Allergy and the skin Flashcards
What is hypersensitivity?
Immune response that causes collateral damage to self
What is type I hypersensitivity?
IgE mediated hypersensitivity that has an immediate reaction to allergen (from minutes - 2 hours)
What is type IV hypersensitivity?
T-cell mediated hypersensitivity that has delayed reaction to allergen (typically 12-24 post exposure)
Name some common allergens in type I hypersensitivity?
Food - nuts, seafood
Inhalation - pollen, dust mites
Skin contact - latex, animal dander
Injection - bee stings, medications
What are the common clinical presentations of allergy?
Urticaria
Angioedema
Nausea / vomiting / diarrhoea
Colicky abdominal pain
Wheezing
Sneezing / nasal itching
Anaphylaxis
What are the investigations of choice for allergy?
History - most important
Specific serum IgE
Skin prick test
Challenge test
What is the 3 step treatment for severe allergy?
- Give antihistamines (chlorphenamine)
- Give corticosteroids (prednisolone)
- Give IM adrenaline
What are the two types of food allergy?
IgE mediated
Non-IgE mediated
Give examples of non-IgE allergic reactions?
Coeliac disease
Morphine / aspirin reactions
Lactose intolerance
Name some common allergens in type IV hypersensitivity?
Skin contact - preservatives, rubber accelerators
Airborne - fragrances, plants
Injection - tattoo
How are type IV hypersensitivity reactions tested for?
Patch testing
What is irritant contact dermatitis?
A non-immunological process in which contact with agents can abrade and irritate skin
Give some common agents which cause irritant contact dermatitis?
Detergents
Cleaning products
Solvents
What is atopic eczema?
Dry skin on flexural surfaces which is often associated with asthma & hayfever
How is skin allergy managed?
Avoidance of allergen / irritant
Emollients
Topical steroids
Immunosuppressants
