What Is It?
A rash is a
temporary eruption or discoloration of the skin that is
often inflamed or swollen. Rashes come in many forms and
levels of severity, and they last for different periods.
Some common causes of rashes include:
Infections This broad category covers a wide range of
illnesses, such as: viral infections (such as measles,
rubella, roseola, fifth disease, varicella zoster or
shingles); bacterial infections (such as impetigo,
scarlet fever, Lyme disease; fungal infections, and
reactions These can be triggered by: medications
(including antibiotics, seizure medications and
diuretics); topical skin products (such as cosmetics,
perfumes, skin creams); foods (especially peanuts,
seafood, eggs); or insect stings (including bees, wasps,
irritants This category includes diaper rash (caused
by prolonged skin contact with urine and stool) and
rashes caused by contact with harsh chemicals (such as
laundry soaps, fabric softeners).
exposure Poison ivy, poison oak and poison sumac share
a highly allergenic sap resin that can cause allergic
rashes in 70 percent of people exposed to it.
- Autoimmune disorders This category includes systemic
scleroderma, disorders in
which the body's immune defenses mistakenly attack
healthy areas of the body, including the skin.
is easily recognized, all rashes are not the same. Rashes
vary in their appearance, timing, location or
distribution, and duration. In general, rashes may be
described as macular (showing flat, red spots),
papular (showing small, raised, solid bumps),
macular and papular (a combination of macules and
papules), papulosquamous (a combination of papules
and scaly areas), and vesicular (showing small,
raised, fluid-filled blisters).
signs and symptoms that sometimes accompany rashes
lymph nodes (swollen glands)
- Signs of a severe allergic, potentially life-threatening
reaction requiring immediate emergency medical
attention: difficulty breathing,
hives, vomiting, abdominal
cramps, rapid drop in blood pressure, confusion,
- Signs of an autoimmune disorder, such as
lupus (may include fatigue,
poor appetite, fever, joint swelling) or
includes weak muscles, swelling and violet discoloration
of the eyelids, difficulty rising after sitting)
will take a thorough medical history, including your
history of allergies and your work history (a check for
exposure to chemical irritants or to patients with
infections). Your doctor also may ask specific questions
about your rash, including:
Did it appear after you ate a new food, tried a
new skin care product or took a new medication?
Location and pattern Does the rash affect only
sun-exposed areas, or only areas in direct contact with
gloves, shoes, goggles or face masks (as would be
expected with allergic reactions to a chemical in the
item)? Does it form a "butterfly" pattern over the
cheeks and nose (a classic sign of lupus), or does it
produce a bright red "slapped cheek" pattern (a sign of
fifth disease)? Does it form linear streaks along the
lower legs of a hiker (a sign of poison ivy)?
Duration Did the rash appear and disappear within
a day or two (as in roseola), or has it lasted for a
week (as in fifth disease) or longer (as in SLE).
Occupational exposures Is the patient a day-care
worker who may be exposed to children with
rash-producing illnesses (measles, rubella, roseola,
fifth disease)? Does the patient work or play near
wooded areas where there is increased risk of tick
The doctor may
suspect a specific cause for your rash based on your
medical history and the history of your rash. During the
physical examination, your doctor will have the
opportunity to confirm these suspicions by evaluating the
rash's appearance, location, pattern and any associated
symptoms. In many cases, the results of your physical
examination will clarify the diagnosis, and no further
tests will be needed.
additional testing is required, this may include:
testing Although most viral exanthems, or rashes,
do not require specific identification of the virus,
blood tests are available to identify some viruses and
bacteria that cause rash-producing infections. Blood
tests also may be performed to check for autoimmune
tests If your doctor suspects a local allergic
reaction, he or she may conduct skin tests called patch
tests. In these tests, tiny amounts of various chemicals
are placed on your skin for two days. An allergic rash
is looked for when the patch is removed, or one to two
Wood's light A Wood's lamp is a black light used
to aid in evaluating rashes. Depending on the specific
reason for the rash, the light may cause the affected
area of skin to glow red, pale blue, yellow or white.
Tzanck smear In this test, a blister is opened and
scraped to obtain a laboratory sample that is checked
for signs of herpes virus infection.
preparation In this test, a skin area that is
suspected of having a fungal infection is gently
scraped. Scraped material is placed on a slide and
treated with KOH (potassium hydroxide) and examined
under the microscope for signs of fungi.
biopsy In this procedure, the skin is numbed and a
sample of affected skin is removed and examined in the
laboratory. Stitches may be required.
duration of a rash depends on its cause, most rashes
usually disappear within a few days. For example, the rash
of a roseola viral infection usually lasts one to two
days, whereas the rash of measles disappears within six to
seven days. Rashes due to an antibiotic allergy may last
three to 14 days, whereas diaper rash almost always clears
up within one week (if diapers are changed frequently).
