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Powered by information and insights from The Merck Manuals

Vol. 1 — 2005

The Dark Side of Sunlight Identifying the Bumps and Spots on Your Skin Common Skin Disorders

Skin Cancer Safeguard Dogs and Cats from Summer’s Pesky Critters Summer Rashes and Bites

Our expert helps you to recognize the different types of skin cancers

The Dark Side of Sunlight: Skin Damage and Premature Aging


Basking in the warm summer sun might feel good, but ultimately, your health may suffer.

uring the summer, you probably spend most of your time outside. But whether you bake in the sun at the beach or simply catch some rays while you jog, picnic, or do errands, your health may pay a price. Too much sun exposure can increase your chances for skin cancer. In fact, 1 in 5 Americans will eventually develop skin cancer, according to the American Academy of Dermatology. The good news is that you can take steps to protect your skin from the sun’s damaging rays.


Sunlight and Skin Damage The skin shields the rest of the body from the sun’s rays. Ultraviolet (UV) light, although invisible to the human eye, is the component of sunlight that has the

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most effect on skin. UV light in small amounts is beneficial, because it helps the body produce vitamin D. However, larger amounts of UV light damage DNA (the body’s genetic material) and alter the amounts and kinds of chemicals that the skin cells make. The skin undergoes certain changes when exposed to UV light to protect against damage. The epidermis (the skin’s uppermost layer) thickens, blocking UV light. The melanocytes (the pigmentproducing skin cells) make increased amounts of melanin, which darkens the skin, resulting in a “tan.” The more sun exposure a person has and the fairer his skin, the higher the risk of skin cancers. The key to minimizing the damaging effects of the sun is avoiding further sun exposure; damage that is already done is difficult to reverse. Moisturizing creams and makeup help hide wrinkles. Chemical peels, alphahydroxy acids, and laser skin resurfacing may improve the appearance of thin wrinkles and irregular pigmentation. Deep wrinkles and significant skin damage, however, are unlikely to be reversed.


Sunburn Sunburn results from a brief (acute) overexposure to UV light. The amount of sun exposure required to produce a burn varies with each person’s pigmentation and ability to produce more melanin.

The skin undergoes certain changes when exposed to UV light to protect against damage.

Sunburn results in painful reddened skin. Severe sunburn may produce swelling and blisters. Symptoms may begin as soon as one hour after exposure and typically reach their peak after one day. Some severely sunburned people develop a fever, chills, and weakness and on rare occasions even may go into shock

(characterized by low blood pressure, fainting, and profound weakness). Several days after a sunburn, people with naturally fair skin may have peeling in the burned area, usually accompanied by itching. These peeled areas are even more sensitive to sunburn for several weeks. The best – and most obvious – way to prevent sun damage is to stay out of strong, direct sunlight. Clothing and ordinary window glass filter out most of the damaging rays. Water is not a good filter: ultraviolet A (UVA) and ultraviolet B (UVB) light can penetrate a foot of clear water. Clouds and fog are also not good filters of UV light; a person can get sunburned on a cloudy or foggy day.

Before exposure to strong direct sunlight, a person should apply a sunscreen, an ointment or cream containing chemicals that protect the skin by filtering out UV light. Sunscreens contain substances, such as para-aminobenzoic acid (PABA) and benzophenone, that absorb UV light. Sunscreens containing PABA must be applied 30 to 45 minutes before going out in the sun or into the water. Many sunscreens contain both PABA and benzophenone or other chemicals; these combinations provide protection from a broader range of UV light. Many sunscreens claim to be either waterproof or waterresistant, but most of these nonetheless require more frequent application in people who are swimming or sweating.


In the United States, sunscreens are rated by their sun protection factor (SPF) number – the higher the SPF number, the greater the protection. Sunscreens rated between 0 and 12 provide minimum protection; those rated between 13 and 29 provide moderate protection; those rated 30 and above provide maximum protection.

Cold tap water compresses can soothe raw, hot areas, as can skin moisturizers without anesthetics or perfumes that might irritate or sensitize the skin. Certain anti-inflammatory drugs help relieve pain and inflammation. Corticosteroid tablets also may help relieve the inflammation but are used only for the most serious burns. Specific antibiotic burn creams are required only for severe blistering. Most sunburn blisters break on their own: they do not need to be popped and drained unless they are still intact after three or four days. Sunburned skin begins healing by itself within several days, but complete healing may take weeks. After burned skin peels, the newly exposed layers are thin and initially very sensitive to sunlight and must be protected for several weeks. ■

Aging and The Skin

Information contained in this article comes from The Merck Manuals. For more information, visit skincancer or search The Merck Manual Home Edition.

