18 Causes of Hair Loss—And What You Can Do About It

Thinning hair, shedding hair, and hair loss affect both men and women. And it's no more or less demoralizing for either, according to a study published in 2022 in the Journal of Cosmetic Dermatology.

But here's the thing: There are different reasons behind hair loss—causes range from a vitamin deficiency to taking too much vitamin A to chronic underlying health conditions.

Luckily, there are many ways to treat hair loss, depending on the cause. Here are some common (and not-so-common reasons) why you might be seeing less hair on your head—and what you can do about it.

Too Much Vitamin A

Deficiencies of vitamins can cause hair loss (e.g., vitamins D & B7, biotin). However, overdoing vitamin A-containing supplements or medications can also trigger hair loss, according to the American Academy of Dermatology. 

The Food and Drug Administration recommends 5,000 International Units (IU) of vitamin A per day for adults and children over the age of four years. Supplements can contain 2,500 to 10,000 IU. So, any more than that, you could risk some strands falling out.

The good news is too much vitamin A is also a reversible cause of hair loss. Once the excess vitamin A is halted, hair should start growing normally again.

Stress or Illness

Stress or illness can cause hair loss. It's a process known as telogen effluvium, or the excessive shedding of hair induced by stress, Michelle Henry, MD, a dermatologist based in New York, previously told Health.

"Our bodies perceive mental stress the same way they perceive physical stress. And any dramatic stressor on the body can cause hair growth to become arrested," explained Dr. Henry. "And when hair growth is arrested, it sheds." 

Specifically, when stressed, the body releases the hormone cortisol, which can affect the hair follicle and result in shedding or hair loss. That shedding typically occurs at least three months following a stressful event, Angelo Landriscina, MD, a Washington, DC-based dermatologist, previously told Health.

While limiting stress can help prevent hair loss—that's not always easy. If you experience hair loss, check in with your healthcare provider. According to a review published in 2017 in the journal American Family Physician, if your healthcare provider determines that your hair loss is stress-related, they may recommend a treatment called minoxidil. That's a vasodilator that improves circulation around the hair bulb at the base of the hair follicle to help grow hair back that you've lost. 

Also important: Having patience and allowing time for hair regrowth.

Pregnancy

Pregnancy is one type of physical stress that can cause hair loss (that and hormones). Pregnancy-related hair loss is seen more commonly after your baby has been delivered rather than during pregnancy. 

"Giving birth is pretty traumatic," explained Marc Glashofer MD, a dermatologist who sees patients at Schweiger Dermatology Group.

If you experience hair loss after pregnancy, rest assured that your hair will grow back in a couple of months. 

"It's a normal thing, and it will work its way out," said Dr. Glashofer.

Protein Deficiency

According to the American Academy of Dermatology (AAD), having too little protein in your diet can lead to unwanted hair loss. It may also be why, anecdotally speaking, people who are dieting may report some hair loss.

You can easily add more protein to your diet by incorporating more eggs, chicken, beans, and yogurt into your daily meal plan.

Female and Male–Pattern Baldness

You might already know about male–pattern baldness. It's a type of hair loss caused by a combination of genes and male sex hormones that usually makes the hair recede at the temples, leaving an M–shaped hairline.

But there's also hormone-related hair loss for females—or female–pattern baldness—according to the National Institute of Health (NIH). That hair loss occurs when the hair follicle shrinks so much over time that it doesn't grow new hair. 

The symptoms of female–pattern baldness include widening the center hair part and, sometimes, coarser hair on the face. Often, that type of hair loss can be genetic.

"If you come from a family where women started to have hair loss at a certain age, then you might be more prone to it," said Dr. Glashofer. 

Rogaine (minoxidil) is the only FDA–approved treatment for female– and male–pattern hair loss. Rogaine is available over-the-counter (OTC) but talk to your healthcare provider before you use it. Like all medications, Rogaine can cause unwanted side effects.

Still, if that doesn't work, your healthcare provider may prescribe oral medications, such as Propecia (finasteride), which can halt hair loss. They may even cause some to grow, And surgery to transplant or graft hair is also an option.

Changing Hormones

In a study published in 2022 in the Journal of Cosmetic Dermatology, researchers explained that stopping or starting birth control pills and enduring menopause may lead to hair loss. That's because of the change in the hormonal balance that occurs during those events. 

"The androgen (male hormone) receptors on the scalp become activated," explained Mark Hammonds, MD, a dermatologist with Scott & White Clinic in Round Rock, Texas. "The hair follicles will miniaturize, and then you start to lose more hair," Dr. Hammonds said.

Talk to your healthcare provider about other birth control types if a new Rx is a problem. Dr. Hammonds said that stopping oral contraceptives can also sometimes cause hair loss, but this is temporary.

Low Iron Levels

The AAD lists iron deficiency as a potential cause of unwanted hair loss. And according to the National Heart, Lung, and Blood Institute (NHLBI), iron-deficiency anemia occurs when you don't have enough iron in your body. The symptoms include fatigue, tiredness, shortness of breath, or chest pain. 

To help remedy an iron deficiency, your healthcare provider might suggest iron supplements or other healthy lifestyle choices. Those may include increasing your intake of both iron- and vitamin-C-rich foods.

A Thyroid Condition

Thyroid conditions—like hyperthyroidism and hypothyroidism—can cause various hair issues.

According to the AAD, those include: thinning or missing eyebrows (mainly on the outer edge of the eyebrow), soft and delicate hair with lots of shedding, thinning hair, and less hair on other body parts.

