Contact dermatitis

Contact dermatitis

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Encyclopedia
Contact dermatitis is a term for a skin
Skin
-Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...

 reaction (dermatitis
Dermatitis
-Etymology:Dermatitis derives from Greek derma "skin" + -itis "inflammation" and genetic disorder.-Terminology:There are several different types of dermatitis. The different kinds usually have in common an allergic reaction to specific allergens. The term may describe eczema, which is also called...

) resulting from exposure to allergens (allergic contact dermatitis
Allergic contact dermatitis
Allergic contact dermatitis is a form of contact dermatitis that is the manifestation of an allergic response caused by contact with a substance....

) or irritants
Irritation
Irritation or exacerbation, in biology and physiology, is a state of inflammation or painful reaction to allergy or cell-lining damage. A stimulus or agent which induces the state of irritation is an irritant...

 (irritant contact dermatitis
Irritant contact dermatitis
Irritant contact dermatitis is a form of contact dermatitis that can be divided into forms caused by chemical irritants and those caused by physical irritants.-Chemical irritant contact dermatitis:...

). Phototoxic
Phototoxic
Phototoxicity is a chemically induced skin irritation requiring light . The skin response resembles an exaggerated sunburn. The involved chemical may enter into the skin by topical administration or it may reach the skin via systemic circulation following ingestion or parenteral administration...

 dermatitis occurs when the allergen or irritant is activated by sunlight.

Symptoms


Contact dermatitis is a localized rash or irritation of the skin caused by contact with a foreign substance. Only the superficial regions of the skin are affected in contact dermatitis. Inflammation of the affected tissue is present in the epidermis (the outermost layer of skin) and the outer dermis
Dermis
The dermis is a layer of skin between the epidermis and subcutaneous tissues, and is composed of two layers, the papillary and reticular dermis...

 (the layer beneath the epidermis). Unlike contact urticaria
Urticaria
Urticaria is a kind of skin rash notable for pale red, raised, itchy bumps. Hives is frequently caused by allergic reactions; however, there are many non-allergic causes...

, in which a rash appears within minutes of exposure and fades away within minutes to hours, contact dermatitis takes days to fade away. Even then, contact dermatitis fades only if the skin no longer comes in contact with the allergen or irritant. Contact dermatitis results in large, burning, and itchy rashes, and these can take anywhere from several days to weeks to heal. Chronic contact dermatitis can develop when the removal of the offending agent no longer provides expected relief.

Causes


In North and South America, the most common causes of allergic contact dermatitis are plants of the Toxicodendron
Toxicodendron
Toxicodendron a genus of flowering plants in the sumac family, Anacardiaceae. It contains woody trees, shrubs and vines, including poison ivy, poison oak, and the lacquer tree. All members of the genus produce the skin-irritating oil urushiol, which can cause a severe allergic reaction...

 genus: poison ivy
Poison ivy
Toxicodendron radicans, better known as poison ivy , is a poisonous North American plant that is well known for its production of urushiol, a clear liquid compound found within the sap of the plant that causes an itching rash in most people who touch it...

, poison oak
Western Poison-oak
Toxicodendron diversilobum, western poison oak or Pacific poison-oak is in the Anacardiaceae family and is a plant best known for its ability to cause allergic rashes after contact...

, and poison sumac
Poison Sumac
Poison sumac is a woody shrub or small tree growing to 7 m tall. All parts of the plant contain a resin called urushiol that causes skin and mucous membrane irritation to humans...

. Specific plant species that can induce such contact dermatitis include Western Poison Oak, a widespread plant in the western USA. Common causes of irritant contact dermatitis are harsh (highly alkaline) soaps, detergents, and cleaning products.

Types


There are three types of contact dermatitis: irritant contact dermatitis
Irritant contact dermatitis
Irritant contact dermatitis is a form of contact dermatitis that can be divided into forms caused by chemical irritants and those caused by physical irritants.-Chemical irritant contact dermatitis:...