Are Tans Healthy? In a word – no. Although a suntan is often considered an emblem of good health and of an active, athletic life, tanning for its own sake has no health benefit and is actually a health hazard. Any exposure to UVA or UVB light can alter or damage the skin. Long-term exposure to natural sunlight causes skin damage and increases the risk of skin cancer. Exposure to the artificial sunlight used in tanning salons is harmful as well, even though the UVA lights used in these establishments are somewhat less likely to produce skin cancer. Quite simply, there is no “safe tan.” Self-tanning, or sunless, lotions do not really tan the skin but, rather, stain it. They therefore provide a safe way to achieve a tanned look without risking dangerous exposure to UV rays. However, because they do not increase melanin production, self-tanning lotions do not offer protection from the sun. Therefore, sunscreens should still be used during exposure to sunlight. Results with the use of self-tanning lotions may vary, depending on a person’s skin type, the formulation used, and the manner in which the lotion is applied.

As people age, the skin tends to become thinner, less elastic, drier, and finely wrinkled. However, exposure to sunlight over the years contributes to wrinkling and to making the skin rough and blotchy. The effects of exposure to sunlight can be seen when skin that is normally exposed to sunlight, such as that on the face, is compared with skin that is usually covered, such as that on the buttocks. People who have avoided exposure to sunlight often look much younger than their actual age. The layer of fat under the skin thins and is replaced by more fibrous tissue. The fat layer acts as a cushion for the skin, helping protect and support it. The fat layer also helps conserve body heat. As this layer thins, the skin is torn more easily, wrinkles are more likely to develop, and tolerance for cold decreases.

The number of sweat glands and blood vessels also decreases, and blood flow in the deep layers of the skin decreases. Normally, heat is moved from the inner parts of the body through blood vessels to the surface of the body. When blood flow decreases, less heat leaves the body, and the body cannot cool itself as well. Thus, older people are more likely to develop disorders due to overheating, such as heat stroke. Also, the skin tends to heal more slowly when blood flow is decreased. The number of pigment-producing cells (melanocytes) decreases. Thus, the skin has less protection against ultraviolet (UV) radiation, such as that from sunlight. Information contained in this article comes from The Merck Manuals. For more information, visit or search The Merck Manual Home Edition.

The number of nerve endings in the skin decreases. As a result, sensation, including sensitivity to pain, may be reduced, and injuries may be more likely.


Identifying the Bumps and Spots on Your Skin kin growths are common among older people. Most are noncancerous (benign). That is, they may enlarge, but they do not spread to other parts of the body. Common noncancerous growths include age spots, most moles, seborrheic warts (seborrheic keratoses), skin tags (acrochordons), and cherry angiomas (hemangiomas). What causes these growths is unclear.


Age spots are light brown, flat spots, similar to freckles. They develop after years of exposure to the sunlight. Thus, they appear most often on areas usually exposed to sunlight – the hands, forearms, and face. They are sometimes called liver spots, although they are unrelated to the liver. Dermatologists can recommend creams or ointments that may lighten the spots after several weeks of frequent, regular applications. A mole is a colored (usually dark), painless spot that can be flat or raised. They can appear anywhere on the body. Once formed, moles remain for decades. Most moles are harmless, but some become cancerous.


A seborrheic wart is a small, rough, irregularly shaped, fleshcolored or dark bump. The surface is waxy or scaly. It can look pasted or stuck on to the skin. These warts usually appear during middle or old age, usually on the torso and temples.

seborrheic warts

Skin tags are soft, flesh-colored or dark bumps that may be connected to the skin by a stalk. Most often, they develop on the neck or in the armpit. continued on page 27

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From the Guest Editor Ellen S. Marmur, M.D. Chief of the Division of Dermatologic & Cosmetic Surgery Mount Sinai Medical Center, New York City



of Skin Self-Exams


When performing a self-exam, remember to inspect every inch of your body.

