Some people sneeze when confronted with ragweed pollen or dander from cats. And some people break out in a rash, known as allergic contact dermatitis, when their skin comes in direct contact with substances that are normally harmless to most people, such as certain ingredients in costume jewelry or makeup.
In allergic contact dermatitis, the body's immune system reacts to direct contact with an allergen (a substance the body incorrectly identifies as harmful) by producing an itchy rash on the skin where that contact occurred. So, for example, a person with an allergy to the nickel in a bracelet will develop a bracelet-shaped rash on the skin where that piece of jewelry was worn.
The most common allergen in allergic contact dermatitis is poison ivy, which can cause reactions in at least half of the people exposed to it. The next most common contact allergen is nickel, a metal commonly used in costume jewelry. Up to 10 percent of the population may suffer an allergic reaction to this metal.
Other possible causes of allergic contact dermatitis include:
Neomycin or benzocaine in topical anesthetics
Leather
Formaldehyde, which is used in shampoo, detergent, nail hardeners, waterless hand cleaners, and mouthwashes
Cinnamon flavoring in toothpaste and candies
PABA, the active ingredient in some sunscreens
Chemicals found in hair dyes
Preservatives in cosmetics
Identifying a rash as allergic contact dermatitis is not always easy, however. An airborne allergen, like ragweed or animal dander, usually elicits sneezing or a runny nose within 15 minutes of exposure. But it may take up to 72 hours after contact with the sensitizing substance before a reaction shows up on your skin. That can make identifying the culprit and choosing a home remedy pretty tough.
Complicating the diagnosis further is the fact that you have to become sensitized to a substance before it can cause a rash. That means you have to come in contact with it at least once before the next contact will provoke an allergic response. And indeed, sometimes it requires repeated contacts with a substance before the body becomes sensitized to it. So, for example, you may wear that nickel-containing bracelet once or even dozens of times without any problems, but then one day, out of the blue, it causes an allergic rash.
Isolating the cause of a rash and selecting a home remedy can be challenging, since it may be triggered by tiny amounts of the offending chemicals. What's more, it may take only a tiny amount of the offending substance to cause an allergic rash, and thanks to our concerns with hygiene and appearance, we expose ourselves to a variety of potentially offending substances every day. For instance, the average woman uses more than a dozen different products on her scalp and head each morning.
How can you handle allergic contact dermatitis?
Ferret out the cause. If the rash won't go away or keeps reappearing in the same place, you're going to have to play detective to find out what's causing it. Otherwise, you're stuck with treating only the symptoms. It may help to make a list of everything that came into contact with the affected area of skin within the last three days, including hygiene products, cosmetics, perfumes, jewelry, and even clothing (the clothing itself may not be to blame, but a detergent, fabric softener, or dry-cleaning agent used in cleaning the clothes may). If you're having trouble pinning down the cause, a dermatologist (skin doctor) or allergist (doctor specializing in allergies) can help. Either can do a test using common allergens (called a patch test) and ask you the right questions to zero in on the culprit.
Stay away. Once you've determined the cause, avoid the offender as much as possible. Your rash will continue as long as your skin continues to contact the allergen, and it will return if you again expose yourself to the offending substance.
Don't sweat it. If you are sensitive to nickel, wearing nickel-containing jewelry in a hot, humid environment may worsen the allergy, as perspiration leaches out some of the nickel. So before you start a workout or go out into the heat, take off any nickel-containing jewelry.
Use caution with ear-piercing. If you decide to get your ears pierced but you have an allergy to nickel, make sure those first earring studs have stainless steel posts. Also make sure the needle is stainless steel. Otherwise, the studs or needle may contain nickel, and you'll be risking an itchy, inflamed rash on those recently pierced earlobes.
Coat nickel jewelry. Paint the surfaces that come in contact with your skin with clear nail polish.
Choose only the best. Even 14 karat gold jewelry has some nickel in it, so if your skin reacts strongly to nickel, you may need to restrict your gold purchases to 24 karat (which is pure gold). Other safe options include platinum and stainless steel.
Become a label reader. If your skin breaks out in a rash when it meets PABA or another chemical common in consumer products, do your skin a favor by reading ingredients lists carefully and choosing only those without the offender. Some products are even conveniently labeled as "free" of certain substances known to cause allergic reactions (you will likely find sunscreens, for example, advertised and labeled as "PABA-free").
Don't depend on the "hypoallergenic" label. It's an ambiguous term with no legal meaning. The Food and Drug Administration has not established a standard to define "hypoallergenic." If you can't tell whether a product contains a substance you're allergic to, try querying the manufacturer or performing your own patch test by applying a little of the product on the skin of your inner forearm and waiting three or four days to see if a rash develops.
Protect your skin. Guard against exposure to poisonous plants by wearing long pants and long-sleeved shirts when you're in areas where these plants are likely to be.
