American Medical Association Family Medical Guide - American Medical Association [767]
Disorders of the Hair and Nails
Hair and nails are dead, hardened structures that are similar chemically to the surface layer of your skin. The substance that gives both hair and nails their hardness is a protein called keratin, which is found in smaller amounts in the top layer of the skin. Hair grows from follicles, which are pits of actively dividing cells that occur in varying numbers in the skin. Nails grow from special folds in the skin. Disorders that affect the hair and nails are usually cosmetic and generally not harmful to health.
Hair
Hair is a threadlike structure composed of dead cells filled with keratin (a type of protein). Shafts of hair grow from tiny pits in the skin called hair follicles. The root of the hair is embedded in the skin and, in its growing phase, is firmly enclosed by live tissue called a bulb. Hair is surrounded by sebaceous (oil) glands and arrector pili muscles, which pull hairs erect.
Each hair consists of a central, spongy, semi-hollow core called the medulla. The medulla is surrounded by a layer of long, thin fibers called the cortex. On the outside of each hair are several layers of overlapping cells called the cuticle.
Dandruff
Dandruff is a condition in which small, dead flakes of skin develop on the scalp when skin cells grow unusually fast. The two main causes of dandruff are a mild form of seborrheic dermatitis (see page 1063) and, less frequently, psoriasis (see page 1064) of the scalp. The hair itself is not affected.
Treatment
To treat dandruff, use an over-the-counter antidandruff shampoo as often as recommended on the label (usually every day or every other day). Make sure the shampoo contains one or more of the following ingredients: tar, selenium, sulfur, salicylic acid, zinc, or ketoconazole. For best results, lather twice each time you shampoo (the first time for 1 minute, then rinse, and the second time for 5 minutes). If regular use of the shampoo does not clear up your dandruff, your doctor may prescribe a corticosteroid lotion, or a lotion that contains a higher concentration of one of the ingredients in the antidandruff shampoo to apply to your scalp.
Ingrown Hairs
Ingrown hairs (also known as shaving bumps, razor bumps, or pseudofolliculitis barbae; see page 121) are hairs that become trapped in hair follicles. They usually result from close shaving but can occur for unknown reasons. Ingrown hairs are common, especially on the face in men and in people who have curly hair.
Symptoms and Treatment
Ingrown hairs cause small, hard bumps or swellings around hair follicles. The bumps can become inflamed and painful if they become infected.
To treat inflamed ingrown hairs, your doctor may recommend applying an over-the-counter acne medication that contains benzoyl peroxide (which loosens the hair by causing the skin to peel) or an over-the-counter antibiotic cream. Your doctor may prescribe a stronger acne medication such as tretinoin, or topical or oral antibiotics. If the problem is severe, your doctor may recommend that you stop shaving or have the hair in the areas that you normally shave permanently removed by electrolysis.
Preventing Ingrown Hairs
You can prevent ingrown hairs from shaving by following these tips:
• Before shaving, wash the area gently with mild soap and a soft, clean washcloth and rinse thoroughly. Apply a very warm washcloth to the skin but do not dry the skin.
• Apply a nonirritating shaving cream or gel, or one that contains benzoyl peroxide.
• Use a safety razor (not an electric razor) with sharp blades. Replace the blades often, preferably after every two shaves.
• Experiment to find the shaving technique that works best for you. Always shave in the direction in which the hair grows.
• Don’t shave too closely; hold the razor lightly, and don’t press