Knowing the basics of early skin cancer detection is the key to survival. Whether you’ve spent your summer in the sun or have avoided the outdoors for the past 10 years, it is wise to check your skin regularly. Skin cancer is the most common form of cancer, accounting for nearly half of all the cancers in the United States. Every year, more than one million Americans develop skin cancer, and the number one preventable cause is sun damage. But many cases of skin cancer could be prevented if more people followed simple precautions, such as wearing a broad-spectrum sunscreen or sunblock and a widebrimmed hat. Even with the best efforts, however, sometimes our past exposure to the sun can come back to haunt us. Many people have freckles, birthmarks, and moles on their

skin, the majority of which are normal. Some growths and spots, particularly moles, however, may be skin cancer. Recognizing new or suspicious growths is important in potentially spotting cancer early. Self-examination of your skin is the best way to detect the early warning signs of skin cancer. This is vital because the sooner it is caught, the better the chances for successfully treating it.

There are three types of skin cancer: Basal cell carcinoma, the most common skin cancer, can vary greatly in appearance. For example, it may appear as a pearly-pink plaque or sore that doesn’t heal. Squamous cell carcinoma often appears as a raised bump that may break open and form a scab in the center. It is more likely to invade the deeper layers of the skin.


Melanoma, the deadliest form of skin cancer, can have many features and is likely to spread to other parts of the body if not treated early.

ABCDs of Self-Exams Which moles might be suspicious? When performing a self-exam, remember the ABCDs:

Asymmetrical – If you drew a line down the middle of a suspicious mole, it would not create matching halves. Borders – Edges appear uneven, scalloped, or like an “oil slick”.

Color – Multiple colors or different shades of brown, black, red, blue, gray, or white.

Diameter – Larger than a pencil eraser (about six millimeters or one-fourth inch).

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The ABCDs of Skin Self-Exams continued from page 11

In my practice, I also recommend that patients look for other signs of skin cancer, including moles that suddenly rise, easily bleed, or have white circles around them.

Most of the time, melanomas and

Skin Self-Exam From Head to Toe

other skin cancers can be easily

When performing a skin self-exam, look for any changes in existing moles, the appearance of new ones or anything that seems unusual. For the exam, you will need a bright light, a full-length mirror, a hand-held mirror, two chairs or stools, and a hair-dryer.

spotted with a monthly self-exam. If you spot any new, suspicious, or unusual growths on your skin, see changes in the size, color, or texture of old moles or skin growths, or have a cut or wound

Inspecting From Head to Toe

Examine your head and face.

that doesn’t seem to heal, contact a dermatologist or other healthcare professional. When it is

When performing a self-exam, remember to check every inch of your body – from the top of your head to the bottom of your toes. Suspicious moles can appear on any part of the body, not just areas that have been exposed to sunlight. The goal is to look for any changes in existing moles, the appearance of new ones, or anything that seems unusual. Start with your head and face. Inspect your scalp using a hairdryer to part your hair, then inspect the rest of your face, neck, ears, mouth, and lips. Even examine your eyes since melanoma can sometimes begin in the eye. Use a mirror to check hard-to-see spots, such as your back and shoulders.

detected at an early stage, skin cancer can be treated effectively most of the time, and is usually curable. However, once the cancer spreads to other parts of the body, it is difficult to stop and can be deadly. Just as breast self-exams have helped women detect breast cancer early, when the chances for

Inspect your neck, chest, and stomach. Women also should check under their breasts.

survival are the greatest, skin selfexams can help many men and women catch skin cancer early before it becomes a serious concern. Both the National Cancer Institute and American Academy of Dermatology recommend that people perform skin self-exams every month. This, along with yearly skin checks by a dermatologist, is your best line of

Also examine spots that might not seem obvious, such as your underarms, fingernails, between the toes, the buttocks, the groin, and the soles of your feet. Women also should check under their breasts.

Check your hands, including fingernails, and your elbows, arms, and underarms.

defense for protecting your skin

With your back to the mirror, use the hand mirror to inspect the back of your neck, shoulders, upper arms, back, buttocks, and legs.

health and lowering your chances for developing a potentially lifethreatening cancer. ■ Sitting down, check your legs and feet, including your soles, as well as your genitals.


Illustrations by John Riddle

Common Skin Disorders Information on skin conditions from dryness to rosacea. ost of the time, dry skin, unsightly growths, and other skin problems are nothing more than a cosmetic nuisance. But sometimes they may signal a more serious problem. Here’s information about some of the more common skin disorders and how to treat them.


Psoriasis Psoriasis usually starts as one or more small patches on the scalp, elbows, knees, back, or buttocks. The patches typically have thick, silvery scales, which tend to flake off. Some people never have more than one or two small patches, and others have patches covering large areas of the body. The psychologic distress caused by psoriasis can be severe.


