Every year, when spring rolls around, millions of Americans start sneezing and coughing. The culprit is allergies. An allergy is simply a negative reaction to a substance that enters the body that is not toxic in itself, yet for some reason causes a bad reaction in the body. Just about anything can be an allergen: dust mites, pollen, cats, dogs, wasps or bees, milk, eggs, peanuts, and even fruits are the most common.
A normal immune system is the body's defense against invading bacteria and viruses. It senses potential invaders and attacks them by producing antibodies. But sometimes a person's immune system mistakes a common allergen as harmful. So it produces antibodies to attack them, and this triggers other cells to release chemicals called histamines, causing allergic symptoms.
The most common symptoms of an allergic reaction include sneezing, swelling, itchy eyes, sinus pain, a runny nose, rashes or hives, coughing, and in vomiting. In extreme cases, an allergen can cause difficulty in breathing. This is called an anaphylactic reaction, and a severe attack can be fatal if not treated quickly. More than 29,000 people in the U.S. end up in the emergency room every year because of anaphylactic shock.
If you have a bad reaction to any food or additive that involves the immune system, you have a food allergy. But the majority of toxic reactions to food are due to food sensitivities, which do not involve the immune system. A food may just contain a molecule that your body has trouble digesting.