The first step in allergy control is pinpointing the substances that trigger your allergic response. Sometimes it's obvious: you pet a cat, rub your eyes, and bingo — your eyes are itchy and watery. Or you eat lobster tails at a buffet and soon your throat is itching and swollen. But the cause of an allergic reaction is not always apparent. It may be that several different substances affect you or that different substances are at work at different times of the year (see Table 1). People are generally allergic to only a small handful of substances. Still, despite your deductive powers, the causes of your allergies can remain elusive, and your doctor may recommend that you see an allergist (see "Seeing a specialist," below).
There are a number of bona fide approaches to diagnosing allergies, including several types of skin tests, blood tests, elimination or avoidance diets, and challenge testing (see Table 2). Each has advantages and disadvantages depending on the nature of the allergy and its severity. There are also a number of unreliable tests, and others that should be avoided altogether (see "Complementary and alternative diagnostics").
Seeing a specialist
Your primary care doctor may want help in treating your allergies. He or she may refer you to an ear, nose, and throat specialist for management of rhinitis and sinusitis, to a pulmonologist for management of asthma, or to a dermatologist if you have hives or dermatitis. An allergist is also trained to see people with these complaints and, in addition, has the tools and training to identify the offending allergens. Since allergies involve the immune system, of necessity the allergist will be expert in the workings of the immune system. Working with an allergist-immunologist helps patients control their disease, which, in turn, minimizes harmful effects.
To become board certified to practice as an allergy specialist, a doctor must first complete residency training in either internal medicine or pediatrics and then spend two to three years studying allergies and the immune system in depth. Most allergists focus on diagnosing and treating allergies in adults and children. Some have a particular interest and expertise in treating other immunological diseases.
Tell it like it is
The first and most important step in any diagnosis is compiling an accurate account of your allergy attacks. Doctors call this account your history. Allergy testing is effective only when you and your allergist have some idea of what you are testing for. A detailed description of your symptoms and the situations that trigger them is invaluable in whittling down the possibilities. Be prepared to describe not just your current situation and what you assume are the likely allergens, but also what happened in your childhood and whether family members have allergies. It's a good idea to jot down your allergy history before your appointment with your allergist, lest you inadvertently leave out something that may be important.
When you visit your allergist, be prepared to answer the following questions:
Do your allergies occur at a particular time of the year?
How early in the year do your symptoms start?
When do they finish?
Are they provoked by molds, dust, or animals? Be as specific as possible. For example, are they provoked by compost or a moldy bathroom or basement?
Are they provoked by certain foods?
Do other environmental stimuli, such as perfumes or cold air, trigger your symptoms?
Your doctor will need details of your home and work environment and a list of all the medications you are taking, including prescription, over-the-counter, and alternative medications and supplements. And you will need to provide the details of your other medical conditions, as these may influence the severity and treatment of your allergies and vice versa. The value of a detailed history cannot be overemphasized. If you shortchange this initial step, you're less likely to come up with what triggers your allergic reactions. It's also important to correlate the triggers you identify with those identified by testing.