Hair Loss (Alopecia)

What is Hair Loss (Alopecia)?

Hair loss, also called alopecia, happens when hair falls out faster than it can grow back. Everyone loses about 50 to 100 hairs per day as part of the normal hair growth cycle. But when you lose more than that, you may notice thinning or bald patches.

There are many types of hair loss. Some are temporary and reversible, while others are permanent. Androgenetic alopecia, also called pattern baldness, is the most common type. It affects both men and women as they age. Other types include alopecia areata, which causes patchy hair loss, and telogen effluvium, which is temporary shedding triggered by stress or illness.

Hair loss can result from genetics, hormones, nutrient deficiencies, medications, or underlying health conditions. Understanding the root cause is key to finding the right treatment. Blood tests can help identify nutritional gaps, hormone imbalances, and thyroid problems that may contribute to hair loss.

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Symptoms

Gradual thinning on top of head, especially in men and women as they age
Circular or patchy bald spots on the scalp, beard, or eyebrows
Sudden loosening of hair, with handfuls coming out when washing or brushing
Full-body hair loss, sometimes due to medical treatments like chemotherapy
Patches of scaling that spread over the scalp, sometimes with broken hair
Wider part or ponytail that looks thinner than before
Receding hairline at the temples or forehead
Excess hair on your pillow, in the shower drain, or on your hairbrush

Some people experience hair loss gradually over months or years without noticing early changes. Others see sudden or dramatic shedding after stressful events, illness, or medication changes.

Causes and risk factors

Hair loss has many possible causes. Genetics play the biggest role in pattern baldness, which tends to run in families. Hormonal changes during pregnancy, childbirth, menopause, or thyroid problems can trigger temporary or permanent hair loss. Certain medications, including blood thinners, antidepressants, and blood pressure drugs, list hair loss as a side effect. Medical conditions like autoimmune diseases, scalp infections, and skin disorders can also damage hair follicles.

Nutritional deficiencies are an often-overlooked cause of hair loss. Low levels of iron, biotin, zinc, and protein can weaken hair and slow growth. Severe stress, both physical and emotional, can push hair follicles into a resting phase. This leads to shedding about three months later. Tight hairstyles, harsh chemical treatments, and frequent heat styling can damage hair and cause breakage or traction alopecia.

How it's diagnosed

Doctors diagnose hair loss by reviewing your medical history and examining your scalp. They may ask about recent stress, medications, diet changes, and family history of hair loss. A pull test, where the doctor gently tugs on several hairs, can help determine if shedding is excessive. Scalp biopsies or microscope examinations of plucked hairs may be needed in unclear cases.

Blood tests can identify underlying causes of hair loss. Tests for thyroid function, iron levels, and vitamin deficiencies like biotin can reveal nutritional or hormonal imbalances. Hormone testing may check testosterone, estrogen, and other markers linked to pattern baldness. Talk to a doctor about testing if your hair loss is sudden, patchy, or accompanied by other symptoms. While specialized testing for hair loss may go beyond standard panels, identifying nutrient gaps is an important first step.

Treatment options

Eat a balanced diet rich in protein, iron, zinc, and biotin to support hair growth
Manage stress through regular exercise, meditation, or therapy
Avoid tight hairstyles, harsh chemicals, and excessive heat styling
Use gentle, sulfate-free shampoos and conditioners designed for thinning hair
Consider minoxidil, an over-the-counter topical treatment that promotes regrowth
Ask your doctor about finasteride, a prescription medication for male pattern baldness
Treat underlying conditions like thyroid disorders or iron deficiency
Explore corticosteroid injections for alopecia areata, an autoimmune type
Look into platelet-rich plasma therapy or laser devices, though evidence is still emerging
Consult a dermatologist about hair transplant surgery for permanent hair loss

Frequently asked questions

Androgenetic alopecia, or pattern baldness, is the most common cause. It affects about 50 million men and 30 million women in the United States. This type is genetic and tied to hormones called androgens. It usually happens gradually as you age.

Yes, blood tests can identify several underlying causes of hair loss. Tests for thyroid function, iron levels, and biotin can reveal hormonal imbalances or nutritional deficiencies. Vitamin D, zinc, and hormone panels may also provide clues. However, some types of hair loss require a scalp exam or biopsy for diagnosis.

Hair loss from stress is usually temporary. This condition, called telogen effluvium, happens when stress pushes hair follicles into a resting phase. Shedding typically starts two to three months after the stressful event. Once the stress is managed, hair usually regrows within six to nine months.

Biotin, also called vitamin B7, helps your body make keratin, the protein that forms hair. Low biotin levels can lead to hair thinning and loss. Biotin deficiency is rare but can happen with certain medications or digestive conditions. A blood test can check your biotin levels.

Yes, both an overactive and underactive thyroid can cause hair loss. Thyroid hormones regulate metabolism and hair growth cycles. When thyroid levels are off, hair may become dry, brittle, and thin. Treating the thyroid condition usually helps hair regrow.

Yes, low iron levels can disrupt hair growth. Iron helps red blood cells carry oxygen to your tissues, including hair follicles. Women with heavy periods, vegetarians, and people with digestive issues are at higher risk. Blood tests can measure iron and ferritin levels to detect deficiency.

Most treatments take at least three to six months to show results. Hair grows slowly, about half an inch per month. Minoxidil and finasteride typically require four months of consistent use before you notice improvement. Treating nutritional deficiencies may take several months to impact hair growth.

Yes, eating a nutrient-rich diet supports healthy hair growth. Focus on foods high in protein, iron, zinc, and biotin. Good sources include eggs, nuts, seeds, leafy greens, fish, and lean meats. Severe calorie restriction or crash diets can trigger temporary hair loss.

Yes, pattern baldness looks different in men and women. Men typically see a receding hairline and bald spots on the crown. Women usually experience overall thinning, especially along the part, but rarely go completely bald. Women also experience hair loss from hormonal shifts during pregnancy and menopause.

See a doctor if hair loss is sudden, patchy, or accompanied by itching, pain, or skin changes. Also seek care if you notice hair loss after starting a new medication or if it affects your eyebrows or other body areas. Early evaluation can help identify treatable causes and prevent further loss.