poison ivy rash - contact dermatitis

POISON IVY RASHALLERGIC

CONTACT DERMATITIS

Poison Ivy Rash

Poison ivy, poison oak, and poison sumac are plants that can cause a skin rash called allergic contact dermatitis  when they touch your skin. 

The rash is caused by contact with an oil (urushiol) found in these plants.

Contact Dermatitis

Contact dermatitis is a localized rash or irritation of the skin caused by contact with a foreign substance.

Types of Contact Dermatitis

There are three types of contact dermatitis: 

irritant contact dermatitis allergic contact dermatitis photo contact dermatitis. 

Irritant Contact Dermatitis

−caused by chemical and physical irritant that damages skin's outer protective layer

−Common chemical irritants:• solvents

(alcohol, xylene, turpentine, esters, acetone,ketones)• latex• Kerosene

• ethylene oxide• surfactants in topical medications

and cosmetics (sodium lauryl sulfate)• alkalis (drain cleaners, strong soap)

- Physical irritant contact dermatitis is commonly caused by low humidity from air conditioning.

Allergic Contact Dermatitis

−occurs when a substance to which you're sensitive (allergen) triggers an immune reaction in your skin.

−Common causes of allergic contact dermatitis are plants of the Toxicodendron genus:

- poison ivy- poison oak- poison sumac 

Photo Contact Dermatitis− is the eczematous condition which is

triggered by an interaction between an otherwise unharmful or less harmful substance on the skin and ultraviolet light.

−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.

Signs & Symptoms

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 (the layer beneath the epidermis).

Contact dermatitis results in large, burning, and itchy rashes

Takes several days to weeks to heal

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.

• Red rash. 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, wheals (welts), and urticaria (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.

Medical TreatmentMedical treatment usually consists of lotions,

creams, or oral medications. Corticosteroids

- may be prescribed to combat inflammation in a localized area.- in a cream or ointment form.- 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. Oral antihistamines such

as diphenhydramine (Benadryl, Ben-Allergin) can also relieve itching.

Prescription antihistamines may be given if non-prescription strengths are inadequate.

Self-care at homeImmediately 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 irritants.

If blistering develops, cold moist compresses applied for 30 minutes 3 times a day can offer relief.

Avoid scratching, as this can cause secondary infections.

Calamine lotion and cool colloidal oatmeal baths may relieve itching.

For mild cases that cover a relatively small area, hydrocortisone cream in nonprescription strength may be sufficient.

A barrier cream such as those containing zinc oxide (e.g. Desitin, etc.) may help to protect the skin and retain moisture.

Prevention

Allergy testing- patch tests done to identify the responsible agent and avoid it. The patient must know where the irritant or allergen is found to be able to avoid it.

protective clothing, gloves or barrier cream should be used depending on the working environment.