Why Is My Hair Falling Out?

Noticing more hair on your pillow lately? Or is your shower drain getting clogged faster than usual? If you’re worried about losing hair, you’re not alone. Dermatologist Shilpi Khetarpal, MD, explains how and why hair loss happens and what can be done about it.

Common reasons why your hair may be falling out

Think of hair growth like a cycle: It grows, rests, then sheds before growing again. At any given moment, each hair on your head is at a different point of that cycle — and that cycle takes time.

“Any major shedding you see today is the result of what happened three months ago,” says Dr. Khetarpal.

Some hair shedding is totally normal. But excessive shedding is often a sign that your body is going through other changes.

Here are some of the most common causes of hair loss:

1. Stress

Stress is a leading cause of hair loss. Increased levels of cortisol (the stress hormone) force your hair follicles into a resting period, which causes them to fall out earlier than usual.

If you were dealing with major stressors, like a divorce or the death of a loved one, it could cause your hair to thin and fall out — months after the damage started.

2. Hormonal changes

You may start losing hair a few months after giving birth. Or you could notice extra shedding during menopause. You might also notice some hair loss if you’re dealing with other hormonal changes related to:

• Starting or stopping hormonal birth control
• An over- or underactive thyroid
• Polyendocrine metabolic ovarian syndrome (PMOS)
• Insulin resistance
• The removal of one or both ovaries

3. Medical conditions

Anything that directly affects your health has the ability to impact hair growth. Smoking, for example, causes hair loss by reducing blood flow to your scalp — but it also has widespread negative effects for your body.

“Quitting smoking can improve your overall health and the health of your hair,” notes Dr. Khetarpal.

Some fleeting illnesses (like the flu) can also disrupt the hair growth cycle and trigger hair loss, especially if they cause a high fever.

“Any major shock to the body can cause you to start shedding two or three months later,” she adds.

Chronic conditions, like autoimmune diseases, have more lasting long-term effects because they tend to put a lot of stress on your body. Alopecia areata, for example, is a major cause of hair loss because your immune system attacks your hair follicles directly.

“Alopecia can occur anywhere on the body, including the scalp,” describes Dr. Khetarpal. “It often causes round, patchy areas that are completely hair-free.”

If you’re losing hair fast, it’s important to talk to your doctor in case something else is going on with your body (more on that later).

4. Nutrient deficiencies

Healthy hair depends on all kinds of nutrients to help it grow. So, if you have low levels of iron or you’re short on vitamin D or B vitamins, it could cause some level of hair loss.

“Your body needs certain vitamins and nutrients to build hair,” says Dr. Khetarpal. “If you have a deficiency, your doctor might recommend vitamins and supplements for hair growth.”

5. Medications

Chemotherapy targets fast-growing cancer cells. But because hair follicle cells grow and divide just as quickly, hair loss is often a side effect of the treatment.

Other common medications can lead to hair loss or thinning, too, especially if they’re used long-term. These include:

• Antibiotics
• Antidepressants
• Beta-blockers
• Blood thinners
• Blood pressure medications
• Hormonal therapies

6. Hair care and styling habits

The way you wash or style your hair can affect hair growth. For example, consistently putting your hair into tight styles like braids or ponytails, or frequently using extensions or weaves, can lead to traction alopecia. This type of permanent hair loss occurs when your hair is pulled by the root and stops growing.

Other habits that lead to hair loss and damaged or brittle hair include:

• Excessive use of bleach and other harsh chemical treatments
• Overuse of high-heat dryers, curling irons or straighteners
• Washing hair too frequently or not enough

When to see a doctor

If you’re worried about how much hair you’re losing, talk to a healthcare provider right away. It could be an early sign of some other condition. And with conditions like alopecia, the sooner you seek treatment, the better your chances of managing hair loss.

“The longer your hair is gone, the harder it is to get back,” says Dr. Khetarpal. “It’s important to have a discussion with your doctor to find what’s causing it and start the right treatment.”