What Causes Hair Loss (and What to Do If You Think You’re Losing Yours)

Everyone leaves a little hair in their drain, but what if what you’re seeing is something more? Feeling like you’re losing hair can be a very scary thing. We talked to Dr. Lynne Goldberg, Director of Boston Medical Center’s Hair Clinic, Professor of Dermatology and Pathology & Laboratory Medicine at Boston University, and a member of our medical advisory board, about the primary causes of hair loss and what to do if you think it’s happening to you. Read on for her expert advice.

What are the common reasons people experience hair loss?
The causes of hair loss, or alopecia, are numerous, and range from genetic susceptibility to auto-immune disease. Some causes of hair loss are reversible, and others cause irreparable scarring. Some cause patchy hair loss, while others more evenly affect the top of the scalp or the entire scalp. The most common type of hair loss that I see in women is female pattern hair loss. This results in hair loss on the temples and the top of the head. The incidence of this inherited hair loss increases with age, but can start as young as age 12 or 13.

There are causes of hair loss related to diet, nutrition, and endocrine disorders such as thyroid disease. Alopecia areata is an autoimmune disease that results in patchy hair loss. There are psychological reasons for hair loss as well, like extreme stress. However,  when we talk about stress and psychological events causing hair loss, it’s important to note that it’s not the daily stress most of us experience. It’s something bigger, like the emotional devastation of the death of a loved one or the shock to the body by a major car accident. Major emotional and physical events can affect the normal cycle of hair, in which hair grows for a period of years and then falls out in a period of months, only to regrow again. A major stressful event causes this cycle to synchronize, and hair falls out all at once. Traumatic events take about three months to manifest in the hair, so you wouldn’t experience this type of hair loss right away. Pregnancy, dramatic weight loss, and a drastic diet change are all examples of events that can cause hair to fall out. The good news is that hair loss caused by stress typically resolves once the stress passes.

How often does inherited hair loss happen?
By the age of 50, it is estimated that around 40 percent of women have female pattern hair loss. It’s that common. But not all women seek care for this problem.

Some hair loss is normal, right?
It’s normal to lose one hundred hair strands in a day. That includes brushing, shampooing, wind, and the like. I think most people have a general sense of what is normal for them. It’s very variable—no two people are alike.

People are all born with a certain number of hair follicles and that is what they will have for life—you don’t produce more hair follicles after birth. Because each hair follicle produces a hair shaft in a cyclic fashion – the hair shaft grows, then it falls out, then it grows, then it falls out, etc., it is normal for hair shafts to be shed daily.

You mentioned pregnancy can cause hair loss. Talk us through what happens.
During pregnancy the growth cycle actually lengthens, so you lose hair after pregnancy when normally you would have lost it earlier.

What’s the difference between baldness and thinning?
Thinning of hair is a descriptive term—not a diagnosis. The term baldness typically refers to male pattern hair loss, but women can experience “baldness” as well.

Is there any truth to the belief that baldness is inherited from your mother’s side?
No. Male and female pattern hair loss can be inherited from both sides of the family.

Can cosmetic products cause hair loss?
I haven’t seen that in my years of practice. What is common is people who come in with breakage and fragile hair from practices like too frequent bleaching, for example. But that is more about their habits than the products they are using.

The reason I have a hard time attributing any kind of hair loss to hair products is that hair loss occurs under the skin at the level of the hair follicle bulb. I can’t imagine why something you are applying to the hair’s shaft would cause a change underneath in the root of the follicle. It can cause breakage of the hair shaft on the surface, sure, but not hair loss. There’s just not a scientific basis for loss of the hair follicle from a product designed and tested for use on the hair shaft.

In some high profile instances of people blaming a product for their hair loss, the loss was patchy. That’s a common finding in alopecia areata, an  auto-immune disease. But if the product were causing hair loss, it would probably affect all of the hair equally, because you are applying the product all over—not in just one concentrated patch. Think about it—you use a product like shampoo all over your head. Why would a shampoo cause patchy hair loss? It just isn’t explainable on a medical basis.

What about an allergy?
If you are allergic to a product you’re using—be it a shampoo or a nail polish—you get dermatitis, which is an inflammation of the skin, wherever you apply the product. The typical signs are skin redness, swelling, flaking and itching. Hair loss is not a common sign of skin allergy in the absence of dermatitis.

If you think you are experiencing hair loss, what should you do?
The first thing you should do is go to your primary care physician. They can do an examination and order basic tests like checking your thyroid. If necessary they can then refer you to a specialist.

Hair loss is an emotionally charged issue, so patients who believe they are losing their hair are generally not calm about it. When patients call my office, they are alarmed. Most people who experience genetic hair loss don’t come in until it worsens and is difficult to hide. . What they do not know is that the earlier you treat it, the more hair follicles you will save. There are many patients I wish I had seen ten years earlier. So my advice is don’t wait until your hair loss is really bad to see your doctor.

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