Chemicals That Cause Hair Loss

While many hair care products on the market are safe, there are still some chemicals that can cause hair loss lurking in certain shampoos, conditioners, and styling products. Other household items can also contain hair-harming chemicals or other harmful toxins. 

But, there’s no need to panic about your daily routine or the products stashed under your sink or around your home. 

In this guide, we highlight specific chemicals known to contribute to hair loss. We also provide some helpful tips to help you steer clear of chemical-related hair issues. Plus, we explore other factors that could be behind your hair loss, including hormones, genetics, stress, and more.

First, we should mention that the Food and Drug Administration (FDA) approves most hair products sold in stores and online, and that these items are generally safe to use and unlikely to cause hair loss.

There are, however, a few ingredients in some hair care products that can potentially harm your scalp and hair follicles, especially when used excessively or incorrectly. Long-term exposure to certain toxins from common household items or occupational exposure can also trigger hair loss. 

Keep reading to learn about the toxins that cause hair loss and how you can minimize the damage from each potential source.

1. Formaldehyde

Formaldehyde is used in many household products, such as glues, adhesives, permanent-press fabrics, and certain insulation materials. Cosmetics manufacturers also use it as a preservative. 

Unfortunately, formaldehyde is also a carcinogen that can cause irritation, allergic dermatitis and skin sensitivity. Even when formaldehyde isn’t an ingredient in a product, substances that release formaldehyde might be present in some shampoos or keratin-based hair-smoothing treatments.

While there isn’t extensive evidence supporting a link between formaldehyde and hair loss, there has been some research to suggest the chemical may be harmful to hair and skin. 

A 2022 study out of Brazil found that hair straighteners or relaxers containing formaldehyde and other chemicals were associated with:

• Scalp irritation

• Inflammation

• Hair loss

Formaldehyde-related irritation can cause you to scratch your scalp, potentially resulting in hair follicle damage. 

To avoid exposing your hair to formaldehyde, ask your stylist about the ingredients in any hair smoothing or straightening treatments they use. You can also check the labels on your personal care products for formaldehyde and related ingredients, such as formalin and methylene glycol.

2. Hair Dye

While personal hair dye use is a fun way to switch up your look, using color or bleach weakens your hair, causing it to become more prone to breakage.

The ingredients in hair dyes — like ammonia and hydrogen peroxide — weaken the hair shaft by damaging the protein within, leading to shedding and breakage of existing hairs in the telogen stage (the rest stage of the hair growth cycle). 

A 2023 report in Frontiers in Medicine suggests that just about any chemical process involved with hair dyes or perms can damage the hair shaft and affect the hair growth process.

To avoid breakage and loss from personal hair dye use, try to add time between touch-ups — every eight to 10 weeks or longer. You can also avoid hair dye use in the winter when the air is dryer.

Be sure to carefully follow the instructions provided if you’re dyeing your hair yourself. Otherwise, get your hair bleached and colored by an experienced professional.

3. Medications

Some prescription drugs, including chemotherapy medications like antimetabolites, mitotic inhibitors, and alkylating agents, can cause a type of drug-induced hair loss called anagen effluvium.

This type of hair loss starts when hairs in the anagen phase of the hair growth cycle suffer from chemical toxicity or inflammation, preventing them from growing properly, usually within 14 days of medical treatment.

Unlike male pattern baldness, loss of hair from anagen effluvium is usually only temporary. It’s common for affected hair to grow back once it’s no longer exposed to medications that produce this type of hair shedding.

4. Heavy Metals

Research has found a link between long-term exposure to heavy metals and alopecia — a form of hair loss.

A review of 47 articles and studies on alopecia found that heavy metals like mercury and thallium were the top toxins responsible for anagen effluvium. 

Other heavy metals linked to anagen effluvium include: 

• Boron

• Thallium

• Cadmium

• Copper

• Bismuth

Heavy metal poisoning can happen from occupational exposure if your work involves manufacturing certain electronics like semiconductor materials and alloys.

You should look out for these metals if you work in an industrial environment. But, they don’t show up in hair care products.

5. Arsenic Poisoning

Another toxin that causes hair loss is chronic arsenicosis — or prolonged exposure to toxic levels of arsenic, a naturally-occurring metalloid found in soil, water, and seafood.

The World Health Organization (WHO) estimates 140 million people worldwide use water containing potentially unsafe levels of arsenic.

According to the Centers for Disease Control and Prevention (CDC), workers in certain industries may also be susceptible to chronic arsenicosis, including glass manufacturing, agriculture and construction.

However, the risk of arsenic poisoning from environmental causes is rare in the U.S. The Environmental Protection Agency (EPA) sets a limit of 0.01 parts per million (ppm) for arsenic in drinking water.

Toxins aren’t the only cause of hair loss. Male pattern baldness (AKA androgenetic alopecia) results from a combination of genetic factors and your body’s production of male sex hormones, or androgens.

Specifically, hair loss from male pattern baldness happens due to a genetic sensitivity to the hormone dihydrotestosterone, or DHT, a byproduct of testosterone.

DHT plays a crucial role in puberty and is responsible for facial, pubic and body hair growth. It can also cause your hair follicles to gradually become weaker and, in some cases, stop producing new hairs as you get older.

Our complete guide on DHT and its effects on male hair loss goes into more detail on this process.

While male pattern baldness is the most common type of hereditary hair loss, there are other causes of hair loss.

Alopecia Areata

Alopecia areata is an immune system disease that causes hair loss. It’s thought to be a result of changes to certain genes in the hair and skin. Hair typically falls out in round patches, leaving small bald spots the size of coins.

Telogen Effluvium

Another type of hair loss, telogen effluvium, occurs after a stressful or traumatic event. These stressful events might include illnesses, metabolic stress, trauma, infection, surgery, hormonal changes, nutritional deficiencies, or the use of certain medications.

Traction Alopecia

If your hair is long enough to tie back, traction alopecia can occur when you frequently choose hairstyles that pull on the roots of the hair. Tight hairstyles that put repetitive tension on the hair are the most common reason for this type of hair loss.

Tinea Capitis

Tinea capitis, or scalp ringworm, is a fungal infection that causes the loss of scalp hair. When the fungi that cause the infection penetrate the root sheath of the hair follicle, they may cause temporary hair loss. In some cases, tinea capitis can result in irreversible damage due to scarring.

While the majority of substances in over-the-counter (OTC) hair products won’t increase hair shedding, there are some chemicals that cause hair loss. 

Here’s how you can try to prevent it.

• Take breaks between dye jobs. Try not to go overboard with personal hair dyeing to prevent your hair from getting weak and breaking. You can also use conditioner after every time you color to moisturize your hair, which can improve its appearance and texture.

• Avoid the use of keratin straightening products or other hair care products that use formaldehyde. This ingredient may increase irritation and hair thinning.

• Check hair care product labels before you buy them. Although uncommon, some ingredients in consumer hair products may cause allergic reactions, irritation, and even hair loss.

• Read the ingredients list on household cleaners and other products. If anything raises a red flag, do some research and look for products containing fewer toxins.

The best way to avoid damaging your hair is to use research-backed hair products, like those in our range of hair products for men. You can also learn more effective hair care tips in our roundup of 18 men’s hair care tips.

If you’re starting to lose hair and think exposure to toxins is the culprit, you can learn more about your options to avoid further hair loss and stimulate new growth in our guide to male pattern baldness.

We also offer common prescription hair loss medications online, such as finasteride, minoxidil foam and minoxidil liquid, following a consultation with a licensed healthcare provider who’ll determine if a prescription is appropriate.