Allergens are things that can trigger allergy symptoms in susceptible people.
They include everything from well-known allergens, such as ragweed, peanuts, and pet dander, to things that you likely wouldn't think of, such as viruses, antibiotics and even paraphenylenediamine -- an ingredient in temporary henna tattoos.
The other surprising thing about allergens is that they can trigger a wide range of allergy symptoms, such as:
- itchy red skin rash - from nickel, known as contact dermatitis
- runny nose and itchy eyes - from ragweed, known as allergic rhinitis
- itchy red rash that comes and goes - from peanuts, known as hives
Contact Allergy
Unlike allergic rhinitis (hay fever) or hives, in which you usually have to inhale or ingest the allergen, with a contact allergy, you simply have to get the allergen on your skin to get a reaction.
Also called allergic contact dermatitis, common triggers of contact allergy include:
- nickel
- rhus dermatitis or poison ivy
- fragrances in cosmetics
- latex
- ingredients in topical medications, such as neomycin and bacitracin (antibiotics), PABA (sunscreens), and lidocaine (topical anti-itch creams)
- chemicals, including some used to tan leather, as a component in rubber, or as an ingredient in shoe glues
- botanical extracts
- para-phenylenediamine, a chemical found in hair dye and which is often added to temporary henna tattoos to make them darker and last longer
Although poison ivy often gets the most attention when it comes to contact allergies, a nickel allergy is actually more common. In fact, nickel was named the "2008 Allergen of the Year" by the The American Contact Dermatitis Society.
Like other contact allergies, a child with a nickel allergy will often develop a red, itchy rash on his skin where he had contact with nickel, such as is found in jewelry, zippers, snaps on clothing, belt buckles, eye glass frames, etc.
Although contact allergies can often be treated with topical steroid creams, it's usually best to try and avoid contact with whatever your child is allergic to. A dermatologist can do patch testing to help you figure out exactly what your child is allergic to if you aren't sure.
Allergic Rhinitis
Allergic rhinitis is the most classic type of allergy that people are familiar with. After exposure to allergens, such as ragweed, dust mites, or pet dander, etc., children can develop symptoms of allergic rhinitis, such as:
- runny nose with clear discharge
- stuffy nose (congestion)
- sneezing
- itchy nose
- red eyes, with tearing and itching
As with contact allergies, there are many different allergens for allergic rhinitis. The most common are:
- Indoor Allergens - dust mites, indoor molds, pet dander, and cockroaches, which typically cause year-round or perennial allergy symptoms
- Seasonal Allergens - mold and pollens from trees, grasses, and weeds, which are more likely to just cause allergy symptoms during the season that they are around, like when ragweed in the fall
Although simply trying to avoid common allergens or the specific things that you think are triggering your child's allergies are sometimes helpful, allergy testing is another option, especially if your child has hard-to-control allergies.
Hives
Although there are common allergens, such as peanut butter and eggs, that you should think about when your child has hives, it is important to keep in mind that almost anything can trigger hives, including:
- foods, especially peanuts, eggs, tree nuts, milk, shellfish, wheat and soy
- medications, especially antibiotics like penicillin and sulfa drugs
- additives in foods or medications, such as the food dye tartrazine (Yellow No. 5) and sulfites
- infections, especially viral infections
- insect bites and stings
- latex
- exercise
- stress
- exposure to heat, cold, or water, no matter what the temperature is
- dermographism, a physical urticaria, in which hives are triggered by stroking the skin, such as by scratching
Sources:
Habif: Clinical Dermatology, 4th ed.
Behrman: Nelson Textbook of Pediatrics, 17th ed.