Rashes due to
lupus or dermatomyositis may persist for an extended
period of time.
depends on the cause of the rash:
Infections Check that you and your children are
up-to-date in your schedule of routine immunizations.
Practice frequent handwashing, bathe regularly, and
avoid sharing clothing or personal grooming items with
other people. To prevent Lyme disease, wear
light-colored clothing that contrasts with the poppy
seedlike tick and covers most of your skin when you go
into the woods, use approved tick repellents, and ask
your doctor about your need for the newly approved Lyme
immunization. Be aware that you are at an increased risk
of tick exposure in areas of the country where Lyme
disease is common.
Allergic reactions Avoid the specific food,
medicine, skin-care products or cosmetics that you have
had a reaction to. Never take a medicine prescribed for
Irritants For diaper rash, change diapers as soon
as they become wet or soiled. Make sure that your baby's
bottom is completely clean and dry before closing up the
fresh diaper. For sensitivity to chemicals in cleaning
products, switch to laundry soaps and fabric softeners
that are free of dyes and perfumes. For irritation due
to cosmetics, use hypoallergenic products that contain
fewer skin-irritating preservatives and fragrances.
Poisonous plants Learn to recognize poison ivy,
poison oak and poison sumac. When you hike in the woods
or do yard work, cover exposed arms and legs with
long-sleeved shirts and long pants.
Insect stings If you suspect that you are allergic
to insect stings, see an allergist for testing and
possible desensitization therapy. Ask your doctor about
your need for a bee-sting kit, which contains emergency
medication to prevent potentially life-threatening
depends on the cause of the rash:
Infections Bacterial infections are treated with
antibiotics, whereas fungal infections are treated with
antifungal medications. Many viral infections that cause
rash will resolve within several days and require no
medication; less often, antiviral drugs are necessary.
Avoidance when when prolonged exposure to Aspergillus.
Allergic reactions A severe allergic reaction is a
life-threatening medical emergency. It must be treated
immediately with epinephrine, a medication that opens
narrowed airways and raises dangerously low blood
pressure. Localized allergic reactions can be treated
with hydrocortisone cream, antihistamines and ice to
relieve the itching and swelling.
Irritants Diaper rash is treated with good diaper
hygiene (frequent changing of soiled diapers) together
with nonprescription creams or ointments that contain
zinc oxide and mineral oil.
Prickly heat For heat rashes caused by prolonged
heat exposure, nonprescription lotions may be applied to
the skin. For severe symptoms, your doctor may prescribe
steroid medications to relieve discomfort and
Poisonous plants The skin should be thoroughly
flushed with warm water to remove the oil soluble
allergenic substance. Only then should you lather with
soap and water. If you immediately take a bar of soap to
your skin before flushing the skin with water, you are
apt to spread the allergenic plant oil over your skin.
Once you have washed off the oil, it cannot spread. The
allergic dermatitis is usually treated with prescription
topical steroids; however, oral steroids maybe needed
for extensive rashes.
Autoimmune disorders These illnesses are treated
with corticosteroid and immunosuppressive drugs
medications that suppress the patient's overactive
Call A Professional
Seek immediate medical attention if
you begin to have difficulty breathing or develop hives, a
fever, a fast pulse, confusion or nausea. These could be
signs of a
life-threatening allergic reaction.
your doctor promptly if the rash:
beyond one week
signs of local infection (oozing, redness or swelling of
together with fever, chills, swollen glands or other
symptoms of infection (sore throat, cough, headache,
nasal congestion, etc.)
together with symptoms that suggest an autoimmune
disorder, such as recurring fever, malaise, fatigue,
unexplained weight loss and joint swelling
the prognosis for most rashes is excellent, especially
after the cause has been accurately identified.
allergic reactions, the patient can die within minutes
without immediate medical treatment. With proper
treatment, complete recovery usually occurs.
Unfortunately, the patient remains at risk for future
severe reactions if he is exposed to the same
allergy-producing agent. For this reason, a prescription
for an epinephrine-containing, self-injection pen for
emergencies is usually recommended.
autoimmune conditions rash is only one of a wide variety
of symptoms. The prognosis depends on the type and
severity of the autoimmune disease.
information about rashes, you can contact:
National Institute of Arthritis
and Musculoskeletal and Skin Diseases Information
1 AMS Circle
Bethesda, MD 20892-3675
Phone: (301) 495-4484
Toll Free: (877) 226-4267
Fax: (301) 718-6366
TTY: (301) 565-2966
American Academy of Dermatology
930 North Meacham Rd.
Shaumburg, IL 60173
Phone: (847) 330-0230
Toll-free: (888) 462-3376
American Academy of Allergy,
Asthma, and Immunology (AAAAI)
611 East Wells St.
Milwaukee, WI 53202
Toll-free (800) 822-2762
Food Allergy Network, The
10400 Eaton Place
Fairfax, VA 22030
Toll-free: (800) 929-4040
Fax: (703) 691-2713
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