Allergic contact dermatitis Flashcards
allergy
exaggerated rxn of immune system following contact w/ foreign substance
allergen
substance that causes or elicits allergic rxn
eczema
red, itchy, weepy patches of skin
allergic contact dermatitis risks
anyone; atopy (predisposition for allergies)
allergic contact dermatitis happens how?
1) sensitiization or induction (first contact); 2) elicitation (develop rash after re-exposure)
How does sensitization to an allergy occur?
contact or open skin allows the loss of barrier fxn leading to first contact of allergy
Step 2 of allergic contact dermatitis occurs how?
2nd contact w/ allergen leads to memory T cells leading to elicitation of the rash
What are the Sx of acute allergic contact dermatitis?
itchy, red, crusting, blisters
What are the Sx of chronic allergic contact dermatitis?
itch (+/-); less red; hyperpigmentation; thickened skin; few blisters
Where does allergic contact dermatitis typically affect?
at site of contact to allergen
Describe the allergic contact dermatitis as a type IV HSR
Sx 24-48hrs later with faster rxns with more exposure leading to rash of 7-14 days with no hives or wheezing
What are distinguishable characteristics of rash from poison ivy?
linear pattern with Sx of mild itch to severe itch with blisters
T/F poison ivy can be spread in blister fluid
false
How can a person get poison ivy without direct contact?
urushiol is present in vines leading to spread by contact or in burning it in the air
What are some common allergic contact dermatitis allergens?
CHEMICALS => nickel; fragrances; preservatives; rubber products; topical antibiotics; plants
When should you be careful for nickel allergies?
piercing associated with jewelry, metal objects, clothing; medical devices
Other than nickel in outside objects, where else is it something to be wary of?
dietary nickel
What are the recommendations for nickel allergies?
avoid exposure to nickel compounds; low nickel diet
T/F Allergies to fragrances is 2nd most common allergy
true => many different components cause (natural and synthetic)
Where can fragrances be found?
most personal care products (even those that say unscented)
Where do fragrance allergies typically present?
face, neck, skin around eyes
How is testing for fragrance allergy done?
testing through “mixes” that contain many compounds
What is widely used in cosmetic, pharmaceuticals, and industrial application to prevent bacterial and fungal overgrowth?
preservatives (formaldehyde, parabens)
Where are reactions to preservative allergies typically found?
site of contact or relatively diffuse with testing needed to detect/confirm allergy
What are the types of rxns associated with rubber?
1) immediate type rxns to latex proteins (hives, itching, wheezing, anaphylaxis);
2) delayed type rxns to chem additives in rubber products (eczematous rxns)
A physician notices an immediate rxn when he got ready to do his procedure. What type of rxn does he probably have? How does it cause it?
latex allergy leading to immediate type HSR that can be found in latex glove powder
What can lead to bleached rubber syndrome?
use of chlorine bleach makes carbamates in elastic more allergenic
Topical antibiotics may lead to allergic rxns. What increases the likelihood of this happening?
topical antibiotics on open skin (dermatitis) may increase chance of developing allergy;
2 drugs cross reacting;
Rxns confused for infection
What is the gold standard for allergic contact dermatitis?
patch testing due to dermatologists being able to predict relevant allergens only 50% of time
What does prick testing test for?
immediate type hypersensitivity rxns (detects allergies in foods, trees, grasses, molds, pets)
What does patch testing test for?
delayed type HSR from chemicals, metals, preservatives, fragrances
How do you treat allergic contact dermatitis?
symptomatic relief with cool compresses, oatmeal bathes, calamine lotion; topical corticosteroids
What should you avoid in Tx of allergic contact dermatitis?
caladryl or product with topical benadryl which is potent sensitizer
What is an effective means to avoid delayed typic HSR for allergic contact dermatitis?
avoid the causative agent but NO ALLERGY SHOTS
