Identifying the allergens responsible for your allergy symptoms is key to preventing and controlling your allergies. This can require detective work on your part. You should begin your research by watching for a pattern in your symptoms.
Start by asking yourself these questions:
- What are your symptoms? If your symptoms involve dripping and itching from your eyes or nose, sneezing, or wheezing (asthma), then your allergy triggers are probably airborne proteins such as pollens, animal dander, molds, or allergens that come from cockroaches or dust mites. Skin rashes can come from direct skin contact, from swallowed foods or medicines, or from insect stings. Anaphylaxis is usually caused by swallowed foods or medicines, or by insect venom. Rarely, it results from a significant contact exposure, as in the case of latex allergy.
- What were you doing when symptoms began? Airborne allergy symptoms usually begin within minutes after exposure to an allergen, so if you were petting an animal, vacuuming the house, mowing the lawn or raking leaves, you have some important clues. Rashes can appear two to four days after exposure to an allergen such as a cosmetic ingredient, a food, or poison ivy.
- Are your symptoms present year-round or only during certain seasons? Tree and grass pollens are abundant in the spring, but ragweed pollen is produced in the fall. Animal dander, cockroaches, and dust mites can be present year-round, but these allergens may accumulate more in months when a home is more carefully sealed to keep out cold winter weather. Mold builds during the winter when the home is less well ventilated, too.
- If you have nasal symptoms or asthma, are your symptoms at their worst in the mornings? A full night of close-up exposure to dust-mite deposits may be the cause. You should launder your sheets and bed coverings in hot water every week and consider allergy-control mattress and pillow covers.
- Are your symptoms more noticeable at home or work? This may not give you very specific information about your allergies, but it can direct you to compare the ventilation of the two buildings that you frequent most often, and to consider indoor allergens.
When the answers to these questions don't produce any obvious pattern at first glance, keeping a diary might help. This can be especially valuable in the case of food allergy, since symptoms frequently come after a delay of more than a day. You may find that your potential allergen follows an irregular pattern of exposure. Perhaps you have symptoms on days when you meet with a certain person. The allergen that is causing you to react may be animal dander on that person's clothes. Applying cologne or perfume with certain additives can result in allergic contact dermatitis or hives.
For people with recurrent hives, be aware that hives don’t always have an allergy source. A persisting fungal or viral infection (such as hepatitis), sun exposure, hot showers or sweaty workouts also can cause recurrent hives.