The public and mass media use the term “allergy” loosely. Without a clear definition, a lot of confusion and miscommunication can result. From a medical and scientific perspective, allergy is a condition in which the immune system reacts to something in the environment that is harmless.

The human immune system is an incredible thing. Its job is primarily to protect the human body from infections. You can imagine the immune system as the defense department of the body. When the body is under siege by microbes, the immune system sends out microscopic troops to ward off an invasion. Without an intact immune system, human beings would be constantly threatened by various infections.

However, having a large army of elite troops can be a double-edged sword. Sometimes the armed forces sound a false alarm and respond to an innocuous material from the environment. This response could be a localized mobilization, or it could be a full-scale assault on a nonexistent enemy. When the immune system reacts inappropriately to a benign target, the body experiences an allergic reaction.

While the topic of allergy is broad and encompasses skin allergies, asthma, hay fever, and other less common conditions, the discussion in this chapter is limited to nasal allergies and reaction to food or chemicals. It is worth mentioning here that skin allergy (commonly known as eczema), nasal allergy, and asthma are closely related conditions. These three conditions are all caused by an overactive immune system, and they tend to run within the same family. If Uncle Bob has nasal allergy and Grandpa has asthma, your child may be cursed with eczema. They are all really different manifestations of the same hypersensitive immune system.

Popular Misconceptions of Allergy

The nonmedical community often uses the word “allergy” to mean a variety of reactions to environmental exposures. For example, a lot of people believe that they are “allergic” to milk because they experience bloating, stomachache, and diarrhea after consuming dairy products. Others claim that their child is “allergic” to juice because she develops diarrhea after consuming a large quantity of it. Neither of these situations describes a true allergic condition because neither reaction involves the immune system.

In the first scenario, the reaction to dairy products described is most commonly due to lactose intolerance. These individuals lack the ability to digest the sugar in milk, so every time they consume any dairy product, the large amount of undigested sugar inside their intestine triggers a bunch of unpleasant feelings. This reaction involves the digestive system, not the immune system. In the second case, drinking excessive fruit juices overwhelms the intestine with sugar. Once again, this undigested sugar wreaks havoc in the body.

Unfortunately, the industry is quick to take advantage of these common misconceptions. They make lactose-free formula for babies who are allegedly “allergic” to milk, when in fact most of these babies have run-of-the-mill baby reflux. The lactose-free formula makes absolutely no difference in these babies' symptoms. Of course, these specialized formulas cost more than the regular kind, and anxious parents who purchase these special formulas spend more than they need to in the false belief they are doing more to keep their child healthy.

Allergy to Cigarette Smoke

Many people avoid cigarette smoke because they think they are allergic to it. Even though this is not really true, it isn't a bad idea after all. Secondhand smoke is extremely dangerous and toxic. Even though smoke from cigars and cigarettes cannot trigger an allergic reaction in people, everyone should avoid it like the plague. When people experience a burning sensation in their nose and eyes in the vicinity of smokers, they are being irritated by the microscopic smoke particles. This reaction does not involve the immune system, so it is not considered an allergic reaction.