An allergy causes your body to react to a substance that is harmless to other people. This can occur from material in the air like pollen or pet dander, foods like peanuts and chemicals such as those in medications.
Allergies can also occur from things that come in direct contact with our skin such as the metal nickel or latex.
Allergy-producing substances are called allergens. Allergens can stimulate allergy antibodies called immunoglobulin E (IgE), which are proteins produced that fight against the allergen.
IgE binds to mast cells (immune response cells) and causes them to release histamine along with other chemicals. This reaction sets off an entire allergic cascade many of us are familiar with.
Your eyes become itchy, your nose starts to run, and you sneeze. Your breathing may become tight and hopefully does not progress to a serious reaction called anaphylaxis, which can be life-threatening.
Allergies can be difficult to diagnosis. A thorough history and physical exam is performed in addition to skin and blood tests to rule out any other potential causes of symptoms being attributed to allergies.
The basic premise behind skin or blood testing is that suspected allergens can be tested for by using controlled standard methods that provide objective proof that your body reacts to that substance.
There are three basic types of skin tests: skin prick, skin injection and patch testing.
- Skin prick tests, also called scratch tests, can check for an immediate reaction to up to 40 different substances, said the Mayo Clinic.
This test is commonly done to test allergies to inhaled substances such as pollen and dust mites, but also can be done to check for food allergies.
A nurse prepares the skin area with alcohol and marks what is to be tested in each spot of skin. She puts a small amount of allergen in each area and uses a lancet to scratch the skin to expose your body directly to the potentially allergic substance.
If you have a reaction, it will usually appear within 15 minutes as a wheal (raised, red, itchy bump) that may look like a mosquito bite.