Encyclopedia of Health and Medicine

242 The Immune System and Allergies
as a direct action of the substance rather than as a
hypersensitivity reaction.
Treatment Options and Outlook
Treatment may include calamine lotion and cool
baths or compresses to relieve itching in combination
with oral ANTIHISTAMINE MEDICATIONS or CORTI-
COSTEROID MEDICATIONS to interrupt the immune
response. Cool baths or compresses with colloidal
oatmeal can soothe irritated skin. Avoiding further
exposure to the allergen prevents subsequent
reactions and may, over time, allow the immune
response to lessen in severity.
Risk Factors and Preventive Measures
Latex, nickel, chromates, and the dyes in permanent
hair coloring solutions are the most common
causes of allergic dermatitis. Numerous metal
objects, including stainless steel and chrome plating,
contain nickel. Spandex contains latex; spandex
clothing such as undergarments and athletic
wear may cause hypersensitivity reaction in people
who are allergic to latex. Chromates, chemicals
used in tanning leather, are common in
leather shoes, belts, and clothing. The allergen in
permanent hair dyes is a chemical called paraphenylenediamine
(PPDA), which sometimes is
also present in some dyed clothing though is not
commonly used in fabric dyes in the United
States. The risk for allergic dermatitis is particularly
high among people who work in jobs with
constant exposure to these common allergens.
See also ALLERGIC ASTHMA; ALLERGIC CONJUNCTIVI-
TIS; ATOPY; LIVING WITH ALLERGIES; OCCUPATIONAL
HEALTH AND SAFETY; SKIN-ASSOCIATED LYMPHOID TISSUE
(SALT); WHEAL.
allergic rhinitis A HYPERSENSITIVITY REACTION to
inhaled allergens. Allergic rhinitis, also called seasonal
rhinitis or hay FEVER, affects the mucous
membranes inside the NOSE (nasal mucosa). Allergic
rhinitis affects about 40 million adults in the
United States, making it one of the most common
hypersensitivity reactions. The condition tends to
develop in childhood and continue through adulthood,
though some people who have allergic
rhinitis as children seem to outgrow their sensitivities
as they become adults.
MUCOSA-ASSOCIATED LYMPHOID TISSUE (MALT) infiltrates
the nasal mucosa. Within the MALT are
numerous mast cells, the surfaces of which harbor
IMMUNOGLOBULIN E (IgE) antibodies. These antibodies
react within hours to the presence of airborne
allergens such as pollens. Allergic rhinitis is most
common in the spring and the fall, though some
people also experience symptoms in the summer,
depending on what allergies they have. Allergic
rhinitis is primarily a type I (IgE) hypersensitivity
reaction, in which symptoms developing fairly
immediately after contact with the ALLERGEN. The
most common allergens associated with allergic
rhinitis are tree pollens, grass pollens, and weed
pollens. Other potential allergens include dust
mites, pet dander, and other substances that are
continuously present in the environment.
Symptoms and Diagnostic Path
The symptoms of rhinitis range from mild to debilitating.
The classic symptoms occur in response to
the presence of allergens and include
• nasal congestion
• itching
• sneezing
• RHINORRHEA (runny nose)
Some people also develop
• swollen, itchy, reddened eyes (ALLERGIC CON-
JUNCTIVITIS)
• dark circles under the eyes (“allergic shiners”)
• OTITIS media (middle ear INFECTION)
• PHARYNGITIS (sore THROAT) from postnasal drip
(mucus draining down the back of the throat)
• physical irritation of the nose due to frequent
sneezing, blowing, and rubbing
The doctor makes the diagnosis based on the
presentation of symptoms and the person’s
description of how the symptoms develop and
how long they last.
Treatment Options and Outlook
Treatment combines avoiding the allergen when
possible with medications to control symptoms.