Rapid hair loss is often a strong sign that you ought to have a battery of tests to evaluate your nutrition, health, and hormone levels. And that makes an important point: Hair loss isn't just an appearance issue; it can be a sign that something wacky is going on elsewhere in your body. Inflammation in the scalp, from an overdose of sun or from seborrheic dermatitis, can speed up hair loss. More often than not, it's a hormone issue—especially one involving your thyroid gland. In women especially, it's common to experience a decline in thyroid hormone (that's called hypothyroidism), where some of your bodily systems slow down. Scalp hair loss or facial hair growth is a sign that you should have your hormone levels checked. We recommend having your thyroid-stimulating hormone checked every other year if you're losing hair, or, for all others, once at age 20, then at age 35, and every other year after age 50 (TSH is the trigger from the brain that tells your thyroid gland to make thyroid hormone). If your level of thyroid hormone is low or if it's normal but you are experiencing thyroid-related symptoms, you can be (and usually need to be) treated with a synthetic (sometimes bioidentical) hormone. You'll need to be rechecked six weeks later to see if the supplemented dose is enough. For a man, a decline in the need to shave signals a decrease in testosterone (for a woman, it's the same clue if she needs to shave her legs less often).
How Hair is Destroyed
Our hair occasionally needs lubrication the way other parts of our bodies do. But with hair, the things many of us do to help it are actually hurting it. Most of us treat shampoo as if it's toothpaste for our head—we've got to use it every day. But that doesn't have to be the case. Some people find that their hair has just as much body and shine without shampooing every day (and they like the fact that they can take a break from putting additional chemicals on their head). On the other hand, if shampooing is a Zen experience for you, its calming benefits may well do more for you than its hair-stripping effects, so we can't argue with daily shampoos (you can also use conditioner alone). See below for our specific recommendations for hair-washing.
Now, here's some information that's going to make your hair stand up. Artificial coloring on your head—whether you're bleaching it or coloring it—is the equivalent of artificial coloring in food: It may make it look as pretty as can be, but it's not always the healthiest thing you can do to your head. There is some suspicion that permanent black hair dye can cause leukemia and lymphomas and some chemicals that are no longer used caused bladder cancer. So the purple Mohawk you're considering? It's probably fine for your health (temporary hair dyes are safer than permanent dyes), though probably not for your next job interview. Bleaching, on the other hand, will really run up your hair bill as you try to salvage permanent damage.
Here's why: The pigment of your hair comes from the inner two layers. When you bleach your hair, you damage the shingles that create the covering of the hair shaft. The dye, which slips through the gaps in the outer layers, swells to give your hair a different color. But the prior or current damage the bleach caused allows the dye to slowly slip out of the hair, so you end up losing the full body of the hair faster than if you just left it alone.
Hair Today, Gone Tomorrow