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Facts & Symptoms

Allergies are one of the most common chronic diseases, which lasts a long time or occurs often. Each year more than 50 million Americans suffer from allergic diseases. They affect as many as 30 percent of adults and 40 percent of children.[1] Allergic disease, including asthma, is the fifth leading chronic disease in the U.S. in people of all ages. It is the third most common chronic disease in children under 18 years old.[1]

Respiratory Allergies

  • Itchy eyes, mouth, and throat
  • Sneezing, wheezing, nasal congestion, and coughing
  • Loss of smell or taste
  • Dark circles under the eyes caused by increased blood flow near the sinuses (allergic shines)

Food Allergies

  • Stomachache, frequent indigestion, and heartbum
  • Stiffness, pain, and swelling of joints may indicate food or drug allergies
  • Fatigue or feeling run-down, difficulty concentration, emotional upset or irritability, or difficulty sleeping may be associated with food allergies or seasonal allergies, such as hay fever
Comon Causes

Allergy is caused by an oversensitive immune system, which leads to a misdirected immune response. The immune system normally protects the body against harmful substances, such as bacteria and viruses. In contrast, an allergic reaction is when the immune system reacts to substances (allergens) that are generally harmless and in most people do not cause an immune response.

In a person with allergies, the first exposure to the allergen triggers the immune system to recognize the substance. Any exposure after that will usually result in symptoms.

When an allergen enters the body of a person with a sensitized immune system, histamine and other chemicals are released by certain cells. This causes itching, swelling, mucus production, muscle spasms, hives, rashes, and other symptoms.

Symptoms vary in severity from person to person. Most people have symptoms that cause discomfort without being life-threatening. A few people have life-threatening reactions (called anaphylaxis).

The part of the body contacted by the allergen will, in part, affect the symptoms. For example, allergens that are inhaled often cause nasal congestion, itchy nose and throat, mucus production, cough, or wheezing. A food allergen can cause nausea, vomiting, abdominal pain, cramping, diarrhea, or a severe, life-threatening reaction. Allergies to plants often cause skin rash. Drug allergies usually involve the whole body.

Some disorders may be associated with allergies. These include eczema and asthma, among others.

Common allergens include those that contact the skin, breathing passages, or the surface of the eye (such as pollen; see also allergy to mold, dander, dust). Food allergies and drug allergies are common. Allergic reactions can be caused by insect bites, jewelry, cosmetics, and almost any substance that contacts the body.

Some people have allergic-type reactions to hot or cold temperatures, sunlight, or other physical stimuli. In some persons, friction (rubbing or vigorously stroking the skin) will cause symptoms.


The best way to prevent an allergy is to recognize that you have one. Often people confuse an allergy with a cold or flu. Remember colds are short-lived and passed from person to person, whereas allergies are immune system reactions to normally harmless substances. Allergies are best prevented by avoiding exposure to allergens in the first place.

Respiratory Allergies

  • Install a high efficiency air cleaner to help remove pollen and mold spores, and use air conditioner in your home and car during warm seasons to keep pollen out
  • Regularly clean damp areas with bleach to kill moles
  • Isolate your pets and keep them outside as much as possible. Regular baths for your pet will help reduce dander

Food Allergies

  • Avoid foods that are highly allergenic, such as dairy products, wheat, corn, soybean, and citrus fruits. Try tofu-based foods
  • Always check food labels for additives that are known allergens, such as yellow food dye no. 5 and gum Arabic
  • If you experience symptoms, avoid any further contact with that food item, rinse your mouth and see a doctor