Contact with everyday objects — from
shampoo and jewelry to food and water — causes this very common type
of eczema. When the contact leads to irritated skin, the eczema is
called irritant contact dermatitis. If an allergic reaction
develops on the skin after exposure, the eczema is called
allergic contact dermatitis.
A case of
irritant contact dermatitis caused by frequently handling
This woman develops allergic
contact dermatitis when nickel, often found in jewelry,
touches her skin.
with permission of the American Academy of
National Library of Dermatologic Teaching Slides)
Signs and Symptoms
Allergic contact dermatitis usually develops a few hours
after the allergen (substance to which the person is allergic)
touches the skin and causes:
Itchy, swollen, and red skin or dry
and bumpy skin
Blisters may develop if the reaction
is more severe
Blisters may break, leaving crusts
Skin may later flake and crack
With long-term exposure to an
allergen, the skin becomes thick, red, and scaly. Over time, the
skin can darken and become leathery.
Irritant contact dermatitis
occurs after frequent exposure to a mild irritant, such as
detergent, and after brief exposure to a strong irritant, such as
battery acid. Signs and symptoms of irritant contact dermatitis
Mild irritant – Begins with dry,
chapped skin. With repeat exposure, patches of itchy, red, scaly,
and swollen skin develop. The skin may burn or sting upon contact.
If exposure continues, the skin tends to crack, scale, and become
excessive dry. Sores and blisters may develop that later erupt,
forming crusts and scales.
Strong irritant – Upon contact, the
skin may burn, sting, and/or itch. Redness, swelling, blistering
usually develop. Later, scale may form.
Once irritant contact dermatitis
develops, exposure to mild substances, such as baby shampoo and even
water, can irritate the skin and make the condition worse.
Anyone can develop irritant
contact dermatitis with sufficient exposure to something that
damages the skin and causes irritation.
Allergic contact dermatitis
occurs when someone develops an allergy to a something that
touches the skin.
Allergic contact dermatitis. More than 3,000 allergens
(substance to which the person is allergic) are known to cause
allergic contact dermatitis. Common allergens include:
Ingredients in over-the-counter topical antibiotic ointments
frequently cause an allergic skin reaction.
Clothing and shoes. The
leather, glue, or rubber in one’s shoes can cause allergic contact
dermatitis as can dyes and fire retardants used in clothing.
Concrete. Often the cause of
chronic hand dermatitis, a reaction to concrete can persist long
after the exposure ends.
Fragrances. Found in perfumes,
makeup, as well as skin and hair care products, fragrances
commonly cause an allergic reaction. Even products labeled
“unscented” can cause a reaction because unscented does not mean
the product does not contain fragrance; it means the fragrance is
masked. Look for products labeled “fragrance free.”
Metals. Metals occur in
everyday objects that we touch and in our food. Nickel, one of the
most common metals that causes an allergic reaction, is found in
jewelry and many foods, including tomatoes, chocolate, nuts, and
soy. Mercury (used in dental fillings), gold, cobalt, and chromate
(used to tan leather) are other metals that frequently cause
allergic contact dermatitis.
Plants. A brush with poison
ivy, poison oak, or poison sumac is a frequent cause.
Rubber accelerators. Found in
everything from mouse pads to gym equipment, these allergens can
be difficult to find.
Sometimes allergic contact dermatitis
does not flare until it is triggered. Ultraviolet (UV) light and
perspiration can trigger allergic contact dermatitis.
Exposure to ultraviolet (UV) light.
The rash may not develop until triggered by exposure to sunlight
or another source of UV light, such as a tanning bed. Called
photoallergy, this form of allergic contact dermatitis occurs
when an everyday product, such as a fragrance or sunscreen, is
applied to the skin and then exposed to UV light. Some medications
also can cause a photoallergic reaction.
Perspiration. This may trigger
a flare-up. For example, some people who develop an allergy to
nickel may not have a flare-up when nickel touches their skin
unless they perspire.
Irritant contact dermatitis.
When a substance damages the skin faster than the skin can repair
itself, irritant contact dermatitis develops. Substances that
frequently cause irritant contact dermatitis include water, soaps,
detergents, cleaners, fiberglass, hair dyes, solvents, oils, paints,
varnishes, foods, and metalworking fluids.
