.

The company disputed the claims. It pointed out that hair loss can also come from pregnancy, weight loss, or stress.

3. TRESemmé Keratin Smooth

A nationwide class action against Unilever claimed some TRESemmé products caused hair loss and scalp irritation. The suit focused on DMDM hydantoin, a preservative that releases small amounts of formaldehyde. It named TRESemmé Keratin Hair Smoothing Shampoo and Keratin Smooth Color Shampoo.

TRESemmé said DMDM hydantoin is widely used across the beauty industry and has been confirmed safe by health authorities.

4. OGX (Johnson & Johnson)

Starting in 2021, lawsuits claimed DMDM hydantoin in certain OGX shampoos and conditioners caused hair loss and scalp irritation. In September 2021, Johnson & Johnson said it would stop making OGX products containing the ingredient.

5. Suave Professionals Keratin Infusion

This is another Unilever line, and it was caught up in the same wave of DMDM hydantoin lawsuits. Critics noted that it was marketed as nourishing and even as reducing hair loss, while containing the same formaldehyde-releasing preservative.

What about Nigeria?

No Nigerian court case or NAFDAC alert has tied a specific shampoo to hair loss so far. Many of the international brands above are imported into Nigeria, though. NAFDAC has also flagged several hair-product risks that Nigerian readers should know about.

Formaldehyde in hair smoothing products

In April 2021, NAFDAC issued Public Alert No. 006/2021 warning against hair smoothing and straightening products that contain formaldehyde. The agency said most of these products release formaldehyde gas, a known human carcinogen, while hair is being straightened. It advised against using them at home and said they should only be applied by trained professionals in a salon, with gloves, eye protection, and good ventilation. (The Guardian Nigeria)

Placentyne Hair Lotion

In 2022, NAFDAC banned Placentyne Hair Lotion (12 ampoules x 10ml, by Linea Italiana di Benazzi Anna & SAS) after it was banned in Europe. The concern was MCI and MI, two preservatives linked to allergic reactions. NAFDAC told the public to stop using the product and hand it over to the nearest NAFDAC office. (Leadership)

Fake and refilled hair and beauty products

Counterfeits may be the biggest risk for Nigerian shoppers. In September 2025, NAFDAC said it had intercepted fake cosmetics worth over ₦500 million in Lagos markets. Counterfeiters were importing empty containers of real brands and refilling them with fake products. (AllAfrica) A fake shampoo with unknown ingredients is far more likely to irritate your scalp than the genuine product.

Tips for Nigerian shoppers

Buy from trusted supermarkets, pharmacies, and official brand stores rather than open-market stalls or unknown online sellers.
Check for a NAFDAC registration number on the label, and be wary of prices that seem too good to be true.
Look for signs of tampering, such as broken seals, smudged labels, or an unusual smell or texture.
Report a bad reaction to NAFDAC through PRASCOR on 20543 or 0800-1-NAFDAC (0800-1-623322), toll-free, or at pharmacovigilance@nafdac.gov.ng.

The ingredient behind most of the claims

Three of the five cases center on DMDM hydantoin. It is a preservative that slowly releases tiny amounts of formaldehyde to keep products from growing bacteria and mold.

The scientific evidence that it causes hair loss at the low levels used in shampoo is weak. Its better-documented risk is contact allergy. People who are sensitive to formaldehyde can develop itching, redness, and dermatitis, and a badly inflamed scalp can shed more hair.

Other formaldehyde-releasing preservatives to look for on labels:

Quaternium-15
Imidazolidinyl urea
Diazolidinyl urea
Bronopol (2-bromo-2-nitropropane-1,3-diol)

Your shampoo may not be the culprit

Hair loss has many causes, and some of them can happen around the same time as a change of shampoo by coincidence. Common causes include:

Stress or illness. Telogen effluvium is a temporary shedding that often starts two to three months after a stressful event, surgery, or high fever.
Hormonal changes. Pregnancy, giving birth, menopause, and thyroid problems can all trigger shedding.
Genetics. Male- and female-pattern hair loss is the most common type.
Nutrition. Low iron, rapid weight loss, or very restrictive diets can thin hair.
Styling damage. Tight hairstyles, heat tools, bleaching, and chemical straightening can cause breakage.

How to protect your hair

Read the ingredient list. If your scalp is sensitive, skip products with the formaldehyde releasers listed above.
Patch test new products. Apply a little behind your ear or on your inner arm and wait 48 hours before using it on your scalp.
Stop at the first warning sign. Burning, itching, redness, or sudden shedding after switching products is a reason to stop using it.
Keep a record. Note when you started a product and when symptoms began, and keep the bottle. This helps your doctor, and any claim you might make later.
See a dermatologist if shedding lasts. Persistent hair loss usually has a cause that can be found and treated, and early treatment works best.

The bottom line

A few well-known shampoo brands have faced serious hair loss allegations, and one paid a large settlement. Still, most shampoos are safe for most people, and the science linking common preservatives to hair loss is limited. Pay attention to how your scalp reacts, read labels, and talk to a dermatologist if your hair loss doesn’t stop.

This article is for general information only and is not medical or legal advice. The products listed were named in lawsuits or consumer complaints. Inclusion does not mean a product has been proven to cause hair loss.