People with rosacea should avoid...spicy foods, alcohol, coffee, and other caffeinated beverages.

Psoriasis persists throughout life but may come and go. Symptoms are often diminished during the summer when the skin is exposed to bright sunlight. Some people may go for years between occurrences. Flare-ups often result from conditions that irritate the skin, such as minor injuries and severe sunburn. Sometimes flareups follow infections, such as colds and strep throat. Flare-ups are more common in the winter and after stressful situations. Psoriatic arthritis produces joint pain and swelling.

Phototherapy (exposure to ultraviolet light) also can help clear up psoriasis for several months at a time. Traditionally, treatment has been with phototherapy combined with the use of psoralens (drugs that make the skin more sensitive to the effects of ultraviolet light). This treatment is called PUVA (psoralens plus ultraviolet A). Some doctors are now using narrow-band ultraviolet B (UVB) treatments, which are equally effective but avoid the need to use psoralens and the side effects they cause, such as extreme sensitivity to sunshine.



Nearly everyone with psoriasis benefits from skin moisturizers (emollients). Other topical agents include corticosteroids, often used together with calcipotriene, a vitamin D derivative, or coal or pine tar. Very thick patches can be

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thinned with ointments containing salicylic acid, which make the other drugs more effective.

Rosacea usually appears during or after middle age and is most common in people of Celtic or Northern European descent who have fair complexions. The skin over the cheeks and nose becomes red, often with small pimples. The skin may appear thin and frail, with small blood vessels visible just below the surface. The skin around the nose may thicken, making it look red and bulbous (rhinophyma), which is particularly



common in alcoholics. Occasionally, rosacea appears on the torso, arms, and legs rather than on the face. People with rosacea should avoid foods that cause the blood vessels in the skin to dilate – for example, spicy foods, alcohol, coffee, and other caffeinated beverages. Certain antibiotics taken by mouth relieve rosacea. Antibiotics that are applied to the skin are also effective. In rare cases, antifungal creams are used. Corticosteroids applied to the skin tend to make rosacea worse.

When the Skin Is Dry


Normal skin owes its soft, pliable texture to its water content. To help protect against water loss, the outer layer of skin contains oil, which slows evaporation and holds moisture in the deeper layers of skin. If the oil is depleted, the skin becomes dry.

Warts are caused by viruses. Most warts are harmless, although they may be quite bothersome. The exceptions are certain types of genital warts that sometimes cause cervical cancer in women. Warts are classified by their location and shape.

Dry skin (xerosis) is common, especially in people past middle age. Common causes are cold weather and frequent bathing. Bathing washes away surface oils, allowing the skin to dry out. Dry skin may become irritated and often itches – sometimes it sloughs off in small flakes and scales. Scaling most often affects the lower legs. Rubbing or scratching dry skin can lead to infection and scarring. A form of severe dry skin is called ichthyosis. Ichthyosis can be an inherited disorder or can result from a number of other medical problems, such as an underactive thyroid gland, lymphoma, AIDS, and sarcoidosis. The key to treating simple dry skin is keeping the skin moist. Taking fewer baths allows protective oils to remain on the skin. Moisturizing ointments or creams containing petroleum jelly, mineral oil, or glycerin also can hold water in the skin. Harsh soaps, detergents, and the perfumes in some moisturizers irritate the skin and may further dry it.

Taking fewer baths allows protective oils to remain on the skin.

When scaling is a problem, solutions or creams containing salicylic or lactic acid or urea may help remove the scales. For some forms of severe ichthyosis, creams containing substances related to vitamin A help the skin shed excessive scales.

Common warts (verrucae vulgaris), which almost everyone gets, are firm growths that usually have a rough surface. They are round or irregularly shaped; are gray, yellow, or brown; and are usually less than one-half inch across. Generally, they appear on areas that are frequently injured, such as the knees, face, fingers, and around the nails (periungual warts). Plantar warts develop on the sole of the foot, where they are usually flattened by the pressure of walking and are surrounded by thickened skin. They tend to be hard and flat, with a rough surface and well-defined boundaries. Filiform warts are long, narrow, small growths that usually appear on the eyelids, face, neck, or lips. Flat warts, which are more common in children and young adults, usually appear in groups as smooth yellow-brown, pink, or flesh-colored spots, most frequently on the face and tops of the hands. The beard area in men and the legs in women are also common locations for flat warts, where they may be spread by shaving. In general, warts can be removed with chemicals, cut off, frozen off, or burned off with a laser or electrical current.

