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Contact Dermatitis


Overview

Contact dermatitis, which is inflammation caused by direct contact with an irritant or allergen, is one of the most common types of skin irritations. It is sometimes referred to as "occupational dermatitis," as it is very common in occupations where individuals come into frequent contact with irritants and allergens. According to data reported by the Centers for Disease Control, the most common manifestation of occupational skin diseases is in fact contact dermatitis (both irritant and allergic).

An inflamed rash will usually first appear on the hands, or wherever the first point of contact with an irritant or allergen occurs. Any area of the skin exposed to an irritant or allergen can be vulnerable to a contact dermatitis rash. Contact dermatitis is not contagious, but a rash can spread from one contaminated area to another on one's own body, for example, when the hands touch other areas of the body. The face is the second most frequently affected area of the body.

Symptoms & causes of contact dermatitis

There are two main types of contact dermatitis, irritant contact dermatitis and allergic contact dermatitis. They are classified based upon the body's reaction to the substance with which it has comes into contact. The symptoms of the two are very similar, though the underlying pathways involved that result in the rash can vary.

Irritant contact dermatitis (ICD) is the most common type of contact dermatitis, responsible for approximately 80% of reported cases. Irritant contact dermatitis occurs as a result of nonspecific irritant factors causing the activation of mainly innate immunity, resulting in skin inflammation. These factors can be found in and on innumerable products and surfaces, but the following are among the more common culprits:

  • Soaps, detergents, solvents (e.g., acetone in nail polish remover) and other "cleaning" chemicals
  • Acids and alkalis (e.g., drain cleaners)
  • Adhesives
  • Fiberglass (commonly found in insulation)
  • Plants (e.g., peppers, poinsettias)
  • Insects (e.g., caterpillars [leptidopterism], including brown tail moth [Euproctis hrysorrhoea (L.)], and processionary caterpillars [Thaumetopoea processionea L., among others])

When the skin comes into contact with the offending mechanical or chemical irritant, a rash may appear in as quickly as a few minutes; or, alternatively, not immediately after first contact but after frequent repeated contacts; or, alternatively, after a prolonged period of exposure.

The rash will appear on the area of the body that first made contact with the chemical, with the hands and forearms being the most frequently affected areas. When the hands are involved it is referred to as irritant hand dermatitis. The severity and persistence of the rash will vary depending upon the individual's skin sensitivity, the concentration of the irritating chemical, the rapid identification of the irritant, and the individual's ability to effectively reduce their exposure.

The condition tends to be more painful than itchy - though not always - and can take on many forms, including redness, dryness, itching, swelling, blistering, crusting, scales, and eventual thickening of skin. In more severe cases, blisters can occur and subsequently open, developing into sores which can become vulnerable to infection.

Allergic contact dermatitis (ACD) is your immune system's adaptive response to an allergenic substance that makes contact with the skin or another region of the body, but which manifests in dermatological inflammation. This type of reaction comprises approximately 20% of the reported cases of contact dermatitis. There are thousands of potential allergens in our environment, but fewer than 30 have been identified as responsible for the large majority of allergic contact dermatitis cases. The more common allergens are:

  • Plants (poison ivy, poison oak, and poison sumac)
  • Insects and other arthropods (e.g., house dust mite, hay itch mite, avian mites, etc.)
  • Fragrances in cosmetics
  • Preservatives
  • Rubber (latex)
  • Antibiotics and other topical drugs
  • Metal ions (e.g., nickel found in jewelry)
  • Pesticides, fertilizers, and other agricultural chemicals

An adaptive immune reaction to an allergen can develop after a single exposure, or it may take many exposures. It's not unusual for an individual to develop a reaction to an allergen even though in the past they've experienced no such reaction. An allergy can appear at any time in one's life. Once the body has developed a dermatological allergy, an immune response triggering dermatitis most often occurs within 4-24 hours following exposure. In older adults, however, a more delayed response time is not unusual, and a rash may not occur for three to four days. Household dust, dust mites, and animal dander as airborne allergens can also exacerbate a dermatologically manifested allergenic response.

Once the rash appears, its characteristics are very similar to those found in irritant contact dermatitis: redness, dryness, itching, swelling, blistering, crusting, scales, and thickening of skin. It is usually confined to the areas that have come into direct contact with the allergen. Again, the hands are usually the first affected areas, with the face being the second most frequently affected region of the body.

