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

It's true that men are more likely to lose their hair than women, but thinning hair and hair loss actually affects both sexes—and it's no more or less demoralizing for either. But here's the thing: There's no one reason behind hair loss—causes can range from the simple and temporary (like a vitamin deficiency) to the more complex, like an underlying health condition.

Luckily, there are also many ways to treat hair loss in both women and men (cause-dependent, of course) 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.

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Pregnancy is one example of the 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 actually during pregnancy. “Giving birth is pretty traumatic,” says Dr. Glashofer.

If you do 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,” Dr. Glashofer says.

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• Overdoing vitamin A-containing supplements or medications can trigger hair loss, according to the American Academy of Dermatology. Just FYI: The Daily Value for vitamin A is 5,000 International Units (IU) per day for adults and kids over age 4; supplements can contain 2,500 to 10,000 IU. So any more than that and you could risk some strands falling out.
• The good news: This is also a reversible cause of hair loss, and once the excess vitamin A is halted, hair should start growing normally again.

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

But hormone-related hairloss for females—or female–pattern baldness—is also a thing, according to the US National Institute of Health. This type of hair loss occurs (in both men and women) when the hair follicle shrinks so much over time that it doesn't grow new hair. In women, the symptoms of female–pattern baldness includes a widening of the center hair part, and, sometimes, coarser hair on the face.

The only FDA–approved treatment for female– and male–pattern hair is minoxidil (Rogaine; $45 on amazon.com), but if that doesn't work, your doctor may prescribe oral medications such as finasteride (Propecia) that can halt hair loss or even cause some to grow; surgery to transplant or graft hair is also an option.

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“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,” says Dr. Glashofer. Unlike men, women don't tend to have a receding hairline, instead their part may widen and they may have noticeable thinning of hair. This is also known as female–pattern baldness.

Women may benefit from minoxidil (Rogaine) to help grow hair, or at least, maintain the hair you have, Dr. Glashofer says. Rogaine is available over-the-counter and is approved for women with this type of hair loss.

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• Sudden weight loss is a form of physical trauma that can result in thinning hair. This could happen even if the weight loss is ultimately good for you. It’s possible that the weight loss itself put unnecessary stress your body, or that not eating right can resulted in vitamin or mineral deficiencies. Loss of hair along with noticeable weight loss may also be a sign of an eating disorder such as anorexia or bulimia.
• This type of hair loss, too, will correct itself once after a while. "Sudden weight loss seems to shock the system and you’ll have a six-month period of hair loss and then it corrects itself,” says Dr. Hammonds.

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• Some of the drugs used to beat back cancer unfortunately can also cause your hair to fall out. “Chemotherapy is like a nuclear bomb,” says Dr. Glashofer. “It destroys rapidly dividing cells. That means cancer cells, but also rapidly dividing cells like hair.”
• Once chemotherapy is stopped, your hair will grow back although 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, ones that would bypass this and other side effects. Luckily, there are a few ways to deal with hair loss during chemotherapy, like shaving it or covering it up with a scarf.

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• Polycystic ovary syndrome (PCOS) is another imbalance in male and female sex hormones. An excess of androgens can lead to ovarian cysts, weight gain, a higher risk of diabetes, changes in your menstrual period, infertility, as well as hair thinning. Because male hormones are overrepresented in PCOS, women 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.

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• Certain other classes of medication may promote hair loss. More common among them are certain blood thinners and the blood-pressure drugs known as beta-blockers. 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) including ibuprofen, and possibly antidepressants.
• If your doctor determines that one or more of your medications is causing hair loss, talk with him or her about either lowering the dose or switching to another medicine.

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Vigorous styling and hair treatments over the years can cause your hair to fall out. Examples of extreme styling include tight braids, hair weaves or corn rows as well as chemical relaxers to straighten your hair, hot-oil treatments or any kind of harsh chemical or high heat. Because these practices can actually affect the hair root, your hair might not grow back.

In addition to avoiding these styles and treatments, the American Academy of Dermatology recommends using conditioner after every shampoo, letting your hair air dry, limiting the amount of time the curling iron comes in contact with your hair and using heat-driven products no more than once a week.

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Trichotillomania, classified as an “impulse control disorder,” causes people to compulsively pull their hair out. “It’s sort of like a tic, the person is constantly playing and pulling their hair,” says Dr. Glashofer says. Unfortunately, this constant playing and pulling can actually strip your head of its natural protection: hair. Trichotillomania often begins before the age of 17 and is four times as common in women as in men.

Some antidepressants may be effective, but behavioral modification therapy is another option.

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It’s not uncommon to see hair loss or thinning of the hair in women as they enter their 50s and 60s, says Dr. Glashofer. Experts aren’t sure why this happens.

Experts don't recommend that this condition be treated, says Dr. Hammonds. That leaves women with cosmetic approaches such as scarves, wigs and hair styled so as to cover up thin spots. That said, there are also plenty of tricks to prevent hair breakage and ways to keep your hair looking shiny and healthy in your 50s and above.

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If you take anabolic steroids—the type abused by some athletes to bulk up muscle—you could lose your hair, according to the American Academy of Dermatology. Anabolic steroids can have the same impact on the body as polycystic ovary disease (PCOS), as the mechanism is the same, says Dr. Hammonds.

Hair loss should improve after going off the drug.

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