, allergic contact dermatitis
Allergic contact dermatitis
Allergic contact dermatitis is a form of contact dermatitis that is the manifestation of an allergic response caused by contact with a substance....

, and photocontact dermatitis. Photocontact dermatitis is divided into two categories that is, phototoxic and photoallergic.

Irritant contact dermatitis



Irritant contact dermatitis can be divided into forms caused by chemical irritants and those caused by physical irritants. Common chemical irritants implicated include solvents (alcohol, xylene
Xylene
Xylene encompasses three isomers of dimethylbenzene. The isomers are distinguished by the designations ortho- , meta- , and para- , which specify to which carbon atoms the two methyl groups are attached...

, turpentine
Turpentine
Turpentine is a fluid obtained by the distillation of resin obtained from trees, mainly pine trees. It is composed of terpenes, mainly the monoterpenes alpha-pinene and beta-pinene...

, esters, acetone
Acetone
Acetone is the organic compound with the formula 2CO, a colorless, mobile, flammable liquid, the simplest example of the ketones.Acetone is miscible with water and serves as an important solvent in its own right, typically as the solvent of choice for cleaning purposes in the laboratory...

, ketones, and others); metalworking fluids (neat oils, water-based metalworking fluids with surfactants); latex; kerosene
Kerosene
Kerosene, sometimes spelled kerosine in scientific and industrial usage, also known as paraffin or paraffin oil in the United Kingdom, Hong Kong, Ireland and South Africa, is a combustible hydrocarbon liquid. The name is derived from Greek keros...

; ethylene oxide
Ethylene oxide
Ethylene oxide, also called oxirane, is the organic compound with the formula . It is a cyclic ether. This means that it is composed of two alkyl groups attached to an oxygen atom in a cyclic shape . This colorless flammable gas with a faintly sweet odor is the simplest epoxide, a three-membered...

; surfactants in topical medications and cosmetics (sodium lauryl sulfate); alkalies (drain cleaners, strong soap with lye
Lye
Lye is a corrosive alkaline substance, commonly sodium hydroxide or historically potassium hydroxide . Previously, lye was among the many different alkalis leached from hardwood ashes...

 residues). Physical irritant contact dermatitis may most commonly be caused by low humidity from air conditioning
Air conditioning
An air conditioner is a home appliance, system, or mechanism designed to dehumidify and extract heat from an area. The cooling is done using a simple refrigeration cycle...

. Also, many plant
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...

s directly irritate the skin.

Allergic contact dermatitis



Although less common than ICD, ACD is accepted to be the most prevalent form of immunotoxicity found in humans. By its allergic nature, this form of contact dermatitis is a hypersensitive
Hypersensitivity
Hypersensitivity refers to undesirable reactions produced by the normal immune system, including allergies and autoimmunity. These reactions may be damaging, uncomfortable, or occasionally fatal. Hypersensitivity reactions require a pre-sensitized state of the host. The four-group classification...

 reaction that is atypical within the population. The mechanisms by which these reactions occur are complex, with many levels of fine control. Their immunology centres around the interaction of immunoregulatory cytokines and discrete subpopulations of T lymphocytes. Allergens include nickel
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...

, gold
Gold
Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...

, balsam of Peru (Myroxylon
Myroxylon
Myroxylon J.R.Forst. & G.Forst is a synonym of Xylosma.Myroxylon is a genus of two species of Central American and South American trees in the Fabaceae . The tree is well known in the western world as the source for Peru balsam and Tolu balsam. The tree is often called Quina or Balsamo...

 pereirae), chromium
Chromium
Chromium is a chemical element which has the symbol Cr and atomic number 24. It is the first element in Group 6. It is a steely-gray, lustrous, hard metal that takes a high polish and has a high melting point. It is also odorless, tasteless, and malleable...

 and the oily coating from plants of the Toxicodendron
Toxicodendron
Toxicodendron a genus of flowering plants in the sumac family, Anacardiaceae. It contains woody trees, shrubs and vines, including poison ivy, poison oak, and the lacquer tree. All members of the genus produce the skin-irritating oil urushiol, which can cause a severe allergic reaction...

 genus: poison ivy
Poison ivy
Toxicodendron radicans, better known as poison ivy , is a poisonous North American plant that is well known for its production of urushiol, a clear liquid compound found within the sap of the plant that causes an itching rash in most people who touch it...

