An allergy is basically your immune system overdoing it. That may sound a bit too simple given all the problems that allergies cause, but that is really what an allergy is.
It makes sense when you consider that your immune system is designed to protect your body from being invaded and killed by bacteria, viruses, etc. Most people are not usually sick, so we know that the human immune system is strong enough to fight off the invaders most of the time. Since those invaders are everywhere, even in the air we breathe, the immune system must be a pretty powerful force. So it should come as no surprise that when that powerful force overdoes it, you are going to have problems.
What does “overdoing it” mean? It means that your immune system decides to treat something that is not an invader like it is an invader. As soon as your immune system recognizes the invader as foreign to your body (sometimes the term used for this kind of an invader is “non-self”), it tells (“activates’) specialized cells in the area to respond to the invader by engulfing (eating and digesting it) or releasing toxic chemicals that may directly destroy the invader or change the environment to recruit specialized cells from other parts of the body to join the fight! It’s a battle and the affected part of your body is the battle zone!
Those defensive chemicals and cells not only target the invader, but can cause the normal cells in the invaded area to swell, or itch or hurt, etc. That can be really annoying if the invaded neighborhood is your nose, because now you have to deal with sneezing, congestion, a runny nose, post-nasal drip or coughing. Sometimes you can even get sinus infections. If your body is actually under an attack by a serious invader (a bacteria or virus that would love to completely take over your body), it is worth having some of those symptoms/problems in order to get rid of the invader. On, the other hand, if your immune system responds like that to a harmless tree pollen, you’ve got a problem each Spring!
This type of scenario is called an allergic reaction, and it can effect several different parts of your body. While an allergic reaction in your nose (allergic rhinitis) is really inconvenient, an allergic reaction that involves your throat or lungs can stop you from breathing (because there is so much swelling that the air can’t get through) and can be fatal.
Things that are not planning to invade your body, but which your immune system can confuse with invaders are called allergens. They are the things that people become allergic to. Common and well known allergens are the pollen from trees, grass and weeds, dander from dogs and cats, dust (actually it’s the dust mite feces that people are actually allergic to!), poison ivy, mold, bee and wasp sting venom, and foods like peanuts and shell fish.
How did I get allergies?
Usually, your immune system needs at least one exposure to a potential allergen in order to decide that it is an invader which must be attacked in the future. Sometimes it takes hundreds of exposures before a person becomes allergic. Some substances are more likely to induce allergies than others (we don’t hear about people being allergic to sand, but lots of people are allergic to cats), and may take only one or just a few exposures to make a person allergic. That may be why some people say “Poison Ivy? I’m not allergic.” And then go out and get a rash from poison ivy. What happened is that they actually did touch poison ivy once or twice without getting a rash, and then those 1 or 2 exposures resulted in their immune systems deciding that poison ivy (technically the oil on the poison ivy leaves) is a potentially harmful invader that should be attacked. The next time they contact poison ivy and get the oil on their skin, their immune system attacks the oil, and the skin with the oil on it gets red and itchy and swollen.
Sometimes, someone reacts to a substance or food that they may never have been exposed to in the past. That happens when your immune system has decided that one allergen is an invader (That “decision” by the way, is called “sensitization”), and then gets exposed to another substance that looks the same (on a molecular level) as the allergen that you are already immune to. In that case, your immune system will treat the new substance like it is an invader even though you have not been exposed to it before. This is called a cross reaction. Common cross reactions include one between cherries and birch tree pollen allergens. Even though a cherry looks nothing like a birch tree or birch tree pollen to us, our immune system considers them to look so much alike on a molecular level that sometimes it will treat one like it is the other. That means that a little boy who lives in a house near woods with lots of birch trees and is allergic to birch tree pollen due to multiple exposures may get an allergic reaction the very first time he eats a cherry.
I thought I was too old to get allergies?
People tend to think of allergies as something that always starts in childhood. But that’s not really true. Allergies can start at virtually any age and can change in intensity. Some people have severe allergies in childhood and then grow out of them. Other people get allergy symptoms for the very first time when they are in their 30’s, 40’s, 50’s or later! So just because you’ve never had a problem with allergies doesn’t mean that this year’s Spring sneezing isn’t from an allergy. Once you have allergies, they may remain at a mild level or more progress over time to truly affect your quality of life.
Some allergic reactions are so mild that they are barely noticed or simply aren’t enough to make you take a medication or want to go to the doctor. Others are so severe that they make people take medications every day or miss work or require emergency treatment to stop them from being fatal.
Allergies can cause other problems
One thing worth considering with regard to allergies is that they can sometimes be the underlying cause of another problem. Some people who are prone to sinus infections (without other classic nose allergy symptoms) really just have an allergy which leads to inflammation in the sinuses which then leads to an infection. Other people have asthma with an allergic trigger, even though they don’t have the typical nose allergy symptoms.
If you think you have allergies, getting allergy testing may be the beginning of a solution!
When allergy medications and avoiding the things that you are allergic to don’t work, you may need to consider allergy shots. Also known as allergy immunotherapy, allergy shots are not just an injectable form of allergy medication. Rather than providing a medication to suppress allergy symptoms, allergy injections actually contain the very substances that you are allergic to! But, because they are entering your body in a different way (through your skin rather than through your airway), your body learns to respond to them in a different way. In most cases, that means that your allergies decrease or disappear.
At first, you need the shot/s every week, but after a few months, this will typically decrease to every other week, with the eventual goal of having the shots be only monthly. After two years of shots you are re-tested to see if the shots have resolved the allergies or if your allergies have changed in some other way. Our hope is that the 2-year repeat test will show that you know longer have allergies and that you will be symptom free without medications or shots!