Last reviewed by Faculty of Harvard Medical School on January 24, 2013
By Harvey B. Simon, M.D.
Harvard Medical School
It lacks the pain of a heart attack, the threat of prostate cancer, and the complications of high blood pressure. Still, despite the best efforts of Michael Jordan and all of the trendy guys who've followed his shiny-scalp example, millions of men are distressed by hair loss.
A man's scalp is covered by about 100,000 hair follicles. During the normal hair-growth cycle, each follicle passes through a two- to three-year period of growth, followed by a period of involution and rest that lasts from three to four months. During the involution phase, some of the follicles die, which is why a healthy scalp loses about 100 hairs a day. But most of the follicles get back to growing new hairs, so a man's hair stays full unless something goes wrong.
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Abnormal Hair Loss
Hair follicles contain living cells; like all cells, they can be damaged. Damaged follicles stop growing hair. If the problem is mild, the follicle recovers and resumes hair growth. For example, severe physical or emotional stress can damage hair follicles, halting hair growth. That's why patients often lose hair two or three months after a major illness or traumatic life event. This type of hair loss is called telogen effluvium. It's easy to recognize with a simple pull test: If you can extract more than five or six hairs with a single pull, you're likely to have telogen effluvium, and your hair is likely to grow back within a few months, even without treatment.
But severe damage may permanently stop hair growth. For example:
- Medication can damage hair follicles; chemotherapy drugs are the leading examples. Less often, toxic chemicals, radiation or infection can cause hair loss.
- Skin diseases that leave scarring can also lead to hair loss that may be permanent.
These problems are all uncommon. Contrary to popular belief, common woes like seborrhea (a skin condition marked by an itchy red rash and white scales) and dandruff do not cause hair loss.
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Call it androgenic alopecia and it sounds like a disease. But by age 50, half of all healthy men have male pattern baldness. It may cause anguish, but it's just part of the human condition, an accident of genes and hormones.
Male pattern baldness usually begins with a receding hairline, a bald spot at the top of the scalp, or both. It may start as early as ages 15 to 20 or as late as ages 40 to 50. It can progress slowly or swiftly, producing anything from thin hair to complete baldness that usually spares the sideburns and collar area.
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Most experts believe that one gene is responsible for androgenic alopecia, but it has variable penetrance, so it's more likely to produce hair loss in some men than others. The abnormal gene can be passed down from a mother or father to sons or daughters. But men are much more likely to suffer from the gene's activity because they have the second requirement, testosterone.
Testosterone, of course, is the male hormone that acts on tissues to produce the deep voice, strong muscles and bones and genital structures that characterize men. Testosterone acts directly on these tissues but to act on the hair follicles (and the prostate) it must be converted to the hormone dihydrotestosterone (DHT).
DHT stimulates the growth of hair follicles in the beard and body, but it has the opposite effect on the scalp. Add DHT to the right (or wrong!) genes and you've got male pattern baldness.
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Treatments for Baldness
Doctors don't think of male pattern baldness as an illness but 33 million American men are troubled enough to spend about $1.5 billion a year on treatments.
Some men turn to scalp surgery and hair transplants, others to wigs and toupees. But the Holy Grail is a pill or potion that can cover a shiny pate with a man's own hair.
In 1989, the U.S. Food and Drug Administration cleared the shelves of many worthless products marketed to gullible and vulnerable men for generations. But two medications remain standing; both can help, but neither is a miracle cure for baldness.
- Minoxidil tablets are a prescription drug for hypertension. But for more than 10 years it has also been available as Rogaine, a nonprescription lotion for hair loss. It works by prolonging the growth phase of hair follicles that are still active but its benefits last only while you use it regularly. Rogaine is more effective for bald spots than receding hairlines, but it's only partially effective at that. In one study, 36% of men who had used the product for several years felt it was worth the time and money. According to the manufacturer, Rogaine should be applied twice daily. Scalp irritation can occur; dizziness and low blood pressure are less common side effects.
- Finasteride is an oral prescription medication that blocks the conversion of testosterone to DHT. It is marketed as Propecia, which is a 1-milligram tablet. (The 5-milligram tablet is known as Proscar, and is prescribed for benign prostatic hyperplasia (BPH).)Propecia was approved largely on the basis of four studies. Although the drug had positive results, they were hardly dramatic. For example, after a year of treatment, men taking Propecia had an average of 876 hairs in a one-inch circle on the scalp, while those taking a placebo pill had 769 hairs. In another trial, 50% of men taking Propecia and 30% of men taking a placebo pill thought their appearance had improved.
Because Propecia cannot revive hair follicles that are inactive, it won't help men who are already bald. Men who find the drug helpful will have to continue taking it indefinitely to maintain even modest improvements. Propecia is generally safe, but 1% to 2% of men experience diminished sexual drive (libido) and potency, which rebound when they stop taking the drug.
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To Treat of Not To Treat?
From a medical point of view, there is no need to treat male pattern baldness. At best, the treatments are expensive and only partially effective. Although treatment is generally safe, some men may experience side effects. Take a look in the mirror and think it over. And before you decide, try to imagine how Michael Jordan, Bruce Willis, Chris Daughtry or Kobe Bryant would look with a bit of hair.
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Harvey B. Simon, M.D. is an Associate Professor of Medicine at Harvard Medical School and a member of the Health Sciences Technology Faculty at Massachusetts Institute of Technology. He is the founding editor of the Harvard Men's Health Watch newsletter and author of six consumer health books, including The Harvard Medical School Guide to Men's Health (Simon and Schuster, 2002) and The No Sweat Exercise Plan, Lose Weight, Get Healthy and Live Longer (McGraw-Hill, 2006). Dr. Simon practices at the Massachusetts General Hospital; he received the London Prize for Excellence in Teaching from Harvard and MIT.