Red, bumpy, scaly, itchy, swollen skin-any of these symptoms can signify
an allergic skin condition. These skin problems are often caused by an
immune system reaction, signifying an allergy. Allergic skin conditions can
take several forms and are due to various causes.
Hives and angioedema
Hives or urticaria are red, itchy, swollen areas of the skin that can range
in size and appear anywhere on the body. Approximately 25% of the U.S.
population will experience an episode of hives at least once in their lives.
Most common are acute cases of hives, where the cause is identifiable-often
a viral infection, drug, food or latex. These hives usually go away
spontaneously. Some people have chronic hives that occur almost daily for
months to years. For these individuals, various circumstances or events,
such as scratching, pressure or "nerves," may aggravate their hives.
However, eliminating these triggers has little effect on this condition.
Angioedema, a swelling of the deeper layers of the skin, sometimes occurs
with hives. Angioedema is not red or itchy, and most often occurs in soft
tissue such as the eyelids, mouth or genitals. Hives and angioedema may
appear together or separately on the body. Hives are the result of a
chemical called histamine-responsible for many of the symptoms of allergic
reactions-in the upper layers of the skin. Angioedema results from the
actions of these chemicals in the deeper layers of the skin. These chemicals
are usually stored in our bodies' mast cells, which are cells heavily
involved in allergic reactions. There are several identifiable triggers that
release histamine and other chemicals from the mast cells, causing hives.
In adults, reactions to medicines are a common cause of acute hives.
Medications known to cause hives or angioedema include aspirin and other
non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen, high blood
pressure medicines known as ACE-inhibitors, or pain-killers containing
codeine or codeine-like drugs. Like all drug-induced hives, these reactions
occur within only minutes to an hour of taking the drug. Adults can also
develop hives after eating certain foods, including nuts, eggs, shellfish,
soy, wheat or milk-the culprits in more than 90% of proven food-induced
hives. In children, foods or viral infections such as a cold can trigger
acute hives. Physical urticaria are hives resulting from an outside source:
rubbing of the skin, cold, heat, physical exertion or exercise, pressure or
direct exposure to sunlight. Patients with chronic urticaria often report
that at least one of these triggers induces their hives.
Whenever there is an identifiable trigger of hives, it should be
eliminated. In patients with acute hives, some drugs or foods may take days
to be eliminated from the body. For these individuals, an allergist may
prescribe antihistamines to relieve symptoms until the culprit is
eliminated. For patients with chronic hives, treatment cannot control the
eruptions; these hives will eventually disappear on their own, with or
without treatment. For 50% of these patients, the hives will clear in three
to 12 months; 40% will clear in one to five years. Up to 1.5% of these
patients may experience these hives for more than 20 years. Forty percent of
patients with chronic hives will have at least one more episode of chronic
hives in their lifetime. For these patients, the treatment objective is to
provide comfort. If you experience chronic hives, your allergist will
prescribe antihistamines, and will combine medications and adjust your
dosages as needed for your individual symptoms. In rare cases, if
antihistamines do not provide appropriate comfort, the allergist will
prescribe an oral corticosteroid.
When some substances come into contact with skin, they may cause a rash
called contact dermatitis. Some of these reactions are the result of an
allergic reaction that involves the immune system, but many are the result
of a non-allergic, or irritant, reaction. Often, it is difficult to tell the
difference between these two types of reactions. The hallmark of allergic
contact dermatitis is that it occurs almost exclusively where the offending
agent-such as a plant or chemical-comes in contact with the skin. Irritant
contact dermatitis is often more painful than itchy, and is the result of an
offending agent that actually damages the skin with which it comes into
contact. The longer the skin is in contact-or the more concentrated the
agent-the more severe the reaction. Water with added soaps and detergents is
the most common cause. Thus, it is not surprising that these reactions
appear most often on the hands, and are frequently work-related. Individuals
with other skin diseases, especially eczema (ex-zeh-ma), are most
Allergic contact dermatitis is best exemplified by the itchy, red,
blistered reaction that almost everyone experiences after touching a plant
in the "rhus" family-poison ivy, poison oak or poison sumac. This allergic
reaction is caused by a chemical in the plant called urushiol. You can have
a reaction from touching other items with which the plant has come into
contact, including yard tools or the family dog. However, once your skin has
been washed, you cannot get another reaction from touching the rash or
blisters. Unlike irritant contact dermatitis, which occurs within minutes of
coming into contact with an offending agent, allergic contact dermatitis
reactions can occur 24-48 hours after contact. Once a reaction starts, it
takes 14-28 days to resolve, even with treatment.