Itching Skin disorders that cause severe itching include infestations with parasites (scabies, mites, or lice), insect bites, hives, atopic dermatitis, and allergic and contact dermatitis. Systemic diseases that can cause itching include liver disease, kidney failure,


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“ ”

The act of scratching can itself irritate the skin and lead to more itching, creating an itching-scratchingitching cycle.

lymphomas, leukemias and other blood disorders, and, occasionally, thyroid disease, diabetes, and cancer. Many drugs can cause itching. Itching is also common during the later months of pregnancy.

Often, contact with wool clothing or irritants, such as solvents or cosmetics, causes itching. Dry skin also can result from cold weather or prolonged exposure to water. Hot baths typically worsen itching. The act of scratching can itself irritate the skin and lead to more itching, creating an itchingscratching-itching cycle. Prolonged scratching and rubbing can thicken and scar the skin. Itching that lasts longer than a few days or that comes and goes frequently without an obvious cause usually requires testing. If an allergy is suspected, skin tests may be performed. The number of eosinophils, a type of white blood cell, may be checked as well, because a high number may indicate an allergic reaction. If a systemic disease is suspected, blood tests are usually performed to check liver function, kidney function, and blood sugar levels. Sometimes, the doctor may have a person discontinue one or more

drugs to see if the itching is relieved. A biopsy or skin scraping may help identify the cause, including an infectious one. For itching of any cause, bathing should be kept brief and preferably in cool or lukewarm water with very little or no soap. The skin should be patted dry gently rather than rubbed vigorously. Many people with itching benefit from an over-the-counter moisturizing cream applied right after bathing. The moisturizer should be odorless and colorless, because additives that provide color or scent may irritate the skin and even cause itching. Fingernails, especially children’s, should be kept short to minimize abrasions from scratching. Coating the affected area with soothing compounds, such as menthol, camphor, chamomile, eucalyptus, and calamine, also can help. Taking antihistamines by mouth may decrease itching. Generally, creams containing antihistamines should not be used, because they can themselves cause an allergic reaction. Corticosteroid creams decrease inflammation and control itching and may be used when itching is


limited to a small area. Itching from some conditions, such as poison ivy, may require highstrength corticosteroid creams. However, only mild corticosteroids, such as 1% hydrocortisone, should be applied to the face and genitals. Oral corticosteroids are sometimes used when large areas of the body are involved. When fungal, parasitic, or bacterial infections cause itching, topical or systemic drugs may be required.

Lice Infestation Lice are barely visible, wingless insects that spread easily from person to person by body contact and shared clothing and other personal items. Head lice infest the scalp hair. The infestation is spread by personal contact and by shared combs, brushes, hats, and other personal items. Head lice are a common scourge of school children of all social strata. Body lice usually infest people who have poor hygiene and those living in close quarters or crowded institutions.

Pubic lice (“crabs”), which infest the genital area, are typically spread during sexual contact. These lice may infest the chest hair, underarm hair, beard hair, eyebrows, and eyelashes as well. Lice infestation causes severe itching in the infested area. Intense scratching often breaks the skin, which can lead to bacterial infections.

Lice themselves are sometimes hard to find, but their eggs are readily apparent. Female lice lay shiny grayish white eggs (nits) that can be seen as tiny globules firmly stuck to hairs near their base. With chronic scalp infestations, the nits grow out with the hair and therefore can be found some distance from the scalp, depending on the duration of the infestation. Topical drugs, in the form of shampoo, cream or liquid, are applied for 10 minutes and then rinsed out. All louse treatments are repeated in seven to 10 days to kill newly hatched lice. After drug application, nits must be removed manually, because drugs do not kill all nits and because it is not possible to distinguish between


living and dead nits. Removal requires a fine-tooth comb – which is often packaged with the medication – and careful searching (hence the term “nit-picking”). Because the nits are so strongly stuck to the hair, several nonprescription preparations are available to loosen them. The nits of body lice are destroyed simply by throwing away infested clothing. Sources of infestation (combs, hats, clothing, and bedding) should be decontaminated by laundering or dry cleaning.

