Hair loss sounds innocuous enough, like middle-aged spread or crow's-feet, something to tut-tut about and put down to passing years. But for many who look in the mirror one morning and realize that a thinning crown has turned into a glaring bald spot, the discovery can be a shock. That's why more and more men-and many women-are taking advantage of the latest in hair transplantation techniques.

According to Dr. Joseph Greco of The Center for Sight, who has written and lectured about hair transplants for years, 19 out of every 20 men suffer from hair loss at some point in their lives, and a sizeable number of those seek out hair transplant experts to fix the problem. "It's the No. 1 cosmetic surgery in males today," says Greco.

But surgery is not the only option, and selecting the best solution from the extensive menu of choices can be confusing. Type "hair loss" on an Internet search engine, and a dizzying number of links pops up.

Hair loss has spawned a $3-billion-a-year industry, says Dr. Brett Hirsch, a Sarasota osteopathic doctor who has 15 years of cosmetic work under his belt and has done about 4,000 hair transplant surgeries. It's an industry that touts everything from herbal remedies (whose efficacy is unproven) to $800 "laser combs" to restore scalp circulation on late-night infomercials and online banner ads. "Hair loss is a very emotional problem; so, very often, we have these companies feeding on the fact that people will do anything," says Hirsch.

A dermatologist is often the best first contact, advises Dr. Bobby Limmer, president of the International Society of Hair Restoration Surgery, an organization that numbers more than 700 hair transplant specialists across the world. "If you're thinking about hair restoration, ask the doctor to give nine or 10 patient references," says Limmer, a San Antonio dermatologist. "Call them and visit them and see them in person."

Limmer's Web site and the site of the American Academy of Dermatology are excellent starting sources for researching hair loss and can direct patients to doctors in their area. Seek out a doctor who specializes in hair loss or has intensive experience with hair transplant surgery.

Once you've done that, the next step is to determine the reasons for the hair loss. There are a surprising number and variety of factors to consider, ranging from hormone levels and medications to hereditary patterns and nutrition. A common cause of hair loss in women is hormonal imbalance caused by a recent pregnancy, menopause or a sudden cessation in taking oral contraceptives. While mere stress is rarely the primary cause of hair loss-other hoary chestnuts include wearing hats, and dirt and sweat-some sort of trauma, such as years of using damaging chemicals on your hair or radiation treatment for cancer, can cause hair to fall out.

Nutrition can also affect the health of hair; those on rigid diets with not enough protein might find their hair thinning. Lack of iron can also cause hair loss, which is why women who suffer from heavy menstrual periods might find their hair thinning. Medical conditions like hypo- and hyperthyroidism can also contribute, as can severe and prolonged fever and flu.

Lately, doctors also have been seeing a more modern cause of hair loss in women: More and more women are asking for treatment to rectify uneven hairlines caused by plastic surgery, to cover up scars and to reinstate follicles damaged during a face lift.

However, the most common cause of hair loss is still old-fashioned hereditary balding, also known as typical male-pattern baldness. According to information from the American Academy of Dermatology, our hair goes through different resting and growing phases. About 10 percent of our hair is in the resting phase at any given time. Then it is shed and replaced by a new hair from the same follicle. The presence of a hormone called DHT affects the process: Some people's follicles are simply genetically predisposed to soak up an inordinate amount of DHT, causing hair to go into longer and longer resting phases.

Treatments can be non-surgical or surgical. Although many drugs claim to stop hair loss, the only two FDA-approved, proven treatments are Propecia and Rogaine. Propecia is an oral medication, effective in men only, that comes in the form of a pill taken every day. Both men and women can use Rogaine, or monoxidil as it's also known. Rogaine is a topical cream applied directly to the scalp to stimulate hair growth. Doctors can suggest taking one or both together. Although local doctors say they hear few complaints about side effects, Rogaine can cause itching and redness of the scalp; and a small number-fewer than one percent-of people who take Propecia complain about decreased sexual desire.