Other agents that frequently cause allergic contact dermatitis include
nickel, perfumes and fragrances, dyes, rubber (latex) products and
cosmetics. Some ingredients in medications applied to the skin also can
cause an allergic reaction, most commonly neomycin, an ingredient in
antibiotic creams. To avoid reactions, any cream that ends in "caine" should
never be applied to damaged skin.
Treatment of irritant contact dermatitis requires that the skin be kept
from contact with the agent that is causing the reaction, and that every
precaution is taken to avoid spilling caustic chemicals on the skin. Gloves
can sometimes be helpful. Since these reactions are non-allergic in nature,
treatment is directed toward relieving symptoms and preventing any permanent
damage to the affected skin.
Treatment for allergic contact dermatitis depends on the severity of the
symptoms. Cold soaks and compresses can offer relief for the acute, early,
itchy blistered stage of the rash. When the rash is limited to small areas
of the skin, topical corticosteroid creams may be prescribed to offer
relief. When large areas of the body are involved, oral corticosteroids may
be prescribed. If prescribed, it is important to continue to take oral
medications for the entire duration of the reaction (14-28 days). To prevent
the reaction from recurring, make sure to avoid contact with the offending
substance. If the patient and allergist cannot determine the substance that
caused the reaction based on the patient's history, the allergist may
conduct a series of patch tests to help identify it.
A common allergic reaction often affecting the face, elbows and knees is
atopic dermatitis, also known as eczema. This red, scaly, itchy rash is
usually seen in young infants, but can occur later in life in individuals
with personal or family histories of atopy, meaning asthma or allergic
rhinitis ("hay fever"). Eczema may at times ooze, or at times may look very
dry. A physician will rarely have difficulty diagnosing atopic dermatitis,
based on three factors: an 1) itchy, 2) "eczematous" or bubbly rash in an 3)
atopic individual. If one of these three features is missing, your physician
should consider other causes. Identifying the cause of the itch is essential
in managing symptoms. Common triggers include overheating or sweating, and
contact with irritants such as wool, pets or soaps. In older individuals,
emotional stress can cause a flare-up. For some patients, usually children,
food can also trigger eczema. Secondary staph infections also can cause a
flare-up in children. These patients usually have very dry skin and
"allergic shiners"-an extra crease, called a Dennie's line, across their
lower eyelids. They are also more susceptible to other skin infections.
Preventing the eczema itch is the primary goal of treatment. The patient
must stop scratching and rubbing the rash. Applying cold compresses is
helpful, and lubricating the dry skin with cream or ointment, especially
during dry seasons, is essential. Patients should remove all "irritants"
that aggravate the condition from their environments. If a food is
identified as the culprit, it must be eliminated from the diet.
Topical corticosteroid cream medications are most effective in treating
the rash once all preventative measures are taken. Rarely, antihistamines or
oral corticosteroids are also prescribed, and if a secondary infection has
been introduced by scratching, antibiotics are required.
See your allergist/immunologist
Whenever you have an unusual rash, make sure to contact your allergist, who
will work with you to determine its cause-whether allergies, irritants, or
another trigger. Most importantly, your physician and other health care
providers can offer a support system and assist you in managing your skin
Your allergist/immunologist can provide you with more information on
allergic skin conditions.
Tips to Remember are created by the Public Education Committee
of the American Academy of Allergy, Asthma and Immunology. This brochure was
updated in 2003.
The content of this brochure is for informational purposes only. It is
not intended to replace evaluation by a physician. If you have questions or
medical concerns, please contact your allergist/immunologist.
American Academy of Allergy,
Asthma and Immunology
555 East Wells Street
Milwaukee, WI 53202-3823
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