Test Your Knowledge

There are significant differences in the causes of allergies and infectious conditions, such as the common cold. However, both begin with a similar immune system reaction. The immune system produces antibodies to neutralize, metabolize or eliminate a substance the body identifies as foreign.

In the case of a cold, infection or flu, the foreign bodies are harmful bacteria, fungi, viruses or parasites. The immune system’s response to these invaders helps the body to lessen or prevent damage from these harmful substances. For instance, during a cold, nasal discharge can last up to two weeks. Drainage of this type is a normal part of the body’s response to viral upper respiratory infection.

In the case of allergies, the immune system launches a similar attack against a harmless substance, such as pollen or dust. Because the body processes are so similar, the symptoms people experience with allergies often mimic those of a cold or infection. These include sneezing, congestion, watery eyes and fatigue.

Allergic reactions are caused when a person comes into contact with an allergy to which they are sensitive. The most common allergens include:

• Pollen. Given off seasonally by trees, grass and weeds, pollen is responsible for triggering most cases of allergic rhinitis (hay fever). The plant most commonly associated with pollen allergies is ragweed.
  

  

• Dust mites. Many people with dust allergies are actually allergic to dust mites – microscopic insects that live in dust. Like most airborne allergens, dust mites often trigger allergic rhinitis symptoms in sensitive people. People allergic to pollen, mold or animal dander (shed dead skin) may also experience symptoms when exposed to dust.
  
  
• Foods. Almost any food may cause an allergic reaction. However, only eight foods cause 90 percent of allergic reactions: soy, wheat, tree nuts, peanuts, milk, eggs, fish and shellfish. These reactions can range from mild to the severe and life-threatening anaphylactic shock.
  
  
• Animals. People with animal allergies have sensitive immune systems that react to harmless proteins in animal dander, saliva or urine. Allergies to furred or feathered animals are common especially among people with other allergies or asthma. From 15 to 30 percent of people with allergies have allergic reactions to cats or dogs, according to the Asthma and Allergy Foundation of America.
  
  
• Mold. Allergic reactions to mold can occur during all seasons. The spores are spread by both air and wind under both dry and humid conditions depending on the mold type. It is common for people to have mold allergy if they or another family member are allergic to pollen or animal dander.
  

  

• Latex. Allergies to latex products (e.g., balloons, rubber gloves, rubber balls, condoms) are caused by proteins in rubber tree sap. There are two different types of reaction to latex. The most common is a red and itchy rash (contact dermatitis) that breaks out where latex contacts skin. In some cases latex allergy may cause the intense allergic reaction anaphylaxis. Sometimes people with latex allergy also experience reactions to tropical fruits, nuts, avocado, raw potato, tomato or celery.
  
  
• Drug allergies. Allergies to medication can cause a variety of symptoms from hives to the severe breathing problems associated with anaphylactic shock. Drug allergies are different from side effects.
  
  
• Insect stings. Most insect stings are caused by bees, wasps, hornets, yellow-jackets and fire ants. These insects have venom that may act on the human circulatory system causing the blood vessels to dilate or become wider. People with allergies to insect venom may experience anaphylactic shock following a sting.

Allergies can affect anyone regardless of age, gender, race or socioeconomic factors. There is a link between heredity and the development of allergic disease. If both parents have allergies, their biological child has a 75 percent chance of developing allergies, according to the Asthma and Allergy Foundation of America. If one parent has allergies, the child’s chance of allergy development is 50 percent. However, parents and children do not necessarily share the same allergies.

It was once thought that people would, or could, outgrow allergies.  Although allergies may seem to spontaneously improve, in reality, it is believed that they become dormant and have the potential to return at a later time. There is a tendency for allergies to become less severe after age 40 and become more severe after age 60.

Other factors that may produce allergy symptoms are environmental irritants (e.g., smoke, perfume), hormones and stress.