by Rob Lamberts, MD
Last week I discussed seasonal allergies and the condition called allergic rhinitis, in which pollen, a substance that is not at all a threat to the body, is mistaken for something that is dangerous. As the immune system mistakenly defends us from pollen, it releases substances make us sneeze, itch, and basically feel lousy.
But some allergies are much more than a nuisance; they can kill. Imagine what would happen if the armed forces suddenly thought all men named Larry within our borders were dangerous and so started raiding New Jersey, bombing Idaho, or sending paratroopers to capture Amarillo, Texas. The consequences of such a mistake would be a threat to the country, and likewise the consequences of the mistaken allergic response can also be life-threatening.
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Why are Allergies Getting Worse?
Before discussing the specific allergies, I need to back up and answer a question that we discussed on Facebook: Why are allergies are getting worse? Scientific data supports the fact that more people are having allergies, and these levels are increasing over time. Why, in a world where we are more clean and sterile, where we are exposed to less serious disease than ever in human history, are our immune systems getting confused and attacking things that aren’t even a threat?
One of the most popular theories as to why allergies are on the rise is the hygiene hypothesis, which suggests that the relative sterility of our environment is causing worse allergies. It seems that we are not keeping our immune systems busy enough and so they are inventing things to do. Evidence supporting this theory includes:
Immigrants from developing countries see a sharp rise in allergies when coming to industrialized countries
Children in larger families have less allergies than do only children
People with certain parasitic infections have a much lower rate of allergies and asthma (A very interesting episode of This American Life describes a man who was cured of severe allergies by getting a hookworm infection on purpose!)
So am I suggesting that we should imitate that gross guy at work who doesn’t believe in hygiene? No, but I am suggesting that perhaps our obsession with avoiding all germs is extreme.
What Is Anaphylaxis?
The most serious and potentially life-threatening allergic reaction is a condition known as anaphylaxis. Anaphylaxis happens when an allergen is recognized by antibodies, which you’ll recall from last week’s article are special proteins in the body that recognize invaders. When antibodies mistakenly identify a normally benign substance—like peanuts-- as an invader in the body, the antibodies immediately combine with certain white blood cells, releasing histamine and other substances that have a profound effect on the body.
What Are the Symptoms of Anaphylaxis?
The first symptom of anaphylaxis is something doctors call urticaria. Urticaria are red itchy spots over the body, and are more commonly known as hives. Hives alone are not a sign of serious allergy; in fact they are a very common condition caused by allergies and even viruses. It is the presence of the other symptoms that not only define anaphylaxis, but make it deadly. These symptoms include:
Breathing difficulties, caused by the narrowing of the passages that bring air to the lungs. Shortness of breath and wheezing are the most common symptoms of anaphylaxis.
Digestive symptoms, such as abdominal pain, vomiting, and diarrhea.
Shock, which is a sudden drop in blood pressure caused by the substances released by the white blood cells.
What Causes Anaphylaxis?
Unless they get immediate help, people having an anaphylactic reaction can die. The allergens that are most notorious for anaphylaxis include:
Insect stings - most commonly from insects related to bees
Certain foods - including peanuts, shellfish, and eggs
Medications - antibiotics are the main culprit, but many other medications can also cause anaphylaxis
Latex - which previously had widespread use in hospitals and doctors’ offices
Another Serious Type of Allergic Reaction: Delayed Hypersensitivity
People with delayed allergic reactions are not at increased risk of having anaphylaxis.
There is a second type of allergic reaction that can have serious consequences, known as delayed hypersensitivity. The delayed immune reaction shows up as a local reaction of redness and swelling. The reaction doesn’t happen for hours after initial exposure, peaking 48-72 hours afterwards. Poison ivy is an example of that kind of reaction.
This type of reaction is usually not serious, but it can cause problems if the exposure happens in the neck or other critical areas.
What Causes Delayed Allergic Reactions?
Insect bites or stings often can cause a delayed reaction, with prolonged redness and significant swelling at the site of the sting. The good news is that people with delayed allergic reactions are not at increased risk of having anaphylaxis. If your arm swells up significantly after a bee sting, it does not mean you are in danger.
How to Live with Serious Allergies
So if what should you do if you think you have a serious allergy? Here are my quick and dirty tips for dealing with bad allergies:
Get tested: Know what you are allergic to. Allergy testing can determine what exactly what you should avoid, and may give a means for treatment. Bee sting allergy, for example, can be reduced or eliminated by getting allergy injections (as I described in my last article). Latex allergy can go undiagnosed for years without testing.
Get educated: Food allergies can be very hard to deal with. Peanut oil, eggs, and even shellfish can be hidden in many foods you may be served. Know what you should avoid and be on your guard for them. Latex can also be hard to avoid, so knowing what objects are made of it could save your life.
With drug allergies, you should make sure your doctor and pharmacist not only know your allergies, but the exact kind of allergic reaction you experience. Getting an upset stomach and diarrhea, or even a rash from an antibiotic, may not mean you should avoid the drug 100% of the time. But people who have had anaphylaxis from something like penicillin should avoid not only penicillin, but also antibiotics related to it.
Be prepared: People who have had a serious allergic reaction should wear something alerting others to their allergy. They should also carry an Epi-Pen, which is a device that injects the person with epinephrine. Epinephrine temporary counters the immediate threats of shock and breathing difficulties, giving the person time to get to the emergency room and get more aggressive care.
If you have family members with a serious allergy, you should also educate yourself about how to use an Epi-Pen and how to react to a serious allergic reaction.
Let me once again remind you that this podcast is for informational purposes only. My goal is to add to your medical knowledge and translate some of the weird medical stuff you hear, so when you do go to your doctor, your visits will be more fruitful. I don’t intend to replace your doctor; he or she is the one you should always consult about your own medical condition.
Catch you next time! Stay Healthy!