What Causes Allergic Contact Dermatitis? What are the Treatment Methods?

In this publication, What is Contact Dermatitis, What Causes Contact Dermatitis, What are the Treatment Methods for Contact Dermatitis? You can find a
What Causes Allergic Contact Dermatitis? What are the Treatment Methods?


What Causes Allergic Contact Dermatitis? What are the Treatment Methods?

In this publication, What is Contact Dermatitis, What Causes Contact Dermatitis, What are the Treatment Methods for Contact Dermatitis? You can find answers to questions such as:

Contact dermatitis is skin inflammation caused by direct contact with a particular substance. The rash, which may be itchy, is limited to a limited area of skin and usually has well-defined borders.

Contact dermatitis is caused by an irritant or allergic reaction. A rash develops, which may be itchy and/or painful.

Diagnosis is based on the appearance of the rash and what substances the person has been exposed to. Individuals should avoid or protect themselves from substances that cause dermatitis. Treatment includes removing the dermatitis-causing agent, measures to relieve itching, applying corticosteroids to the skin, and sometimes bandages.

Substances can cause skin inflammation through two different mechanisms:

  • Irritation (irritant contact dermatitis)
  • Allergic reaction (allergic contact dermatitis)

 Irritant Contact Dermatitis

This type of dermatitis, which is the cause of most cases of contact dermatitis, occurs when a toxic or chemical substance comes into contact with the skin and directly damages the skin. In the case of irritant contact dermatitis, the pain may be worse than the itching. Irritants include but are not limited to:

  • Acids
  • Lyes (like a drain cleaner)
  • Solvents (like acetone in nail polish remover)
  • Aggressive soaps and detergents
  • Plants (e.g. pepper plants)
  • Body fluids (eg urine and saliva)

Some of these substances are extremely irritating and cause skin changes within minutes, while others are less irritating or require prolonged contact to be effective. Even mild soaps and detergents can irritate some people's skin after frequent or prolonged exposure. People differ significantly in how sensitive their skin is to irritants. Factors that influence whether irritant contact dermatitis develops include the person's age (too young or too old) and environment (low humidity or high temperature).

Materials in contact with the workplace can also cause dermatitis (occupational dermatitis). It can occur immediately after exposure or only after prolonged and repeated contact.

Sometimes irritant contact dermatitis develops only when someone touches or swallows certain substances and then exposes the skin to sunlight (phototoxic contact dermatitis - see chemical photosensitivity). Regardless of whether the substance is touched, inhaled, or swallowed, the rash only develops on skin exposed to sunlight. Such items include:

  • Some antibiotics when taken by mouth
  • Certain blood pressure lowering agents (antihypertensives) or diuretics when taken by mouth
  • Some perfumes
  • Nonsteroidal anti-inflammatory drugs (NSAIDs) when taken by mouth
  • Coal tar
  • Some plants
What Causes Allergic Contact Dermatitis? What are the Treatment Methods?

Allergic Contact Dermatitis

In this type of dermatitis, the immune system reacts to the contact of a substance with the skin. When the skin first comes into contact with a substance, it becomes sensitive to that substance. Sometimes a person is already sensitized by a single contact, in other cases multiple contacts are required. Once sensitized, subsequent exposure to the substance will cause itching and dermatitis within 4 to 24 hours, although some people may not develop allergic symptoms for three to four days.

Thousands of substances can cause allergic contact dermatitis. Most commonly, substances are found in:

  • Metals (eg nickel)
  • Protectors
  • Plants (e.g. poison ivy)
  • Rubber (including latex)
  • Fragrances
  • Nickel sulfate is the most common contact allergen in most populations. It is a common component of jewellery. You can handle a particular substance for years without any problems and then suddenly and unexpectedly have an allergic reaction to it. Even ointments, creams and lotions used to treat dermatitis can trigger such a reaction.

Sometimes allergic contact dermatitis develops only when someone touches or swallows certain substances and then exposes the skin to sunlight (phototoxic contact dermatitis—see Chemical photosensitivity). With photoallergic dermatitis, the reaction can spread to areas of the skin that are not exposed to the sun. Typical causes include fragrances (such as musk and sandalwood), antiseptics, nonsteroidal anti-inflammatory drugs (NSAIDs), and sunscreens.