Suppose you have experienced hair loss with a thyroid issue. In that case, the best bet is to speak with your healthcare provider about treatment possibilities. Usually, treating the underlying cause first is essential to treating any other associated issues.

Alopecia Areata

Alopecia areata, a common autoimmune skin disease, causes hair loss on the scalp and other places on the body, according to the National Alopecia Areata Foundation (NAAF).

The NAAF says that the disease affects about 6.8 million people in the United States. People of any age, sex, or ethnic group can develop the condition.

There are different types of alopecia areata—and all will result in some form of hair loss. But there's no way to predict how much or if it will return.

There are various treatment options for alopecia areata, per the NAAF. Those include topical treatments, along with oral or injectable medications.

Lupus

Lupus is an autoimmune disease in which the immune system attacks the body's healthy cells and tissues. According to the National Library of Medicine, it affects the joints, skin, kidneys, heart, lungs, blood vessels, and brain.

Hair loss is a common side effect of both lupus and the medications used to treat lupus, per the Lupus Foundation of America (LFA). Sometimes, with lupus, scarring on the scalp during hair loss may inhibit hair from growing back. Still, when treatment is complete, hair loss due to medication may stop (and the hair may grow back).

The LFA said that if you are experiencing hair loss, it's always wise to speak with your healthcare provider before you try any treatments (like Rogaine) on your own.

Weight Loss

According to the AAD, weight loss can result in thinning hair. That can happen even if the weight loss is ultimately good for you. Weight loss can stress your body unnecessarily or may result in vitamin or mineral deficiencies.

Loss of hair and noticeable weight loss may also be symptoms of an eating disorder such as anorexia or bulimia.

That type of hair loss, too, will stop after weight normalizes and the body's nutritional needs are restored. 

"Sudden weight loss seems to shock the system, and you'll have a six-month period of hair loss, and then it corrects itself," explained Dr. Hammonds.

Chemotherapy

Unfortunately, some of the drugs used to beat back cancer can also cause your hair to fall out. 

"Chemotherapy is like a nuclear bomb," said Dr. Glashofer. "It destroys rapidly dividing cells. That means cancer cells, but also rapidly dividing cells like hair." 

According to an article published in 2022 in the journal Supportive Care in Cancer, your hair will grow back once chemotherapy stops.

However, often it will come back with a different texture (perhaps curly when before it was straight) or a different color. Researchers are working on more targeted drugs to treat cancer that could bypass this and other side effects.

Polycystic Ovary Syndrome

According to an article published in 2022 in the Journal of Cosmetic Dermatology, polycystic ovary syndrome (PCOS) is a condition that causes a hormone imbalance. An access amount of the hormone androgen, a male sex hormone, can lead to ovarian cysts, weight gain, a higher risk of diabetes, changes in the menstrual cycle, infertility, and hair thinning. 

Because androgen is overrepresented in cases of PCOS, those people may also experience more hair on the face and body.

Treating PCOS can correct the hormone imbalance and help reverse some of these changes. Treatments include diet, exercise, and potentially birth control pills, as well as specific treatment to address infertility or diabetes risk.

Medication

According to an article published in 2006 in the journal Current Drug Safety, many medication classes may promote hair loss. Certain blood thinners and blood-pressure drugs, known as beta-blockers, are more common among them. 

Other drugs that might cause hair loss include methotrexate (used to treat rheumatic conditions and some skin conditions); lithium (for bipolar disorder); nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen; and antidepressants.

If your healthcare provider determines that one or more of your medications is causing hair loss, talk with them about lowering the dose or switching to another medicine.

Over-Styling

According to the AAD, vigorous styling and hair treatments can cause your hair to fall out. 

Examples of extreme styling include tight braids, hair weaves, corn rows, chemical relaxers to straighten your hair, hot-oil treatments, or any kind of harsh chemical or high heat. Because those practices affect the hair root, your hair might not grow back.

In addition to avoiding those styles and treatments, the AAD recommends using conditioner after shampooing and letting your hair air dry. Additionally, limit the time the curling iron comes in contact with your hair, and use heat-driven products no more than once a week.

Compulsively Hair Pulling

Trichotillomania, an "impulse control disorder," causes people to pull their hair out compulsively. The condition often begins before age 17 and is four times as common in women as in men.

"It's sort of like a tic. The person is constantly playing and pulling their hair," explained Dr. Glashofer. 

Unfortunately, that constant playing and pulling can strip your head of its hair, according to an article published in 2021 in the journal Psychiatry Online. 

Some antidepressants may be effective as a treatment, and behavioral modification therapy is another option.

Age

It's not uncommon to see hair loss or thinning of the hair in women as they enter their 50s and 60s, said Dr. Glashofer.

Experts don't recommend that this condition be treated, said Dr. Hammonds. That leaves women with cosmetic approaches such as scarves, wigs, and hair styled to cover up thin spots. 

That said, there are plenty of tricks to prevent hair breakage and ways to keep your hair looking shiny and healthy in your 50s and beyond, such as moisturizers and avoiding over-styling.

Anabolic Steroids

Anabolic steroids can have the same impact on the body as PCOS because the mechanism is the same, explained Dr. Hammonds. 

If you take anabolic steroids—the type abused by some athletes to bulk up muscle—you could lose your hair. Hair loss should improve after going off the drug.

Our hair is part of our identity, allowing us to outwardly showcase our personalities. So, it's no wonder that the thinning or shedding of your hair can be quite unnerving and disheartening.

If you are experiencing hair loss, consult your healthcare provider to determine the cause. Most often, treatments for reducing hair loss begin by tackling the underlying problem.