, poison oak
Western Poison-oak
Toxicodendron diversilobum, western poison oak or Pacific poison-oak is in the Anacardiaceae family and is a plant best known for its ability to cause allergic rashes after contact...

, and poison sumac
Poison Sumac
Poison sumac is a woody shrub or small tree growing to 7 m tall. All parts of the plant contain a resin called urushiol that causes skin and mucous membrane irritation to humans...

.

Photocontact dermatitis


Sometimes termed "photoaggravated", and divided into two categories, phototoxic and photoallergic, PCD is the eczematous condition which is triggered by an interaction between an otherwise unharmful or less harmful substance on the skin and ultraviolet light (320-400 nm UVA) (ESCD 2006), therefore manifesting itself only in regions where the sufferer has been exposed to such rays. Without the presence of these rays, the photosensitiser is not harmful. For this reason, this form of contact dermatitis is usually associated only with areas of skin which are left uncovered by clothing, and it can be soundly defeated by avoiding exposure to sunlight. The mechanism of action varies from toxin to toxin, but is usually due to the production of a photoproduct. Toxins which are associated with PCD include the psoralens. Psoralens are in fact used therapeutically for the treatment of psoriasis, eczema and vitiligo.

Photocontact dermatitis is another condition where the distinction between forms of contact dermatitis is not clear cut. Immunological mechanisms can also play a part, causing a response similar to ACD.

Symptoms


Allergic dermatitis is usually confined to the area where the trigger actually touched the skin, whereas irritant dermatitis may be more widespread on the skin. Symptoms of both forms include the following:
  • Red rash
    Rash
    A rash is a change of the skin which affects its color, appearance or texture. A rash may be localized in one part of the body, or affect all the skin. Rashes may cause the skin to change color, itch, become warm, bumpy, chapped, dry, cracked or blistered, swell and may be painful. The causes, and...

    . This is the usual reaction. The rash appears immediately in irritant contact dermatitis; in allergic contact dermatitis, the rash sometimes does not appear until 24–72 hours after exposure to the allergen.
  • Blisters or wheals. Blisters, wheal
    Wheal
    Wheal may refer to:*Wheal response, a cutaneous condition left by a blow or as part of an allergic reaction*Wheal, a Cornish mine...

    s (welts), and urticaria
    Urticaria
    Urticaria is a kind of skin rash notable for pale red, raised, itchy bumps. Hives is frequently caused by allergic reactions; however, there are many non-allergic causes...

     (hives) often form in a pattern where skin was directly exposed to the allergen or irritant.
  • Itchy, burning skin. Irritant contact dermatitis tends to be more painful than itchy, while allergic contact dermatitis often itches.


While either form of contact dermatitis can affect any part of the body, irritant contact dermatitis often affects the hands, which have been exposed by resting in or dipping into a container (sink, pail, tub, swimming pools with high chlorine) containing the irritant.

Self-care at home

  • Immediately after exposure to a known allergen or irritant, wash with soap and cool water to remove or inactivate most of the offending substance.
  • Weak acid solutions [lemon juice, vinegar] can be used to counteract the effects of dermatitis contracted by exposure to basic
    Base (chemistry)
    For the term in genetics, see base A base in chemistry is a substance that can accept hydrogen ions or more generally, donate electron pairs. A soluble base is referred to as an alkali if it contains and releases hydroxide ions quantitatively...

     irritants.
  • If blistering develops, cold moist compresses applied for 30 minutes 3 times a day can offer relief.
  • Calamine lotion and cool colloidal oatmeal baths may relieve itching.
  • Oral antihistamines such as diphenhydramine
    Diphenhydramine
    Diphenhydramine hydrochloride is a first-generation antihistamine possessing anticholinergic, antitussive, antiemetic, and sedative properties which is mainly used to treat allergies. Like most other first-generation antihistamines, the drug also has a powerful hypnotic effect, and for this reason...

