General Question

Snoopy's avatar

Tagamet/Zantac for wasp/yellow jacket stings?

Asked by Snoopy (5788points) September 8th, 2008

I was stung by some little #@&! about 24 hours ago. The area is red, hot, swollen and painful and measures about 14×10 inches on my thigh. I have taken Claritin (H1 blocker) and Advil….was told to add above (H2 blocker). What is the physiology explaining the addition of this medication? I realize that H1 and H2 are both histamine receptors. I cannot find the exact mechanism of action explaining how an H2 blocker will help w/ symptoms typically associated w/ H1 receptors. Thoughts?

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17 Answers

scamp's avatar

What did your doctor say?

drhat77's avatar

BEAT IT, shilolo! (he always starts answering after i do, and gives a much better answer)

drhat77's avatar

chemical receptors in the body are not perfect “lock and key” situations like text books sometimes picture them. sometimes a chemical key that is “close enough” can be jammed in the lock and make it work, especially if in high enough doses. This allows a H2 blocker, taken in high enough doses, to give some extra H1 blocking activity. But usually it is not first line, or given by itself, because it is not as strong as a H1 blocker. so it is given in addtition to benadryl, etc.

syz's avatar

Awwww, you yelled at shilolo :(

Snoopy's avatar

Fabulous, Dr Hat. I have been searching all afternoon for an answer. I just kept seeing the directive to take the secondary medication, w/out explanation.

(You should also know that I sent the Q to Shilo….I wasn’t aware of your presence in the collective….thanks so much!)

Snoopy's avatar

@Dr hat. Since you did so swimmingly well w/ the tagamet portion…..why the suggestion for a tetanus shot? Is that something inherent to stinging insects?

drhat77's avatar

the only reason drugs work at all is because they are “close enough” to fit into receptors in cells, but different enough to be broken down slower, or stay on the receptor longer. If only perfect lock and key situations occured, big pharma would be pan-handling on the street

drhat77's avatar

when was your last tetanus shot? i’m an ER doc, and i usually give a tetanus booster for ANYTHING that borke the skin if you are 10 years past your last one, and 5 years past your last one for a major injury that breaks the skin.

Snoopy's avatar

I haven’t a clue when my last one was…...isn’t getting a tetanus shot for anything that broke the skin, kind of like carpet bombing/overkill?

I can understand if I was actually sitting in the ER….why not? But to make a special appointment, co-pay, time, etc. etc.?

Snoopy's avatar

And one last thing….Isn’t a true allergy one in which there is an exposure and then subsequent exposure yields anaphylaxis?

If so, what would you qualify my rxn to this sting? If my husband were stung I guarantee he wouldn’t have a rxn much larger than a typical mosquito bite. Why am I so lucky?

scamp's avatar

My ex husband swelled a little more each time he was stung. He never had anaphylaxis symptoms, but was told that if she should get stung again, he should go to the ER to be on the safe side. I’d rather err on the side of caution. I hope your symptoms subside soon.

Snoopy's avatar

@scamp. Thanks. The bummer is that you don’t even get the satisfaction of knowing the little devil died stinging you like you do w/ bees…...He is still out there…..somewhere….Grrrrr.

shilolo's avatar

Kudos drhat. You may have won this battle…

All kidding aside, I might have treated things a bit differently. Firstly, claritin (or loratidine) is a weaker H1 blocker than diphenhydramine (benadryl). People tend to prefer claritin (and its cousins) because they are non-sedating, but, for a severe allergic reaction, I would want the more potent agent, which is diphenhydramine.

I hope you feel better.

Secondly, the addition of an H2 blocker will provide minimal benefit, at best. Most of the symptoms associated with allergic reactions, such as the itching and the swelling are due to the effect of histamine (released by mast cells) on H1 receptors. Even though an H2 blocker might cross react with an H1 receptor, the affinity is very low, and thus you get very little added benefit.

If you were my patient, and your reaction were as severe as you described, I would have added (to benadryl, not claritin) an oral steroid medication. It would take longer to work (i.e. 6–8 hours), but it would reduce the inflammation by suppressing the activity of T-cells and mast cells (thus less histamine release). Here we would expect a 1–2 punch. The antihistamine blocks the effects of the already-released histamine, while the steroid prevents more histamine from being released.

I hope you feel better.

Snoopy's avatar

Thanks shilolo. I was indeed taking claritin for the non-sedating effect. (I have to function, after all!) My leg was a mess by last night. It is less swollen this morning, but I suspect that is because I just got up….

Thanks for the explanation. Extremely informative.

drhat77's avatar

“i hope you feel better” hmph! more informed AND has a human touch! no wonder shilolo’s got more lurve

scamp's avatar

How is it today Snoopy?

Snoopy's avatar

72 hours later after sting. No redness, swelling or pain remains. Oddly enough, there is a large 7 inch diameter bruise. It looks like I was hit w/ a baseball bat.

Thanks to all for the help and concern :)

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