9 Surprising Things That Can Cause Hair Loss, Experts Say

1 | Vitamin deficiencies

If you’ve noticed unexplained hair loss, experts say you may need to turn your attention to your diet. That’s because vitamin deficiencies are a surprising—yet somewhat common—cause for hair loss or hair thinning.

"A balanced diet is crucial for healthy hair growth," explains dermatologist Zein Obagi, MD. "Certain nutritional deficiencies, such as inadequate iron, zinc, biotin, or protein intake, can impact the hair follicles' ability to produce new hair strands. Incorporating a well-rounded diet and considering targeted supplementation, when necessary, can help promote hair health and reduce the risk of hair loss," he tells Best Life.

Though most people should be able to get the necessary vitamins and minerals through a balanced diet, restrictive eating plans can compromise your intake, says Yoram Harth, MD, a board certified dermatologist and the medical director of MDhair. “Extreme or crash dieting can deprive the body of essential nutrients, including those crucial for maintaining healthy hair growth,” he warns.

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2 | Heavy metal poisoning

In rare cases, hair loss can indicate a serious underlying condition, says Kelly Johnson-Arbor, MD, a medical toxicology physician and interim executive director at National Capital Poison Center. In particular, it can sometimes suggest heavy metal poisoning, or exposure to toxic heavy metals.

Johnson-Arbor tells Best Life that thallium and arsenic poisoning are the two types most likely to cause hair loss. “In the human body, these heavy metals interfere with normal cellular metabolism and function, disrupting hair growth and other organ functions,” she explains. “Hair loss associated with heavy metal poisoning is often diffuse in nature and is typically accompanied by other signs and symptoms, including confusion, numbness and tingling in the hands and feet, and gastrointestinal disturbances,” the toxicologist adds.

3 | Dermal filler injections

Dermal filler injections, used to treat wrinkles and create a more youthful appearance, can also cause hair loss, Johnson-Arbor warns.

“When fillers are injected into the subcutaneous tissues, the small volume of fluid injected can cause pressure on blood vessels, blocking blood flow to nearby hair follicles,” she explains. “This is most commonly noted after filler injection into the forehead area. This type of hair loss frequently resolves over a period of several months."

Hyaluronic acid and botulinum toxin (Botox) injections are two popular types that can lead to hair loss in rare instances. However, Johnson-Arbor notes that Botox is also sometimes used to treat hair loss, “as it relaxes the scalp muscles and leads to potentially improved blood flow to the scalp.”

4 | Emotional or physical stress

Obagi points out that emotional and physical stress can also disrupt the normal hair growth cycle, resulting in hair loss or hair thinning. “When a person experiences a significant life event, undergoes emotional distress, or endures physical trauma, their body may divert energy away from hair growth, leading to temporary hair loss or telogen effluvium,” he explains. However, the dermatologist notes that this type of hair loss is often reversible once the stress is managed effectively.

5 | Autoimmune conditions

If you notice unexplained hair loss, it’s important to discuss your symptoms with your doctor. They may want to screen you for certain autoimmune conditions, among other things.

“Autoimmune conditions, such as alopecia areata, can cause hair loss by mistakenly attacking the hair follicles,” says Obagi. “This results in the interruption of the hair growth cycle and subsequent hair loss. Treating the underlying autoimmune condition and seeking appropriate medical intervention can help manage hair loss in such cases,” he adds.

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6 | Medication side effects

Your medication could also be to blame for your hair loss, Obagi says. If you suspect medication as the cause of hair loss, he recommends consulting with a healthcare professional to explore alternative options or mitigate the effects.

“Hair loss can be an unintended side effect of certain medications, such as chemotherapy drugs, antidepressants, beta-blockers, or hormonal treatments,” says Obagi. “These medications can disrupt the hair growth cycle or induce telogen effluvium."

7 | Certain hairstyles

How you style your hair can also determine whether you get to keep it, experts say. “Certain hairstyles that exert excessive tension on the hair follicles, such as tight ponytails, braids, or extensions, can lead to traction alopecia,” explains Obagi. “The constant pulling can weaken the hair strands, causing them to break or fall out,” he adds. By opting for looser hairstyles and avoiding excessive heat, you can help prevent this form of hair loss, the dermatologist says.

8 | Dry shampoos and chemical treatments

Certain hair products may also contribute to hair loss, experts warn. In particular, some dermatologists have warned against the frequent use of dry shampoos, since these can lead to a buildup of bacteria on the scalp, causing inflammation. Some people will go on to develop pimples or cysts on their scalps in those inflamed areas, eventually resulting in dry areas and scabs. This can cause the hair to fall out in patches, dermatologists tell Insider.

Chemical treatments, including chemical hair straighteners, have also been found to cause hair loss. In fact, a 2022 study found that besides their association with hair loss and scalp inflammation, these types of treatments were also linked to increased incidence of eczema, pain, burns, changes in hair color, and more.

9 | Hormonal changes

Finally, hormonal fluctuations can play a significant role in hair loss, says Harth. “Pregnancy, childbirth, menopause, and conditions like polycystic ovary syndrome (PCOS) can cause hormonal imbalances that impact the hair growth cycle,” the dermatologist notes. “These changes can lead to temporary hair loss or even permanent hair thinning."

Speaking with a healthcare provider specializing in hormonal health can help address the underlying causes and manage any associated hair changes.

Best Life offers the most up-to-date information from top experts, new research, and health agencies, but our content is not meant to be a substitute for professional guidance. When it comes to the medication you're taking or any other health questions you have, always consult your healthcare provider directly.