Allergic skin conditions are fairly common, but it can be difficult in many cases to find a cause.
Skin reactions can be caused by a number of different factors such as immune disorders, medications, infections, and allergens. If an allergen is the cause, then it is labeled an allergic skin condition.
Eczema or Atopic Dermatitis
Eczema is a very common allergic skin disorder often seen in children, and adults as well.
A defect in the skin barrier causes skin to dry out and become irritated and inflamed. This causes patches of sand-paper like skin in flexural areas of the arms and legs, trunk, and even the neck and face. Chronically affected areas can become leathery in appearance. It is often said that eczema is an itch that rashes rather than a rash that itches. The itch in eczema is not caused by histamine, and this means that antihistamines often will not completely control this symptom. Young children with eczema have a 35-40% chance of having some food allergy.
Food allergy to eggs is the most common food allergy seen with eczema patients. Food sensitivities can make eczema symptoms worse. Patients with eczema have increased risk for asthma and allergic rhinitis as well.
If during a skin reaction histamine is released, then small blood vessels will leak. This leads to swelling and inflammation of the skin. This is what is often referred to as hives. If the reaction occurs in the deeper layers of the skin, it is known as angioedema.
There are 2 types of urticaria. Acute urticaria can be caused by a number of various triggers including viral or bacterial infections, medications, foods, insect bites, heat or exercise.
These episodes are usually short-lived, and usually respond to standard treatment with antihistamines. Chronic urticaria is defined by having consistent symptoms for 6 weeks or longer, and can last for months or years. Evaluation and treatment of chronic hives can be considerably more difficult. In most cases, there is no obvious cause for chronic urticaria.
Treatment centers around antihistamines and in recent years the use of omalizumab or xolair.
Xolair is an antibody that targets the allergic antibody(IgE), and renders it essentially inactive for a period of time. It has shown to be very effective in treating chronic idiopathic urticaria.
Angioedema is often seen in conjunction with hives, and is caused by swelling in deeper skin layers. This swelling most often occurs in soft tissues like face, hands, feet, and genitals. Treatment is often very similar to treatment used for urticaria except in rare cases.
Allergic Contact Dermatitis
Allergic contact dermatitis is an allergic skin condition which is caused by an allergen that comes in contact directly with the skin. Reactions are usually delayed and cause red, inflamed skin which can have some blisters or patches of bumpy, itchy skin.
Common causes include the Rhus plants including poison ivy, sumac and oak.
Metals like nickel are also a common cause of this allergic skin condition.
Treatment centers on the use of topical and/or oral steroids and antihistamines. If symptoms become chronic, further evaluation with patch testing might be helpful to identify allergic contactants. The only prevention is avoidance of known skin allergens.