Seborrheic Dermatitis Seborrheic dermatitis occurs most often in infants, usually within the first three months of life, and between the ages of 30 and 70. The disorder is more common in men, often runs in families, and is worse in cold weather. A form of seborrheic dermatitis also occurs in as many as 85 percent of people with AIDS. Seborrheic dermatitis usually begins gradually, causing dry or greasy scaling of the scalp (dandruff), sometimes with itching but without hair loss. In more severe cases, yellowish to reddish scaly pimples appear along the hairline, behind the ears, in the ear

Seborrheic dermatitis occurs most often in infants, usually within the first three months of life, and between the ages of 30 and 70.

canal, on the eyebrows, on the bridge of the nose, around the nose, on the chest, and on the upper back. In infants younger than one month of age, seborrheic dermatitis may produce a thick, yellow, crusted scalp rash (cradle cap) and sometimes yellow scaling behind the ears and red pimples on the face. Frequently, a stubborn diaper rash accompanies the scalp rash. Older children and adults may develop a thick, tenacious, scaly rash with large flakes of skin. The scalp can be treated with a shampoo containing pyrithione zinc, selenium sulfide, an antifungal drug, salicylic acid and sulfur, or tar. The person usually uses the medicated shampoo every other day until the dermatitis is controlled and then twice weekly. In adults, thick crusts and scales, if present, can be loosened with overnight application of corticosteroids or salicylic acid under a shower cap. Often, treatment must be continued for many weeks; if the dermatitis returns after the treatment is discontinued, treatment can be restarted. Topical corticosteroids are also used on the head and other affected areas.

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On the face, only mild corticosteroids, such as 1% hydrocortisone, should be used. Even mild corticosteroids must be used cautiously, because longterm use can thin the skin and cause other problems. In infants and young children who have a thick scaly rash on the scalp, salicylic acid in mineral oil can be rubbed gently into the rash with a soft toothbrush at bedtime.


The scalp can also be shampooed daily with mild baby shampoo, and 1% hydrocortisone cream can be rubbed into the scalp. ■

Information contained in this article comes from The Merck Manuals. For more information, visit skindisorders or search The Merck Manual Home Edition.

Summer Rashes and Bites


Your skin is fair game for bug bites and plant rashes all summer long. Here’s a look at some of these warm weather scourges.

ee stings. Mosquito bites. Poison ivy. During the lazy days of summer, you’re under constant assault from insects and poisonous plants when journeying outdoors. Learn information about these summer problems and how to ease the itch and soothe the sting.


Poison Ivy About 50 to 70 percent of people are sensitive to the plant oil urushiol contained in poison ivy, poison oak, and poison sumac. Once a person has been sensitized by contact with these oils, subsequent exposure produces a contact dermatitis (inflammation of the skin). Symptoms begin from eight to 48 hours after contact and consist of intense itching, a red rash, and multiple blisters, which may be tiny or very large. Typically, the blisters occur in a straight line following the track where the plant brushed along the skin. The rash may appear at different times in different locations either because Want to subscribe to Your Health Now? Log onto

of repeat contact with contaminated clothing and other objects or because some parts of the skin are more sensitive than others. The blister fluid itself is not contagious. The itching and rash last for two to three weeks. Recognition and avoidance of contact with the plants is the best prevention. Washing of the skin with soap and water prevents absorption of the oil if done immediately. Stronger solvents, such as acetone, alcohol, and various commercial products, are probably no more effective. Treatment helps relieve symptoms but does not shorten the duration of the rash. The most effective treatment is with corticosteroids. Small areas of rash are treated with strong topical corticosteroids except on the face and genitals, where only mild corticosteroids, such as 1% hydrocortisone, should be applied. People with large areas of rash or significant facial swelling are given high-dose corticosteroids taken by mouth. Cool compresses wet with water or aluminum acetate may be used on large blistered areas. Antihistamines given by mouth may help with itching.


poison oak

poison sumac

Bee, Wasp, Hornet, and Ant Stings Stings by bees, wasps, and hornets are common throughout the United States. The average person can safely tolerate 10 stings for each pound of body weight. However, one sting can cause death from an anaphylactic reaction (a life-threatening allergic reaction in which blood pressure falls and the airway closes in a person who is allergic to such stings). Bee stings produce immediate pain and a red, swollen area about one-half inch across. In some people, the area swells to a diameter of two inches or more over the next two or three days.

poison ivy

parts of the body. Less common symptoms include backache, nausea and vomiting, sore throat, swollen lymph nodes, and an enlarged spleen. Although most symptoms may come and go, feelings of illness and fatigue may persist for weeks.