Contact Dermatitis Symptoms

Whatever the cause or type, contact dermatitis causes itching and redness.

Irritant contact dermatitis is more painful than itching. Symptoms usually subside after a day or two with no further contact with the irritant.

Allergic contact dermatitis usually causes more itching than pain. It may take one or more days for symptoms to appear and increase in intensity for two to three days after exposure.

In both cases, the rash ranges from mild, temporary redness to severe swelling and large blisters. It develops only where the skin comes into contact with the allergenic substance. The rash first appears on sensitive areas of the skin, such as between the fingers, and later on thicker areas of the skin or those with less intense contact with the allergen. Small blisters may accompany the rash on the hands and feet.

Often the rash pattern in allergic contact dermatitis suggests exposure to a particular substance. For example, poison ivy causes streak-like lines on the skin. Contact dermatitis cannot spread to other parts of the body or to other people who have not come into contact with the substance in question.

What Causes Allergic Contact Dermatitis? What Are The Treatment Methods?


Diagnosing Contact Dermatitis

The patient's medical history and assessment by the physician

Sometimes a patch test

Identifying the cause of contact dermatitis is not always easy. A person's occupation, hobbies, household chores, travel, clothing, use of topical (applied to the skin) medications, cosmetics, and activities of other household members should be considered. Most people are unaware of the large number of substances that come into contact with their skin. Often, the origin and shape of the original rash provide an important clue, especially if the rash first appeared under a particular piece of clothing or jewelry or only on areas of skin that were exposed to sunlight. However, many substances touched by the hand are unconsciously transferred to the face,

If contact dermatitis is suspected and elimination cannot determine the cause, a patch test may be done to identify the substance (allergen) causing the allergic reaction. For this test, small patches containing common contact allergens are placed on the skin of the upper back for 48 hours to see if the underlying rash develops. They are removed after 48 hours and the doctor evaluates the underlying skin. The skin is examined again after a day or two.

Prognosis in Contact Dermatitis

Allergic contact dermatitis can take several weeks to resolve after exposure to an allergen. Irritant contact dermatitis usually goes away more quickly. When a person reacts to a substance, it often triggers a lifelong reaction.

People with photoallergic contact dermatitis can have reactions (called persistent photoreactions) after years of exposure to sunlight, but this is rare.

Prevention of Contact Dermatitis

Contact dermatitis can be prevented by avoiding contact with substances that cause dermatitis. If contact does occur, the item should be washed immediately with soap and water. If there is a risk of frequent exposure, gloves and protective clothing can help. People with phototoxic or photoallergic contact dermatitis should avoid sun exposure.

Barrier creams are also available that can prevent certain substances from coming into contact with the skin, such as poison ivy and epoxy resins. Desensitization using injections or tablets containing the causative agent is not effective in preventing contact dermatitis.

Contact Dermatitis Treatment

  • Avoid contact with the substance causing the problem
  • Measures to relieve itching
  • Corticosteroids and antihistamines

Contact dermatitis treatment will fail as long as contact with the offending substance continues. The redness usually subsides over time after the allergy-causing substance is removed. Blisters and blisters may continue to weep and crust for a while, but they dry up soon. The flaking, itching, and thickening of the skin can last for days or weeks.

Itching and blisters can be relieved with various drugs applied to the skin or taken orally. Additionally, gauze or a thin cloth dipped in cold water or acetic clay (Burow solution) can be applied to small inflamed areas of the skin for an hour several times a day. Wet bandages that dry afterward can soothe oozing blisters, keep the skin dry, and aid healing.

Those affected are usually treated with a corticosteroid. Over-the-counter hydrocortisone can help. If not, a stronger corticosteroid cream may be prescribed. If the rash is particularly severe, an oral corticosteroid may also be taken. Antihistamines hydroxyzine and diphenhydramine relieve itching. They are taken orally.

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