Woman blowing her nose outside with a tree in bloom.
Lou Romig, MD
Our immune systems play the biggest role in causing allergic reactions. To be honest, we don’t really know why people have environmental/seasonal allergies but there’s a very interesting theory proposed by allergy researchers. The Hygiene Hypothesis speculates that the very young immune system is primed to recognize and defend against substances or organisms that are potentially harmful to the body, especially parasites and bacteria.
In undeveloped countries and rural areas where children spend more time in the dirt and around animals, environmental allergies are very uncommon. It’s thought that this is because the immune system is being exposed to the triggers it’s “programmed” to fight against to protect the body.
If the immature immune system isn’t exposed to those triggers, it’s still ready to fight, so other triggers start to set it off. This is demonstrated by the fact that in developed countries, where there is good hygiene and little exposure to parasites and environmental bacteria, there is a much higher rate of environmental allergies.
Essentially, our sterile, sealed, hygienic world makes our immune systems respond to triggers that aren’t inherently harmful to us because they’re not exposed to as many triggers that are harmful. It is the immune system’s recognition of, and reaction to, these environmental triggers as “enemy” instead of “friend” that gives us the symptoms that make us so miserable and are at times even dangerous.
1) People are born with allergies – Fiction
Although certain types of allergies tend to run in families (especially foods and medications), most allergies show up after people have been exposed over and over to the things they eventually become allergic to.
Allergies may be developing and cause no symptoms, or very low-level symptoms, for years and then suddenly reach a point where the immune system reacts vigorously, causing the commonly recognized symptoms. Allergies may show up at any time in life, even after years of frequent and harmless exposure to the offending substance.
2) You can grow out of your allergies – Fact (sort of)
Some allergies can seem to go away over a period of years, BUT there’s always a risk that those allergies will come back later in life.
3) If you take your allergy medicines, your allergies shouldn’t bother you – Fiction
Your symptoms often depend on how much exposure you’re getting to what you’re allergic to. Sometimes there’s so much allergen (the triggering substance) out there that the medications just can’t keep up. Also, your reactions to the allergen might change, so you might have to add a new medication such as eye drops or nasal steroid spray.
Although it’s unclear whether someone can develop resistance to an allergy medication they’ve used for a long time, sometimes switching to a different version of the same type of medication can help. For example, if you’ve been taking Claritin (loratadine) for a long time you might want to try Zyrtec (cetirizine). By the way, the generic versions of most nonprescription allergy medications work as well as the brand name medications.
Finally, if your allergy medications don’t seem to be working as well as usual, consider doing more to avoid your triggers.
4) You should only take your allergy medicine when you’re having symptoms – Fiction
If you know you have seasonal allergies or other allergies that are predictable as to when or where they might occur (like being exposed to a cat at a friend’s house), it’s better to start your medications before you start having symptoms.
For seasonal allergies, take them every day as long as the triggers are in your environment. Prevention of the symptoms is more effective than treating them once they’ve started. This might mean taking allergy medicine every day for months at a time. The medicines commonly used for this are considered safe for both adults and children when used as directed.
5) People with dog allergies can get “hypoallergenic dogs” so they won’t have any problems with their allergies – Fiction
There’s no such thing as a 100% hypoallergenic dog or cat, even one without fur or hair. It’s not the fur or hair that causes allergic reactions; it’s the dead skin cells and chemicals in the saliva and other secretions that cause trouble.
Hypoallergenic dogs and cats may be somewhat less likely to cause allergic reactions, but there’s no guarantee that they’ll cause no reaction at all. Puppy kisses can be sweet and a lot of fun, but only until the allergy symptoms kick in.
6) Having cats and dogs around very young children makes the children more likely to develop allergies – Fiction
Exposure to dogs and cats within the first 2 years of life actually helps prevent the development of allergies, not only to the animals, but also to other environmental triggers. The thought is they help the developing immune system recognize benign environmental triggers as “friend” instead of “enemy”. See the Hygiene Hypothesis above.