What’s so bad about allergens that your body would rather kill you than let them enter?

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I know allergies are really common, but I don’t quite understand what’s so bad about pollen, peanuts, etc. that you body would rather shut down your airways entirely than let them enter. What exactly would happen if they did get in?

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I think that it is more that your body responds BECAUSE they entered your body than to prevent them from entering your body.

Your question assumes is that your body is expressing a preference. It is not.

If you understand allergies, think of it as a mutation that is not desirable.

Allergies are an abnormal excessive response to proteins that are attacked by your body.

There is no intention to harm the body.

Your body has defenses against stuff. In the most simplistic terms: first it identifies a threat, then it takes it out.

Stuff enters your body all the time. Sometimes it’s food, sometimes it’s viruses, sometimes it’s bacteria, sometimes it’s mold, sometimes it’s cancer cells, sometimes it’s other junk like dust or fiber or pollen.

When harmful stuff gets in, and it starts damaging your system, the white blood cells get to work destroying it. Some set things on fire (histamine and inflammation) and call in the troops. Some assassinate the cells that are harboring the baddies. Some eat the baddies up (macrophages).

**Your immune system finds out what’s a threat through trial and error.**

Often this is good – the flu builds a home in your cells, then you build antibodies to the flu to wipe it out and your system remembers what the flu looks like to mount a response again later before it gets too cozy.

Sometimes this process goes awry – pollen, food proteins, or your own cells can look like threats and set off the white blood cells to come destroy everything to get rid of it.

The histamine response is basically locally setting everything on fire when a threat is detected. Great for wiping out bacteria and viruses. Awful when it’s something stupid like pollen or tree nuts (allergies) or your own cells (autoimmune disease). But your immune system, as effective as it is, doesn’t know the difference.

An allergy is an immune system response to a non threat. It’s an error. There is nothing bad about what it is reacting to, it’s just reacting to it as if it is.

Scientists theorise that they happen because the immune system over a long time of evolution has been selected to slightly overreact than underreact. This is because underreacting in the past would have resulted in death and death is bad. It does though mean that in some people it’ll overreact so much that it will kill them. However, in most people it’s just a slight annoyance. Being slightly annoyed doesn’t prevent you from breeding and so it won.

Remember, evolution isn’t about perfection, it’s about good enough with what it has to work with.

>don’t quite understand what’s so bad about pollen, peanuts, etc.

Nothing is bad about them. Allergies are like your immune system having a phobia – extreme fear and over-reaction to something that’s *not actually a threat* at all.

>What exactly would happen if they did get in?

Again, nothing. For proof of this, what happens when non-allergic people eat peanuts or breathe pollen? Nothing. That’s “what would happen if they got in.”

Allergies are your immune system *making a mistake*, and launching a “get this out at ALL COSTS” reaction against a completely harmless thing.

Allergens are simply things that your body reacts to that objectively by our standards it shouldn’t.

Seasonal allergies, or nose symptoms typically, occur when these allergens get in your nose. Your body reacts to their presence locally causing swelling and mucous production.

Anaphylactic type reactions occur when an allergen gets into your bloodstream. This causes a massive immune response. Part of the immune response is to open up your blood vessels to increase blood flow to certain areas. This is done to bring in cells to clean up the problem. However if this happens in your entire body it rapidly drops your blood pressure. It also can cause fluid buildup in the area near the top of your windpipe which can pinch off the airway. As well your airways themselves begin to close as that’s part of the response.

Basically allergens activate your immune system and if that happens to much at once, it kills you.

This is one of those things that reminds us that “intelligent design“ definitely wasn’t involved in making us. Unless you call it “trial and error“. With lots of quick fixes slapped in! Things that work on one occasion turn out to destroy you on another!

It’s a false alarm.

For some people, certain things are basically mistaken for various kinds of bad stuff. Essentially these random things enter your body and pull the fire alarm like a kid pranking his school.

The danger isnt real, but the responce is very, VERY real. Imagine if the fire trucks arrive and the fire chief (your immune system) is just unreasonably ADAMANT that there is a fire and he will stop at nothing to find it. For days on end he keeps calling in more fire engines and school is just straight up cancelled for days, eventually the hoses come on and rooms get cleared out, the library is a pile of mushy papier-mache and the office is waterlogged to hell.

Your immune system once set off will wreak havoc in the absence of an actual target, and in the meantime the real culprit is sneakily stewing in your stomach or your nose, going unnoticed, with their hand constantly yanking on the damn alarm over and over.

It’s a false alarm.

For some people, certain things are basically mistaken for various kinds of bad stuff. Essentially these random things enter your body and pull the fire alarm like a kid pranking his school.

The danger isnt real, but the responce is very, VERY real. Imagine if the fire trucks arrive and the fire chief (your immune system) is just unreasonably ADAMANT that there is a fire and he will stop at nothing to find it. For days on end he keeps calling in more fire engines and school is just straight up cancelled for days, eventually the hoses come on and rooms get cleared out, the library is a pile of mushy papier-mache and the office is waterlogged to hell.

Your immune system once set off will wreak havoc in the absence of an actual target, and in the meantime the real culprit is sneakily stewing in your stomach or your nose, going unnoticed, with their hand constantly yanking on the damn alarm over and over.

Nothing. Allergens we commonly refer to are generally harmless from a biological standpoint.

The problem with allergens is that your body’s defense systems have for one reason or another has classified it as intensely hazardous and deserving of immediate and aggressive defense.

If the body has a high enough sensitivity or if you have enough of the substance in your system, your body pushes your responses into hazardous levels, the same way a fever that’s supposed to fight infection can reach temperatures harmful to the body. This is the anaphylaxis response we see: Your body pushes so hard to defend against the allergen that the response overwhelms normal functions and you need medical intervention to force it to back down before it kills you.

I’ve noticed some allergies in my family being related to influenza or others that cause fevers. As an adult my Dad became allergic to his male cat while having the flu for 3 weeks. My son became allergic to ibuprofen around 5 years. I became allergic to rats after working with them for 3 years. Some but not all allergies may be from a novel chemical in your body during infection and immune programming.

In each case above I know there was a fever involved.