Updated: Jul 3, 2018
Why it's the first line of treatment in severe reactions and you should always have it with you
If you're like me, the idea of jabbing my baby with a huge needle was terrifying.
But it's critical to understand that epinephrine is actually the first line of defense in anaphylaxis. And the timing is critical, because it is more effective the earlier that it is given. In fact, a significant number of cases where allergic reactions resulted in death were often due to the delayed use (or none at all) of epinephrine.
For me, what was helpful and gave me more confidence and comfort in using it was getting educated on what exactly epinephrine did and why it worked. So in this post, I'll attempt to demystify what it is and distill down what I've learned along the way.
So why does epinephrine work, and how is it different from Benadryl? It may help by first understanding what is happening in the body when an allergic reaction happens.
What's happening during an allergic reaction
Under normal circumstances, when a body naturally detects something that is foreign or harmful, the body's immune response is to release histamines, which then signal the body to bring blood to that area. The reason it tries to do that is because blood carries immune cells, which can help fight it off.
Food allergies are an abnormality in the sense that the body is mistakenly identifying certain food as harmful. What happens is that the allergens triggers that blood flow, which manifests itself in what we see as an allergic reaction, such as hives, rashes, swelling, etc.
So in mild reactions, the body first starts by releasing histamines. This is why Benadryl can help when it's mild. Benadryl is an anti-histamine, so it blocks those signals, and thus "prevents" the blood flow going to those areas.
However, in the case of severe reactions, the body is identifying the allergen as something so harmful to the body that the response goes completely haywire and things start cascading rapidly. This is known as anaphylaxis, where you can find the signs and symptoms in my previous post. In those reactions, Benadryl cannot help - it doesn't make sense to try to block the response when the body has already responded and gone way past that point. To make an analogy of it, it would be trying to cool down a pot of boiling water with a drop of cold water. It doesn't make sense at that point.
The significant increase in blood flow can then result in intense swelling that can close up the throat. And because of that blood flow, it results in a drop in blood pressure everywhere else, which can begin to induce organ failure. At that point, it is known as anaphylactic shock.
So why does epinephrine help?
Epinephrine activates the fight-or-flight response in our bodies. The fight-or-flight response is an actual physiological reaction where it helps the heart pump stronger and constricts the blood vessels so that the blood is going to the critical places to stay alive, like the lungs and heart.
This has the effect of working against anaphylaxis. By constricting the blood vessels, it makes the swelling go down, which can open back up the throat. It is also directing the blood back to the vital organs, to buy some time to help keep the person alive.
However, it's critical to understand that it is more effective the earlier it is given. You can think of the reaction like a cascade effect of all the different responses. Or, if you are the visual type, an analogy would be like the snowball effect:
Anaphylaxis usually has a slower initial build, like at the top of the hill - though "slow" is very relative and can actually happen very quickly. For some people, it may be a couple hours; but for others, it could be a matter of minutes. As you can see, if epinephrine is given early on, it will be much more effective. As it gets later and especially once it really builds momentum, epinephrine may no longer be effective.
A few additional points:
- There are very few side effects to epinephrine. The benefits overwhelmingly outweigh any little risks. (The side effects are an increased heartrate and energy level, that will go back down after a couple hours - well worth the benefit of saving one's life.)
- Sometimes, a second epi-pen may be needed, as the reaction can come back.
Always call 911 when the epi-pen is given
On that last point, it's important to get to the hospital anytime you give the epi-pen. This is not because the epi-pen was dangerous, but because any reaction that requires the epi-pen will require observation in case MORE medication is needed.
Usually, a steroid will be required to hold off the reaction. But steroids take time to start working, so it's important to have enough epinephrine while waiting for steroids to kick in. As mentioned, severe reactions can come back when the epinephrine wears off. Being in the hospital ensures that you can get the medication that is needed.
We've also found it more helpful to call 911 because then you bypass the waiting room in the ER. However, the gist of it is that it's important to get to the hospital as soon as you can.
So to recap:
- Benadryl can be used in mild reactions
- However, epinephrine is the FIRST LINE OF DEFENSE in the case of suspected anaphylaxis and there is no harm in using it
- Epinephrine is more effective the earlier it is given
- Be aware that you may need more than one epi-pen, as the reaction can be biphasic
- Get yourself to a hospital if the reaction was severe enough to warrant epi-pen use
- And of course: PRACTICE using the epi-pen so that you know exactly what to do when the time comes. Here are some links to great tutorials on how to use the most common epinephrine autoinjectors: Epi-pen, Auvi-Q, Adrenaclick
Note: The above is NOT a substitute for professional medical advice and is meant to be just one perspective. ALWAYS consult and seek the advice of your doctor before acting on anything.