Would benadryl help anaphylaxis any?

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Alpiner

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Your 6 miles in the woods hiking with some buddies with no cell signal when one of your buddies gets stung by a bee, tells you he is deathly allergic and isn't carrying epi. Your other friends leave to go get help while you stay with your buddy who is showing signs of anaphylaxis. You have a basic first aid kit with a few medications that includes antihistamine pills. What do you do?

I understand that people face palm the idea that anyone would consider benadryl for anaphylaxis because ultimately they need epi but in a situation where epi isn't an option would nothing be better than benadryl?
 
Histamine blockade is still helpful in treatment of anaphylaxis, even when epinephrine is needed for immediate symptom relief of bronchospasm, hypotension, and edema.

Preventing further progression by at least attempting to block H1 mediation of continuing symptoms is certainly better than nothing. If you have IM or IV Benadryl, I would administer that in place of PO. If PO Benadryl is all you have, go for it.
 
What about dosing in this situation? Presumably we want to go higher than the standard dosage which is aimed more at hay fever and whatnot? Antihistamines have a pretty wide therapeutic index, I think... Depending on how deathly allergic he is, maybe have him take 5x the recommended dose on the package?

If all we have is PO, does it make sense to have him chew the tablets up for faster absorption?
 
Whats the regular dose of Benadryl PO? How much can be safely given in this type of situation? Is the airway compromised and does he have the ability to swallow? If so you can always absorb the medication through the gums, kinda like nicotine and glucose. Not really optimal but it sounds like a **** sandwich and you have to take a bite.
 
If you exceed 50mg of a first gen like benadryl you'll start to see anticholinergic effects. You achieve histamine blockade with 1-2mg/kg but really you never dose more than 50mg whether IV, IM, or PO.

The problem with benadryl is its speed of action and its delivery. We are talking about a drug that reaches peak effect in an hour, not a minute. If you don't have IM/IV, you have PO. You are on the right track with increasing absorption, but think elixir to drink vs aiming for absorption across mucous membranes. Think more along the lines of breaking open a capsule and mixing in water to drink vs chewing (I suggest you try chewing diphenhydramine... you will make your patient puke).

If they are already compromising their airway, it is unlikely they can take PO.

In a true anaphylaxis emergency, we want to treat with drugs that work along multiple timelines and mechanisms: IM epi, nebulized albuterol, histamine blocker, corticosteroid.

If it was just me and my friend, and they got stung on an extremity, and it was that desperate mortal situation, I'd consider a tourniquet to buy time... but there is little evidence that works (just a "good idea" some Dr had that I read somewhere once).

Your friend should have brought an epi pen, because there are better screwball tricks with an epi-pen (getting an extra dose) than trying to get someone to chew up benadryl in desperation.
 
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If all we have is a box of pills, is it a ridiculous thought to try crushing them up and having him snort them? A quick google search shows that lots of people do that for fun...

If we're in the situation where he can still take PO, do we have to consider first-pass metabolism? Are we really that worried about anticholinergic side effects? If he weighs 100kg, are you still giving only 50mg PO?
 
The body should release some adrenaline on it's own which made me think, would calming him down be a bad idea compared to him being fearful which (I think) causes more epinephrine to be released?
 
Alpiner said:
The body should release some adrenaline on it's own which made me think, would calming him down be a bad idea compared to him being fearful which (I think) causes more epinephrine to be released?
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Itching, swelling, feeling generally terrible, and not being able to breathe is stressful enough.

Like many other chemicals that are produced intrinsically, the level of epinephrine in the blood is regulated by the nervous system and you will see diminishing returns w/ increased stress.
 
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Alpiner said:
The body should release some adrenaline on it's own which made me think, would calming him down be a bad idea compared to him being fearful which (I think) causes more epinephrine to be released?
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Hang him over a cliff by his ankles...or tell him there is a bear stalking him :D
 
Flying said:
Itching, swelling, feeling generally terrible, and not being able to breathe is stressful enough.

Like many other chemicals that are produced intrinsically, the level of epinephrine in the blood is regulated by the nervous system and you will see diminishing returns w/ increased stress.
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I am wrong, epinephrine does not self-regulate. We don't release enough of it quickly enough to counteract symptoms.

Anyways, freaking someone out to the point where they can relieve symptoms related to anaphylaxis will cause more problems than its worth. That sounds like something Dr. House will do.
 
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Gurby said:
If all we have is a box of pills, is it a ridiculous thought to try crushing them up and having him snort them? A quick google search shows that lots of people do that for fun...

If we're in the situation where he can still take PO, do we have to consider first-pass metabolism? Are we really that worried about anticholinergic side effects? If he weighs 100kg, are you still giving only 50mg PO?
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The issue is that H1 blockers like diphenhydramine are adjuncts and largely provide relief for uticaria and other annoying symptoms vs being major lifesavers. 100mg is given sometimes in anaphylaxis, but not usually. You'd be better off giving ranitidine or some other H2 blocker in addition to your 50mg of diphenhydramine vs giving 100mg of diphenhydramine. Diphenhydramine is noncritical enough that they might do RCTs with it. Diphenhydramine isn't going to solve your upper or lower airway issues. It isn't going to fix shock. 100mg would likely generate adverse effects in the course of achieving minor symptomatic relief. If all you have is PO, you can give PO cetirizine and get the same benefit... and then you won't have the sedating or psychomotor affects that some people get with diphenhydramine. Actually some people have anticholinergic effects at very low doses, probably 5-10% of people will get amped up 25-50mg benadyrl instead of sleepy.

