Sunday, August 17, 2014

The Value of Diphenhydramine (in the US, Benadryl)

This is a generic packaging of adult dosed diphenhydramine.

           Other than aspirin, there are few drugs that are as valuable to us in preparedness,  as Diphenhydramine. This drug has existed as a prescription drug since 1943.    My very first encounter with Diphenhydramine came in the 1970s.  I developed a significant sunburn rather quickly on my back one day, and over a few days it developed into large blisters. The area was not only painful, but areas of the lesions itched intensely.  It was difficult to sleep and I was in great discomfort.   This became one of my few trips in my youth to a hospital emergency room. Given the severity of the burn, the physician ordered an oral antibiotic, some silver based cream which I wasn't able to easily apply to the worst regions, and a prescription for Diphenhydramine for the itching and discomfort.  In the 1970s, Diphenhydramine was a prescription drug.  According to drug references, Diphenhydramine became an over-the counter drug in 1985, but I had thought it became OTC in the early eighties.  (This article has  a listing of drugs which have made the transition in the US to OTC)    This can a powerful and effective drug when used within dosage guidelines, and has multiple uses.   In the United States, Canada, and South Africa, this drug is marketed most often under the name Benadryl.  Generic preparations, simply called diphenhydramine, are also available and are just as effective, and may well be less expensive. Physicians and nurses are also able to give injectable preparations of this drug, which is not available to you OTC at home.  The drug does burn on injection.
                My first use of this drug was for intense itching, and for this it is quite effective.  It leaves most people slightly drowsy, and extreme caution should be used before driving or operating machinery until you know exactly what Diphenhydramine will do to your awareness and sensorium.

                 It can be extremely useful following everything from a beesting, a spider bite, a contact dermatitis, or swelling.
                Those who have severe reactions,such as anaphylaxis.   These are rapid and severe allergic reactions which manifest in wheezing and can move on to swelling so severe as to cause respiratory arrest and death.  Patients who have had severe reactions which include severe swelling, asthma or wheezing in response to a sting or allergen should see their physician in order to get an an emergency epinephrine injection device.
                Those of us who are not known for anaphylaxis reactions, can probably take diphenhydramine within dosage guidelines in order to avoid the worst symptoms from beestings, poison ivy, other contact allergens, spider bites, etc.

             .   Another common use for Diphenhydramine is as an antihistamine. Many people can bypass not only their allergic symptoms by using this drug, but bypass the bulk of the drowsiness by taking it at bedtime. For a percentage of patients, one dose daily will go a long way to limiting nasal, sinus, eye, and skin allergies, especially if they are generally transient or seasonal.

                 In hospitals sometimes, we need to give someone a sleeping pill, and especially with an elderly person, some of the newer medications may make them drowsy and a little confused the following day.  Sometimes, a 12.5 mg liquid dose, or a 25 mg. dose is enough to induce sleep for that person, without risking the use of a more dangerous drug.  This can also be true of those of us living at home who don't have an only rarely used sleeping pill.

                In an absolute disaster or emergency when a person becomes hysterical, and one has nothing else. Once the person has been evacuated from the immediate danger and is not needed to hike or escape from a dangerous area, one dose of diphenhydramine can be used to calm a person in such an emergency.

               There are cautions I need to give you, which was a large part of my writing this post.
In the 1980s, a few pediatricians were advocating very tiny doses of liquid diphenhydramine, that they calculated for you, in order to reverse "wake sleep disturbance of infancy."  A healthy newborn who has his days and nights confused can be given a teeny syringe measured dose of diphenhydramine three nights in a row at bedtime, and the majority of them will then sleep through the night, and be awake (as much as newborns generally are) during the day.  The practice worked well, but is now frowned upon as a percentage of parents did not adhere to the strict dosage guidelines provided by the pediatrician, and overdose injuries did occur.   This practice should not be done without dosage oversight by your pediatrician and a good reason for doing so.
             Secondly, a woman in Virginia, who apparently really needed her young son to sleep gave him liquid diphenhydramine which exceeded dosage guidelines, and accidentally killed him.  She is serving a prison sentence now
            Diphenhydramine is an effective drug for a multitude of emergency uses, but as anything with powerful positive effects, inattention to dose details, sloppiness, the repetition of doses without physician or pharmacist guidelines can cause complications, or death.  It should therefore be administered with extreme care and with great attention paid to dose guidelines.  I also recommend that the liquid drug be used with children, and the dose drawn up from the bottle using a (needleless) oral syringe, available from your pharmacy.    The drug is also a bit caustic and so it should be diluted a little using juice, for children.

This is an example of the liquid preparation which can be used for children or elderly adults.

           As a family interested in preparedness, you should have a suitable diphenhydramine preparation available for each age range within your family.  Young children should have diphenhydramine liquid and an oral syringe in a kit bagged together for allergic emergencies. Children aged 10-12 may use diphenhydramine chewable tablets. Each tablet is usually 12.5 mg.  Adults can use capsules or tablets which are 25 mg. per tab.  A small adult may take one tablet every four to six hours.  Larger adults may take two 25 mg. tablets every four to six hours.  If the drug piles up and the patient is excessively drowsy, then decrease the dose the next time the drug is due.  Follow guidelines carefully.

           This drug may also be used for other reasons.  It can be used in mentally ill patients.  It is sometimes used to decrease vomiting.  (Although should not be used in pregnant women without a specific order from her physician.)  It also has some benefit for motion sickness. It has been used to potentiate the effects of narcotics.  (It can lengthen the time a patient benefits from narcotic pain relief in the hospital setting, etc.)