Medical history. While anyone
can develop irritant contact dermatitis, having a history of
atopic dermatitis, allergic contact dermatitis, or psoriasis
increases the risk. Pre-existing hand dermatitis also increases
Age. Younger individuals are
more susceptible to allergic contact dermatitis because the immune
system of a younger person is more likely to overreact than the
immune system of an older person.
Repeat exposure. The first
exposure does not always result in an outbreak. With allergic
contact dermatitis, the person’s skin often touches the allergen
for many years before a reaction develops. Mild irritants, such as
detergent, fish scales, and garlic, require frequent exposure to
cause irritant contact dermatitis.
Occupation. People who work in
certain occupations have a much higher risk of developing contact
dermatitis. Health care workers, hairdressers, people who handle
food, bartenders, janitors, and mechanics — to name a few — have
an increased risk.
Gender. Females tend to have a
slightly higher risk of developing contact dermatitis.
Environment. Extreme heat and
cold as well as very humid and very dry environments increase the
When the responsible allergen or irritant no longer touches the
skin, the skin can clear. If the responsible substance(s) continues
to touch the skin, contact dermatitis can become severe and
difficult to treat.
Diagnosis begins with a complete
medical history and examination of the skin.
If the dermatologist suspects
allergic contact dermatitis, a safe and effective test called
patch testing can help identify the allergen(s). During a
patch test, strips of tape that contain small amounts of several
possible allergens, usually 25 to 150, are applied to the
patient’s back. The amounts are too small to cause a reaction
unless the person is allergic. After 2 days, the patient returns,
and the tape is removed. If a small red spot appears, the
substance is considered a possible allergen. After 96 hours, the
patient is checked again to see if any delayed reactions occur.
Irritants cannot be identified via
testing. To identify irritants, a dermatologist must ask
Avoiding the substance(s) causing
the irritation or allergy. The patient must avoid the cause.
Avoiding all substances that can trigger a flare-up can be
difficult — if not impossible — when the person encounters these
substances in the workplace. Dermatologists usually help their
patients develop a strategy to circumvent exposure. This may
include using a barrier cream, wearing gloves, and practicing
Therapy to help clear the skin.
Treatment may include applying emollients and moisturizers
frequently throughout the day, taking an oral antihistamine to
help stop the itch, and applying a topical corticosteroid or
calcineurin inhibitor to reduce inflammation. In more severe
cases, phototherapy treatments may be used to suppress the
person’s overactive immune response. If an infection develops,
antibiotics are necessary.
If contact dermatitis persists despite treatment, oral or
injectable corticosteroids can be used for a short time to get the
inflammation under control.
Once the contact dermatitis clears, the
patient must continue to avoid the identified allergens — and
sometimes irritants. For example, patients who develop an allergic
reaction when nickel touches their skin need to avoid jewelry that
contains nickel as well as many foods, including canned goods,
tomatoes, and chocolate. A dermatologist can help the patient devise
a strategy for avoiding known allergens.
Belsito D et al. “A prospective randomized clinical trial of 0.1%
tacrolimus ointment in a model of chronic allergic contact
dermatitis.” Journal of the American Academy of Dermatology.
Cohen DE et al. “Contact and Occupational Dermatology.” Presented as
a course at: The 63rd Annual Meeting of the American Academy of
Dermatology. February 2005; New Orleans.
Ehrlich A. “Fragrance Allergy.” Presented as a focus session at: The
American Academy of Dermatology’s ACADEMY ’06 Summer Meeting. July
2006; San Diego.
Fowler JF et al. “Contact Dermatitis.” Presented as a forum at: The
64th Annual Meeting of the American Academy of Dermatology. March
2006; San Francisco.
The Lewin Group (prepared for the Society for Investigative
Dermatology and the American Academy of Dermatology Association).
“The Burden of Skin Diseases.” 2004. p. 37-40.
Perryman JH et al. “A Patch Test Study to Evaluate the Allergenicity
of a Metallic Jewelry Alloy in Patients Allergic to Cobalt.”
Cutis. 2006 February;77(2):77-80.
Zug KA et al. “Contact and Occupational
Dermatitis.” Presented as a symposium at: The 64th Annual Meeting of
the American Academy of Dermatology. March 2006; San Francisco.
All content solely
developed by the American Academy of Dermatology
With repeat exposure,
thousands of things that we frequently touch can
irritate our skin. The list includes:
Adhesives and glues
Bacteria and fungi
Bleaches, detergents, and polishes
Hair dyes and shampoos
Metals – nickel, mercury, zinc, and others
Oils and greases
Tar and asphalt