Systemic contact dermatitis (SCD) is a third, less common type of contact dermatitis. SCD is characterized by eruptions in the skin following systemic exposure to allergens. In addition to the usual symptoms of contact dermatitis, hives (urticaria) can also develop secondarily as the result of a systemic allergenic response. Exposure to antigens can occur via multiple routes - across the skin, via venous or intramuscular injection, through inhalation or ingestion of airborne allergens (aeroallergens) - to ultimately invoke a systemic flare. Exposure to metals, medications, pollen and other plant parts, to name just a few, can all lead to a systemic allergenic dermatitis

Diagnosis and medical treatment of contact dermatitis

Diagnosing either form of contact dermatitis can be difficult, largely because of the sheer number of irritants and allergens with which an individual may come into contact on a daily basis. A healthcare provider must take into consideration myriad factors, including the type and location of rash; the patient's hobbies, occupation, and daily activities; their use of cosmetics, medications, and detergents; any vacations they may have taken recently; their pets, clothing, and domicile; and anything else that could possibly shed light on how and what the individual may have come into contact with to provoke an inflammatory response of the skin.

If contact dermatitis is suspected but the doctor and patient are unable to determine the irritant or allergen, a skin prick test (SPT) or patch testing may be used. There are several methods of patch testing. One of the most frequently used tests is called the Finn chamber method. With this form of patch testing, a multiwell aluminum patch is filled with the suspected substances and taped to the skin, usually on the patient's upper back. The patch is left on the patient for a 48-hour period and then removed, and an initial reading of the skin is taken. A second reading of the skin is taken a few days later. A second method of patch testing is to apply the suspected substance directly onto the skin with a dressing secured over it. Again, after 48 hours, an initial skin reading is taken and a few days later a second reading is taken. Repeated testing may be needed in order to identify with certainty the correct substance.

Another, more accurate but more involved test known as radioallergosorbent testing (RAST) identifies specific factors in the blood associated with an immune-mediated response to an allergen. RAST is sometimes preferable when an individual wants to know quickly and definitively what may be causing the allergenic response, or when other types of testing produce ambiguous or negative results.

Once the irritant or allergen has been identified treatment centers around preventing future outbreaks by eliminating contact with that substance. Once contact with the allergen or irritant has been ceased the outbreaks will generally also stop. If accidental contact is made, immediate washing of that area with warm soapy water can help prevent or limit a repeat dermatitis flare. Once the substance is removed the remaining rash will often resolve after a week or two, though it may take longer for full resolution of the skin symptoms.

Treatment of an existing rash often involves antihistamine creams, colloidal oatmeal, cold baths, or calamine lotion, and in severe cases a steroidal cream may be prescribed. Steroidal creams are effective in relieving the rash; however, it is important to be aware of the fact that steroids do come with side effects.

Herbal treatments for contact dermatitis

Several all-natural herbal methods can be used to help relieve the pain and itching associated with a contact dermatitis rash. Certain medicinal herbs have antiseptic and anti-inflammatory properties, which can help to relieve the symptoms associated with a contact dermatitis. Below are a few of the botanical extracts that are sometimes used to allay inflammatory symptoms.

  • Calendula (flower heads), licorice root, and ginkgo all have antiseptic and anti-inflammatory properties. They can be used topically in lotions, oils or ointment form, and applied directly to the affected area to reduce itching and inflammation and diminish risk of secondary infection.
  • Aloe vera gel and the juice from the leaves of common plantain (Plantago officinalis) can be applied topically to the affected areas to help soothe skin irritations associated with dermatitis.

There are also a number of herbal "packs," "plasters," or "pastes" that can be prepared to help relive the itching associated with contact dermatitis.

  • Green clay and goldenseal root in equal parts
  • Equal parts salt, water, clay, and peppermint oil
  • Calamine lotion
  • Coal tar lotions, shampoos, or bath oils

Pyrithione zinc treatment

For centuries pyrithione zinc has been recognized for its unique healing properties, a number of which have been proven helpful in alleviating dermatitis symptoms.

Pyrithione zinc is an antiseborrheic, which means that it helps to prevent or relieve excessive secretions of the sebaceous glands. These glands lie beneath the skin and they work to soften and lubricate the skin and hair. When they become overactive, like during an outbreak of dermatitis, the skin will become inflamed and irritated. Therefore pyrithione zinc's ability to limit these outbreaks helps to reduce the flare-ups of atopic dermatitis.

Pyrithione zinc also has antifungal and antibacterial properties, which may help reduce secondary infection associated with skin inflammation. Topical zinc pyrithione is generally recognized as a safe and effective treatment for reduction in the symptoms associated with dermatitis.


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bookContact Dermatitis—Reference Documents and Further Reading



Principal Authors: DermaHarmony Editorial Staff
Date of Publication: 04/10/2008
Updated: 06/07/2011