More than 80 percent of men and nearly half of women experience significant hair loss during their lifetime. For many, the thinning starts well before middle age. Dermatologist Jerry Shapiro, MD, an internationally renowned expert and leading researcher on hair loss in the Ronald O. Perelman Department of Dermatology at NYU Langone, discusses the causes and treatment of this surprisingly complex problem.

It’s Not Just an Age Thing

A typical scalp bears some 100,000 to 150,000 hairs. Normally, between 50 and 100 of them fall out daily as they complete their growth cycle. “When shedding outpaces growth,” explains Dr. Shapiro, “the result is alopecia,” the medical term for hair loss. The most common type in both men and women occurs when follicles become overly sensitive to a hormone and deteriorate. As a result, the growth phase shortens until it finally stops. Although alopecia becomes more prevalent with advancing years, it affects one in four men by age 30.

Physical and Emotional Stresses Can Play a Role

Alopecia causes 95 percent of cases of hair loss in men, and about 40 percent in women. But hair loss can have many other causes. Some people suffer from an autoimmune disorder that causes scattered bald patches. Shedding can also be triggered by unusual stress. “I call it the three Bs: bereavement, bankruptcy, or a breakup,” says Dr. Shapiro. Other culprits include chemotherapy, pregnancy, menopause, anabolic steroids, cigarette smoking, high doses of vitamin A, and some prescription medications. Compulsive hair pulling or tight ponytails can do it, too. “See a doctor if you notice abundant hair where you wouldn’t normally see much, such as on your pillow,” Dr. Shapiro advises.

Diagnosis May Require Some Sleuthing

Diagnosis begins with a detailed patient history, possible triggering events, and a list of relatives with hair loss. Next comes an examination of the scalp. A dermatologist may perform a hair pull to see how many strands break off, or use a device to inspect hairs microscopically without removing them. The doctor may also order blood tests and check the patient for skin disorders or signs of hormonal problems (such as excess facial hair in women).

Treatment Options Include Medication and Surgery

If shedding is caused by illness, hair often grows back once the underlying problem is resolved. For male-pattern hair loss, there are two FDA-approved medications; for female-pattern hair loss, there’s only one. The most effective—and only permanent—treatment, however, is a hair transplant: a dermatologist harvests healthy follicles from areas of dense growth and implants them where they’re needed. NYU Langone’s Hansjörg Wyss Department of Plastic Surgery offers an approach that is less invasive, extracting follicles with air pressure and suction rather than incisions. Says Dr. Shapiro: “The results can be dramatic.”