The Harvard Medical School Family Health Guide
Skin, Hair, and Nails
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Toenail Problems

Your toenails reveal a lot about your overall health and can provide the first sign of a systemic disease. For instance, nails that are rounded inward like spoons rather than outward, may indicate a severe iron deficiency. Nails that are pitted and thick are a sign of psoriasis. If you notice any abnormality in your toenails, ask a foot care specialist about it.

Ingrown Toenails

An ingrown toenail is one of the most common sources of foot pain. It can be a serious problem for anyone with diabetes or circulatory difficulties.

An ingrown toenail develops when the side of the nail digs into the skin. This can lead to pain, irritation, swelling, and redness. The big toe is most often affected, although no toe is immune. The problem usually develops because the nails have not been trimmed properly. Overly tight shoes may also be a factor. Some people also have an inherited tendency for the problem.

The easiest way to prevent an ingrown toenail is to cut your nails straight across, rather than rounding off the corners. Use a toenail clipper (which is wider and larger than a fingernail clipper) or, if you use scissors, cut the nail in several short movements. Also, clean under your nails regularly with an orange stick. Wear shoes that provide enough room at the toes, and wear stockings or socks that allow your toes to move freely.

Treating Ingrown Toenails

You can treat this problem at home, unless you have diabetes. If you are a diabetic and have an ingrown toenail, you should see your doctor or foot care specialist immediately. Otherwise, if the problem is minor (the toe is irritated and red, but not overwhelmingly painful), soak your feet in warm water to soften the nail; then cut the part of the nail that is pressing against the skin. Trim gently, or you may hurt yourself.

Once that part of the nail is removed, apply a topical antibiotic, which you can purchase at any pharmacy. Wear open-toed sandals or roomy shoes to reduce pressure on the toe. If your toe isn’t better in three to five days, see a foot care specialist. Your toe may be infected, and you may need to start antibiotics and have the ingrown portion of the nail removed.

Toenail Fungus

Fungal nails are fairly common, but can go undetected for years. The problem develops when a fungus infects the area under the surface of a toenail. There are many types of fungal infections, which together account for half of all nail problems.

The moist, dark environment inside your shoes provides a perfect habitat for fungi. Infections are normally spread in damp areas where many people congregate — such as swimming pools and gyms, or even the shower or tub in your own home, if someone who uses it has the problem.

If a toenail becomes infected with a fungus, you may not realize it at first. The early signs are subtle. A scattering of white spots may appear across the nail. This should not be confused with the occasional white lines and crescents that can develop in healthy nails. With time, the toenail becomes thicker and a yellow-brown stain clouds the nail. White, green, and black flecks may also appear. The toes may smell. Untreated, the infection can spread to other toes, and may result in numbness, tingling, pain, and nails so thick that they are difficult to cut. The end of the nail may separate from the bed underneath, and the condition may become so painful that you have trouble walking.

To prevent fungal infection, avoid walking barefoot in heavily trafficked public areas, like the gym. (Wear sandals or “shower shoes.”) Wash your feet daily with soap and water and dry them thoroughly, especially between the toes. Put on a pair of clean socks every day, and change them more often if you sweat a lot or get your feet wet.

Treating Nail Fungus

If you have a mild infection (white spots or a small, defined stain), apply topical over-the-counter antifungal agents to suppress the infection. Be aware, however, that these topical medications do not always penetrate the nail to reach the underlying infection (which is the reason oral medications have long been the mainstay of treatment for fungal nails). If the stain does not disappear, seek medical attention.

Recent advances have greatly improved treatment of fungal nails. In 1999 the Food and Drug Administration approved a liquid form of ciclopirox (Penlac Nail Lacquer) as the first topical medication specifically intended for fungal nails. This prescription medication is applied daily, much like a nail polish, and takes 48 weeks to work.

Your doctor may prescribe a medication such as fluconazole (Diflucan), itraconazole (Sporanox), and terbinafine (Lamisil) that kills the fungus in about three months.

Be aware that the FDA recently issued a public health advisory warning that both Sporanox and Lamisil tablets can cause serious liver damage, resulting in liver failure and death. Sporanox has also been associated with a small risk of developing congestive heart failure. Although the FDA is still investigating, your doctor will likely do a baseline liver function test before prescribing either of these medications. If you do receive these pills, you will probably repeat the liver function tests six weeks after initiating therapy.

February 2003 Update

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How to apply sunscreen for maximum protection

Most families follow common medical advice and take along a bottle of sunscreen when they're spending a day in the sun. But how do you know if you're applying enough? Most people don't, but a letter published in the June 22, 2002, issue of the British Medical Journal may help clarify the amount of sunscreen you should use and how often you should apply it.

The letter, written by Drs. Steve Taylor and Brian Diffey, suggests people follow the "rule of nines" to get the sun protection factor (SPF) that's listed on the bottle. According to the rule, you should divide your body into 11 different sections, each making up about 9% of your total surface area:

  • Head, neck, and face
  • Left arm
  • Right arm
  • Upper back
  • Lower back
  • Upper front torso
  • Lower front torso
  • Left upper leg and thigh
  • Right upper leg and thigh
  • Left lower leg and foot
  • Right lower leg and foot

For sufficient protection, use a two-finger approach: cover each of the 11 sections with enough sunscreen to span the length of your pointer and middle fingers.

The authors admit that this is more sunscreen than most people feel comfortable wearing, so they suggest that people put on half that amount at one time, and then apply another dose a half hour later. Studies have shown that sunscreen users do not apply enough sunscreen to protect the whole body. As a result, the actual SPF is close to half that on the product label.

It's also worth noting that according to the American Academy of Dermatologists, staying out of the sun is the best way to prevent skin cancer. Because harmful sun rays like UVA and infrared get through sunscreen, you shouldn't think of it as a shield against the sun or use it as an excuse to stay out longer. Although sunscreen is an important part of sun protection, it is second to wearing a shirt and hat and avoiding sun exposure altogether (especially between the hours of 10 a.m. and 4 p.m.).

August 2002 Update

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