The fire ant sting usually produces immediate pain and a red, swollen area, which disappears within 45 minutes. A blister then forms, rupturing in two to three days, and the area often becomes infected. In some cases, a red, swollen, itchy patch develops instead of a blister. Isolated nerves may become inflamed, and seizures may occur. A bee may leave its stinger in the skin. The stinger should be removed as quickly as possible without concern for the method of removal. An ice cube placed over the sting reduces the pain. A cream containing a combination of an antihistamine, an analgesic, and a corticosteroid is often useful. People who are allergic to stings should always carry a preloaded syringe of epinephrine, which blocks anaphylactic or allergic reactions. People who have had a severe allergic reaction to a bee sting sometimes undergo desensitization, which may help prevent future allergic reactions.

Lyme Disease Usually, Lyme disease occurs in the summer and early fall. Children and young adults who live in wooded areas are most often infected. The bacteria that cause Lyme disease are transmitted by the deer tick (Ixodes), so

Lyme disease (erythema migrans)

named because the adult ticks often feed on the blood of deer. The bacteria that cause Lyme disease are transmitted to people when an infected tick bites and stays attached for one or two days. Brief periods of attachment rarely transmit disease. The early-localized stage typically begins with a large, red spot at the site of the bite, usually on the thigh, buttock, trunk, or armpit. The spot (erythema migrans) typically expands to a diameter of six inches (15 centimeters), often with a central clearing (bull’s eye). About 25 percent of infected people never develop – or at least never notice – any red spot. The symptoms of earlydisseminated Lyme disease begin when the bacteria spread through the body from the initial bite area. In this stage, many people feel ill with fatigue, chills and fever, headaches, stiff neck, and aches in muscles and joints. Nearly half develop more, usually smaller, erythema migrans spots on other

deer tick


Abnormalities of nerve function develop in about 15 percent of people. The most common problems are headache, stiff neck, involvement of the tissues covering the brain and spinal cord (aseptic meningitis), and weakness on one side of the face (Bell’s palsy); these may persist months before disappearing. Nerve pain and weakness may develop in other

About 25 percent of infected people never develop – or at least never notice – any red spot.

areas and persist longer. Irregular heartbeats (arrhythmias) and inflammation of the sac around the heart (pericarditis) that causes chest pain develop in eight percent of infected people. In untreated Lyme disease, the late stage begins months to years after the initial infection. Arthritis

develops in about half of the people with late-stage Lyme disease. Episodes of swelling and pain in a few large joints, especially the knee, typically recur for several years. The knees are commonly more swollen than painful, often hot to the touch, and, in rare instances, red. A smaller number of people develop neurologic abnormalities, including problems with speech, memory, mood, and sleep. Sometimes people who develop neurologic abnormalities have numbness or shooting pains in the back, legs, and arms. The most commonly used tests measure antibodies to the bacterium in the blood. However, antibody tests alone are not adequate because they are often negative in the early stages of Lyme disease and are sometimes positive in people who do not have the disease. Most doctors do not give antibiotics to people who were simply bitten by ticks but have no rash or other symptoms. Although all stages of Lyme disease respond to antibiotics, early treatment is the most effective in helping to prevent complications. Treatment is given for three to four weeks. â–

Information contained in this article comes from The Merck Manuals. For more information, visit summerhazards or search The Merck Manual Home Edition.

Preventing Tick and Mosquito Bites Tick Bites The possibility of contact with ticks can be minimized by staying on paths and trails when walking in wooded areas and by not sitting on the ground or on stone walls. Wearing light-colored clothing makes ticks crawling on clothing easier to see. Applying an insecticide containing diethyltoluamide (DEET) to the skin and one containing permethrin to clothing may help protect against tick bites. (Products containing DEET can cause adverse effects and should be used only by closely following the directions on the product labels. The American Academy of Pediatrics recommends that these products not be used in children less than two months old.) People who may have been exposed to ticks should inspect their whole body for ticks daily. Deer ticks, which transmit Lyme disease, are very small, much smaller than dog ticks. So people should check the whole body very carefully, especially hairy areas. Inspection is effective because ticks must be attached for more than a day to transmit Lyme disease. To remove a tick, a person should use fine-pointed tweezers to grasp the tick by the head or mouthparts right where they enter the skin and should pull the tick straight off. The tick’s body should not be grasped or squeezed. Petroleum jelly, alcohol, lit matches, or any other irritants should not be used.