     (Benadryl, Ben-Allergin) can also relieve itching.
  • For mild cases that cover a relatively small area, hydrocortisone cream in nonprescription strength may be sufficient.
  • Avoid scratching, as this can cause secondary infections.
  • A barrier cream
    Barrier cream
    A barrier cream is a topical formulation used in industrial and medical environments to place a physical barrier between the skin and contaminants which may irritate the skin and cause contact dermatitis or occupational dermatitis.- Medical application :...

     such as those containing zinc oxide
    Zinc oxide
    Zinc oxide is an inorganic compound with the formula ZnO. It is a white powder that is insoluble in water. The powder is widely used as an additive into numerous materials and products including plastics, ceramics, glass, cement, rubber , lubricants, paints, ointments, adhesives, sealants,...

     (e.g. Desitin, etc.) may help to protect the skin and retain moisture.

Medical care


If the rash does not improve or continues to spread after 2-3 of days of self-care, or if the itching and/or pain is severe, the patient should contact a dermatologist or other physician
Physician
A physician is a health care provider who practices the profession of medicine, which is concerned with promoting, maintaining or restoring human health through the study, diagnosis, and treatment of disease, injury and other physical and mental impairments...

 or physician assistant. Medical treatment usually consists of lotions, creams, or oral medications.
  • Corticosteroids. A corticosteroid
    Corticosteroid
    Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex. Corticosteroids are involved in a wide range of physiologic systems such as stress response, immune response and regulation of inflammation, carbohydrate metabolism, protein catabolism, blood electrolyte...

     medication similar to hydrocortisone may be prescribed to combat inflammation in a localized area. This medication may be applied to your skin as a cream or ointment. If the reaction covers a relatively large portion of the skin or is severe, a corticosteroid in pill or injection form may be prescribed.
  • Antihistamines. Prescription antihistamines may be given if nonprescription strengths are inadequate.

Prevention


Since contact dermatitis relies on an irritant or an allergen to initiate the reaction, it is important for the patient to identify the responsible agent and avoid it. This can be accomplished by having patch tests, a method commonly known as allergy testing. The patient must know where the irritant or allergen is found to be able to avoid it. It is important to also note that chemicals sometimes have several different names.

In an industrial setting the employer has a duty of care to the individual worker to provide the correct level of safety equipment to mitigate the exposure to harmful irritants. This can take the form of protective clothing, gloves or barrier cream
Barrier cream
A barrier cream is a topical formulation used in industrial and medical environments to place a physical barrier between the skin and contaminants which may irritate the skin and cause contact dermatitis or occupational dermatitis.- Medical application :...

 depending on the working environment.

Summary


The distinction between the various types of contact dermatitis is based on a number of factors. The morphology of the tissues, the histology, and immunologic findings are all used in diagnosis of the form of the condition. However, as suggested previously, there is some confusion in the distinction of the different forms of contact dermatitis. Using histology on its own is insufficient, as these findings have been acknowledged not to distinguish, and even positive patch testing does not rule out the existence of an irritant form of dermatitis as well as an immunological one. It is important to remember, therefore, that the distinction between the types of contact dermatitis is often blurred, with, for example, certain immunological mechanisms also being involved in a case of irritant contact dermatitis.

See also

  • Urushiol-induced contact dermatitis
    Urushiol-induced contact dermatitis
    Urushiol-induced contact dermatitis is the medical name given to allergic rashes produced by the oil urushiol, which is contained in various plants, including the plants of the genus Toxicodendron , other plants in the family Anacardiaceae Urushiol-induced contact dermatitis (also called...

  • Eczema
    Eczema
    Eczema is a form of dermatitis, or inflammation of the epidermis . In England, an estimated 5.7 million or about one in every nine people have been diagnosed with the disease by a clinician at some point in their lives.The term eczema is broadly applied to a range of persistent skin conditions...

  • List of cutaneous conditions

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