If you asked me for my first three choices of drugs to have available to treat of anaphylaxis, it would be: 1. Epi 2. Albuterol 3. Glucagon
 
A little late to the party but, my second job is as a wilderness trip leader taking teens out on 3-7 week expeditions. We carry epi, bendryl, and prednisone for anaphylaxis. We follow WMA's field protocols (available at: https://www.wildmed.com/wp-content/uploads/2013/10/wma-field-protocols.pdf anaphylaxis is page 2).

The TLDR is that after recognizing anaphylaxis we administer .3mg 1:1000 epi IM (essentially an epi pen but we syringes), 50mg of diphenhydramine every 4-6 hours, normally administer prednisone as well and evacuate asap. Its protocol we've used before and it seems to work. My understanding is that the statistical chances of a severe anaphylactic reaction are fairly low and that a system but not life threatening reaction is far far more common.

Unfortunately some organizations aren't able to get prescriptions for epi so they can only use the benedryl. It become a growing issue. You can learn a little more about the fractured avalibility of epi and the fight to bring it to the backcountry at https://www.outdoored.com/articles/epinephrine-medical-ethical-necessity-or-legal-nightmare
 
DavidM said:
A little late to the party but, my second job is as a wilderness trip leader taking teens out on 3-7 week expeditions. We carry epi, bendryl, and prednisone for anaphylaxis. We follow WMA's field protocols (available at: https://www.wildmed.com/wp-content/uploads/2013/10/wma-field-protocols.pdf anaphylaxis is page 2).

The TLDR is that after recognizing anaphylaxis we administer .3mg 1:1000 epi IM (essentially an epi pen but we syringes), 50mg of diphenhydramine every 4-6 hours, normally administer prednisone as well and evacuate asap. Its protocol we've used before and it seems to work. My understanding is that the statistical chances of a severe anaphylactic reaction are fairly low and that a system but not life threatening reaction is far far more common.

Unfortunately some organizations aren't able to get prescriptions for epi so they can only use the benedryl. It become a growing issue. You can learn a little more about the fractured avalibility of epi and the fight to bring it to the backcountry at https://www.outdoored.com/articles/epinephrine-medical-ethical-necessity-or-legal-nightmare
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Aren't EMTs prohibited from giving any OTC medications?
 
GloriousGabe said:
Aren't EMTs prohibited from giving any OTC medications?
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Our protocols allow for all OTC medications provided they are given for their labelled use.
 
Tigger said:
Our protocols allow for all OTC medications provided they are given for their labelled use.
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Really? I thought that was strictly in the domain of a nurse and that EMTs can only do what is allowed under state law and they have protocols for (NTG, ASA, Albuterol, etc). Are you saying EMTs can dispense an OTC provided there is a label on it with their name?
 
I think a lot depends on the local services EMSA rules plus what the local medical director has decided what he wants his/her EMTs to be able todo/not do etc.

Also, correct me if im wrong, but my understanding is that a lot of SAR teams actually operate under Good Samaritan laws if they're not affiliated with the local EMS service?
 
Jim37F said:
I think a lot depends on the local services EMSA rules plus what the local medical director has decided what he wants his/her EMTs to be able todo/not do etc.
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What's an EMSA?

Also, correct me if im wrong, but my understanding is that a lot of SAR teams actually operate under Good Samaritan laws if they're not affiliated with the local EMS service?
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Correct. I'm on a SAR but we have no medical director at all. If/when we find a lost person who needs medical help I suddenly transform from a SAR member to an EMT-who-happens-to-be-off-duty-but-in-the-right-place-at-the-right-time.
 
GloriousGabe said:
What's an EMSA?


Correct. I'm on a SAR but we have no medical director at all. If/when we find a lost person who needs medical help I suddenly transform from a SAR member to an EMT-who-happens-to-be-off-duty-but-in-the-right-place-at-the-right-time.
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EMSA= Emergency Medical Service Authority. Also known as LEMSA (Local EMSA). Not every state has "state wide protocols". In states like TX their medical director can have EMT or medics do what ever they please. So if their medical director wants EMT to start IOs and intubate then they are given those skills (obviously with additional training).
 
GloriousGabe said:
Are you saying EMTs can dispense an OTC provided there is a label on it with their name?
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Not if it has their name one it. OTC medications don't have names as they are not prescribed. Labeled purpose means the mediation is given for what it treats. If the OTC medication is for allergies then they can only give it for allergy related complaints.
 
GloriousGabe said:
Really? I thought that was strictly in the domain of a nurse and that EMTs can only do what is allowed under state law and they have protocols for (NTG, ASA, Albuterol, etc). Are you saying EMTs can dispense an OTC provided there is a label on it with their name?
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No...he's saying that as long as the otc medication is being administered per "it's label" (and is the patient's owned)

EMTs can assist a patient in having them take their own medication. If the truck has a bottle of OTC ibuprofen; however, they could not. (Typically, that is).
 
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