Mosquito Bites Mosquito control measures, which include eliminating breeding areas and killing larvae in the standing water where they live, are very important. People can also limit mosquito exposure by using insecticide sprays in homes and outbuildings, placing screens on doors and windows, using permethrin-impregnated mosquito netting over beds, and applying mosquito repellents containing DEET on exposed areas of the skin. People can wear long pants and long-sleeved shirts, particularly between dusk and dawn, to protect against mosquito bites. People subject to intense mosquito exposure can spray permethrin on their clothing before it is worn. common mosquito


Making Medicine Affordable

continued from page 13

They can simply show their participating discount card when filling their prescriptions and should receive the discount from their card sponsor. Free Merck medicines are available to qualifying low-income seniors who have exhausted their annual Medicare assistance credit, though the dispensing pharmacy may charge a fee. For general information, please call 1-800-MEDICARE or visit There are many other programs available to assist patients.

Looking for answers to your health questions? Visit

The Partnership for Prescription Assistance (PPA) provides a single point of entry to more than 275 public and private patient assistance programs. More information is available at or by calling its toll-free number 1-888-4PPA-Now. The Together Rx Access™ Card is a free program sponsored by several pharmaceutical companies that helps people save up to 40 percent on more than 275 brandname prescription drugs and other prescription products, as well as savings of at least 15 percent on generic prescription medicines. More information can be found at

26 or by calling 1-800-444-4106. Because navigating the many available resources can be difficult, Merck has developed the Guide to Affordable Medicine. This free guide is being provided as a service to the community and will help answer many important questions about these services. To order your free guide, please fill out the business reply card inside this magazine or visit ■

Editor’s Note: Most local libraries offer free access to the Internet.

Identifying the Bumps and Spots on Your Skin

Pet Care, continued from page 20

continued from page 8

Cherry angiomas are overgrowths of blood vessels that form raised red or purple bumps or spots. They are typically no more than one-eighth inch (three millimeters) across. They usually appear on the trunk. Noncancerous skin growths can be removed if they are unattractive or they rub against clothing and become irritated. Usually, they can be removed in a doctor’s office with a scalpel, scissors, liquid nitrogen, or a laser. Sometimes a local anesthetic is used. Some skin growths in older people are cancerous (malignant). That is, they invade other tissues and spread to other parts of the body. Skin should be checked periodically for changes. Certain changes should be reported to a doctor. (For more information, see “The ABCDs of Skin Self-Exams” on page 10). A doctor should thoroughly examine all of the skin once a year to check for new growths or changes in old growths. Sometimes a doctor removes a piece of a growth for examination under a microscope (biopsy). ■ Information contained in this article comes from The Merck Manuals. For more information, visit or search The Merck Manual Home Edition.

the flea life cycle. Fortunately, the modern flea control products available from a veterinarian are long-lasting and effective against both adult fleas and their eggs and larvae.

Beware of Biting Ticks Ticks are small, bloodsucking pests that are most often picked up outdoors, especially in wooded areas. Ticks will bite and burrow their heads into the skin of a host animal, and can remain attached for several days. Several kinds of ticks can bite pets, and many carry infectious organisms that can transmit diseases. For example, deer ticks can transmit the bacteria that causes Lyme disease, which often begins with a circular, flat, red rash after a tick bites and stays attached to the body for one or two days. The disease can cause arthritis, neurological symptoms, fatigue, and vomiting, but is easy to treat if caught early. For more on Lyme disease, see “Summer Rashes and Bites”, page 24. Dog and wood ticks can transmit Rocky Mountain spotted fever, symptoms of which include a rash, abdominal pain, headache, and high fever. The disease occurs mainly from March to September, most commonly in the Midwest and on the Southern Atlantic seaboard, and is potentially fatal;


so those symptoms require urgent medical attention. Ticks are commonly found between the toes of a pet’s paws, behind or inside its ears, or between its legs. Ticks should be removed immediately. Grasp the tick with curved tweezers as close to the skin as possible and pull it directly out. The tick’s head, which may not come out with the body, also should be removed with the tweezers, because it can cause tenderness and swelling. Applying alcohol, fingernail polish, or a hot match are not effective methods and may cause the tick to spit infected saliva into the bite site. Once the tick has been removed, thoroughly clean the area to prevent an infection and spray an indoor insecticide on baseboards and crevices in the walls and floors. Pets that show possible symptoms of a tick-related illness – loss of appetite, weakness, an unsteady walk, vomiting, or fever – should be seen by a veterinarian. Products that are effective against both fleas and ticks are available from the veterinarian. Depending on the area of the country, a pet may need to be treated monthly throughout the year. ■

The contents of this article were adapted from The Merck Veterinary Manual, 9th Edition, published in 2005.

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