If you aren't healthy, your hair isn't going to be healthy and it probably won't grow the 1/2 inch each month that is standard. If you are taking certain medications, have a crummy diet, don't keep your hair clean and protected and are an emotional wreck, it will show up in your hair just as it does in your eyes and in your skin.

You Are What You Eat

First and foremost, eat right. Make sure that your diet is replete with all of the vitamins and nutrients that are needed for healthy hair. A pro-hair health diet includes wheat, milk, eggs, green leafy vegetables, proteins, fruits, fish, carbohydrates and proteins. Hair is made up almost entirely of protein, so you need to have protein in your diet.

Take a daily supplement that contains vitamin B, as well as vitamins C, E and A. Make sure that you have adequate amounts of iron, zinc and magnesium in your diet (or get these minerals via a supplement.) The other B vitamins that are critical for hair health and growth are, according to Greenherbalremedies.com, folic acid, which is vitamin B9, and pantothenic acid, which is vitamin B5. Biotin (vitamin H) is considered one of the top, if not the top, vitamin for hair health. It is believed that these particular vitamins can speed up hair growth.

Protect Your Hair

Protect your hair from the sun just as you would protect your skin. If you're going to be outside for hours on end, wear a hat. Dead, dry hair is not going to growth lickety-split. Avoid cigarette smoke and other pollutants that are free radicals. When you take vitamins such as E and C, they provide some protection against free radicals because they are antioxidants. Cigarette smoke wrinkles your skin and it also deprives your hair of the ability to generate new pigment cells. So not only will your hair's health suffer from exposure to smoke, but smoke may make you turn gray faster.

Medications

Medications that may prevent your hair from growing and may also cause what hair you have to fall out include birth control pills, anti-depressants, anti-seizure medications, anti-inflammatory drugs, gout medicine, chemotherapy drugs and, of course, illicit street drugs. Drugs that affect hair growth are cytotoxic drugs, anti-androgens and drugs that act on potassium channels.

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Hirsutism and Hypertrichosis

According to Dermatology.cdlib.org, hirsutism, which is the growth of androgen-dependent hairs all over the body, can be caused by testosterone, metyrapone, anabolic steroids, glucocorticoids, some anti-epileptic drugs, ACTH and danazol. Hirsutism (see photo above) can result in hair growth on a woman's face and on her body.

Hypertrichosis (see photo), which is hair density or length that is beyond the accepted limits for a particular sex, race or age, can be caused by the medications minoxidil, diazoxide and cyclosporine.

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Illnesses

If you are anemic and have iron-poor blood, this is going to keep you from having an abundant head of hair. If you have an underlying illness, such as thyroid malfunction, this will affect the health as well as the growth of your hair.

Female Hormones

When estrogen levels are high (during pregnancy, for example), it may seem as though your your hair is growing faster or that you actually have more hair. Your hair is not growing faster, but you may be holding onto more hair than normal. During pregnancy, a woman does not shed the normal daily amount of hair (between 50 and 100 hairs). About three months after giving birth, you may notice a significant amount of hair loss, but this is only temporary and will correct itself. The loss occurs because the estrogen levels have dropped back down and you are losing all of the hair that you normally would have lost incrementally over a nine-month period of time.

Male Hormones

In an article written by Slobodan M. Jankovic and Snezana V. Jankovic called "The Control of Hair Growth," which was published in the Dermatology Online Journal, the authors note that androgens (male hormones) indirectly control hair growth. When blood androgen levels (and that includes testosterone and DHEA, which is dihydrotestosterone) are elevated, this can cause hair loss and certainly doesn't prompt hair growth, according to Wdxcyber.com. Women who are extremely sensitive to androgens may have the appropriate amount in their system yet find that their hair is falling out instead of growing. Ask your physician about methods available for lowering the amount of testosterone that's reaching your hair follicles.

Women who have too much testosterone (an androgen) may not have much hair on their heads but lots of hair on their faces and bodies, which isn't, of course, what they desire. Testosterone can be both good and bad. Testosterone is what prompts male characteristics to develop during a young boy's puberty; however, it turns around and does the opposite later on in life, prompting male pattern baldness.