             This drug has some sweeping potential positive benefits and strong effects against some serious problems.  However, I have always been a little surprised that it was made over-the-counter in the US.  This is a powerful but not an innocuous drug.   In Zambia for example, this is a controlled drug and one should not bring this drug into the country.   Potential side effects can include dizziness, excessive drowsiness, disruption in heart rhythm (aggravation of undiagnosed long qt syndrome, which can lead to sudden death),  tremors, seizures, difficulty in establishing a urinary stream, stomach pain, and sometimes there are people who become euphoric or hyperactive on it. If you have lost a relative to a sudden arrhythmic death (SADS) or a child to sudden infant death syndrome (SIDS) then I would use this drug, particularly in babies or children, only with extreme caution, and when clearly needed.

            I am not saying that we should not use this drug.  I am saying that it should be available in your home for emergency indications in its various dosages for age and weight, and that it can be used when extreme attention is paid to dosage guidelines.  It should be locked up or well secured in order to avoid accidental poisoning of children or adults with dementia.

For most people, particularly when dosing guidelines are strictly followed, the drug is quite safe and its use may be safer than allowing an evolving or chronic allergic reaction to continue unbridled.

            Delaware Pediatrics has provided an excellent page on weight and dosage guidelines for children.

Dosage chart including pediatric doses  

Dosage guidelines, particularly for pediatrics patients

Other great references on Diphenhydramine:


lotta joy said...

I don't know what we'd do without Benadryl. I add it to help sleep, but it's easy to become insensitive to it for that purpose. We have a neighbor who is prone to hysteria, given any physical ailment. This morning she called, hysterical, due to a wasp sting. I stuck a tablespoon in her freezer, made a paste with meat tenderizer, applied the cold spoon to the sting and gave her one of my Benadryl.

For Beau's horrendous allergies and scratching, he gets 1/2 Benadryl (ground fine with a pestle) and added to peanut butter. I also made a spray for him out of cortisone tablets and benadryl dissolved in aloe juice.

JaneofVirginia said...

Lotta Joy,

Thanks so much for the post. Those are great ideas. I can see I am preaching to the choir ! Even with the cautions I have placed in the post, it is indeed a very important drug, particularly for those who wish to be prepared. It also can remain potent for ten years when kept in a cool, dry, place, so we can stock up if it is locked up. Thanks again for your comment !

Tewshooz said...

Unfortunately this stuff makes me so wired that I just shake like I was pumped full of adrenalin. Heart starts racing and skipping. And sleep? Forget about it. Nyquil does the same thing. Wish there was something else I could take instead.

JaneofVirginia said...

Yes, one of the reasons I said in the post that "most" people can use diphenhydramine for sleep etc. is that there are people who have what we call a "paradoxical effect" for whom the drug works in terms of antihistaminic properties for for allergic swelling etc., but it also causes them to liberate adrenaline and experience some degree of hyperalertness and neurologic excitation. (Some mothers of children with clear ADHD know this, as some of these kids also have the paradoxical effect when receiving the drug.)
There are several other OTC antihistamines you could try to see of one of the ones that works differently works for you. I would start with only half a tablet. Cetirizine and Loratadine are now OTC. You could also ask your primary doctor what he would recommend for allergic events for you. Thanks for your post !

kymber said...

Jane - what a timely and relevant post for me. last wednesday, we went down for a dip to the river, it was lovely. but when we got back home, after taking off my flip-flops, i noticed 2 tiny puncture wounds right on the top of my foot. i hadn't felt a bite and as we have no venomous spiders in cape breton, i didn't think twice about it. 2 hours later getting ready for the vfd meeting, i had serious trouble climbing into the truck. and that's the last thing i remember. i don't remember the meeting and i don't remember a group of us going to our friends' house afterwards. we didn't stay long as jamie could see that i was not well. we came home and went to bed. i woke up on thursday and my foot was the size of a basketball!!! and black and blue!!! we called 2 of our neighbours who are emt trained and one of them said that perhaps i should go to the hospital for a tetanus shot. jam looked up some stuff on the internet and then found a number for a nursing hotline in nova scotia. man do we have some awesome services here! she spent over 30mins asking jam about 150 questions. based on her questions and his answers, she told me to ice the foot for only 10mins at a time and only 4 times a day. to keep the foot elevated at all times and to stay off it as much as possible. and she told me to take 1 benadryl a day. it's almost a week later, the swelling has gone down, the foot is almost back to normal except for their being a big, ugly bruise and i am feeling much better. the benadryl helped with the swelling, the inflammation, the pain as well as keeping me feeling drowsy enough to just lay down and let my body fight the toxin. she had asked questions about allergies, of which i don't have any, but she questioned jam enough for him to tell her that after i get too many blackfly bites, deerfly bites or mosquitoe bites that i start to swell up. which i have done all summer. so she said that since i had been battling bug venom all summer, that this spider bite would normally be innocuous but that if i was swelling and bruising the best thing for me to take was benadryl.

we had no idea that benadryl was good for the list of things that she told jam, nor the list of things that you provided in your post. we have a few bottles stored - for other people - we never thought that we would need it as we don't have allergies. well, that's changed now. thanks to the wonderful nurse on the hotline and you - we will be stocking up big time and making a large purchase next time we are in town.

thank you for such excellent information. lotta joy and tewshooz comments also provided information that i did not know. it's excellent when a post can provide so much information, and have much excellent information provided in the comments as well.much love to you and yours.
your friend,

JaneofVirginia said...


Although they are rare, both the brown recluse spider and the black widow spider are found in Nova Scotia, even sometimes on Cape Breton Island in Summer.
I am glad you stock Benadryl tablets. Benadryl or diphenhydramine cream might also be a good idea. You can use both if you need them.
I hope you have a quick and complete recovery !
Best wishes,

JaneofVirginia said...

I forgot to give you the Canadian link for these spiders: