Benadryl as a Local Anesthetic in Survival?

Benadryl as a Local Anesthetic in Survival?

diphenhydramine (Benadryl)

A major obstacle in the ability of the survival medic to deal with the issue of wound closure is the lack of an easily available (and stockpile-able) form of anesthesia. With the most popular local anesthetic, lidocaine, a prescription item, it may be difficult to obtain enough to adequately fill the need in long-term disaster scenarios.

We often mention in our podcast that we learn as much (really, more) from our readers and listeners than they do from us. Now, we are informed that diphenhydramine (Benadryl) may serve, in its injectable form, as a reasonable alternative for local anesthesia.

You won’t find this information at drugs.com or other general medical information sites. Ordinarily, you’ll read that diphyenhydramine (DPH) is an antihistamine that reduces the effects of natural chemical histamine in the body. Diphenhydramine is used to treat sneezing, runny nose, itching, watery eyes, rashes, and some cold or allergy symptoms. It also serves as a remedy for motion sickness, a hypnotic (sleep-inducer), and even to treat certain aspects of Parkinson’s disease.

Benadryl comes in oral form as well as an injectable solution. Although controversial, the injectable has been used as a local anesthetic since 1956. It has been used in minor skin, dental, and podiatric procedures, especially in those allergic to lidocaine. This comment from a pharmacist’s emergency medicine blog:

“In one validation study for its use as a dermal anesthetic, a prospective, randomized, double-blind, placebo-controlled study was conducted to assess both the degree of anesthesia (in square millimeters) and pain associated with injection in 24 subjects who received 0.5-mL injections of 1% DPH, 2% DPH, 1% lidocaine, and 0.9% sodium chloride placebo. Subjects who received 1% DPH achieved equivalent level of anesthesia relative to 1% lidocaine (p = 0.889); in addition, 1% DPH more effective in this outcome compared to 2% DPH. However, subjects did experience greater perception of pain at injection with both concentrations of DPH relative to 1% lidocaine (more pain perceived with 2% DPH), with some subjects experiencing persistent discomfort in the injected area for up to three days following injection. In another study evaluating other concentrations of  DPH for local anesthesia, although a concentration of 0.5% DPH was deemed similar in perception of pain by patients upon injection compared to 1% lidocaine and a viable alternative to 1% lidocaine in maintaining local anesthesia, it was less effective than lidocaine when used for repairing minor skin lacerations in the face. In other head-to-head comparisons of 1% DPH and 1% lidocaine, similar levels and depths of local anesthesia were achieved.”

Like all drugs, there are possible adverse effects. The use of DPH as a local anesthetic may be associated with local necrosis (tissue death) at the site of injection. This usually occurs from the use of excessively high concentrations of the medication. As such, you will see it contraindicated as a local anesthetic on most medical websites. At normal dosages, sedation may be noticed, as well as local soreness. Be aware that it might burn as it is administered and that its safety is not confirmed in distal areas like fingers, toes, ears, and nose.

Injecting local anesthetic

The recipe is as follows, again from our pharmacist’s blog:

“Steps:

Draw up entire contents of vial containing 50 mg/mL diphenhydramine into the syringe. This should measure to a volume of 1 mL.

Dilute the contents of the syringe with 4 mL of 0.9% sodium chloride to yield a final volume of 5 mL.

Clearly label the contents of the syringe with the medication label as “Diphenhydramine 1% (10 mg/mL).”

Usually, the appropriate effect can be achieved with 2 ml or so of the injectable Benadryl. Use as little as possible to achieve the desired effect.

From the standpoint of availability, I was able to order the product as a private citizen (as opposed to a physician) from at least one veterinary website. That doesn’t mean that it is widely available, however.

The survival medic’s job is a difficult one. Searching for additional tools in the medical woodshed isn’t easy, but necessary if the medic is to be effective in an austere off-grid setting. Of course, in normal times, seek modern and standard medical care from qualified professionals.

 

Some additional support from conventional medical journals for the anesthetic effect of diphenhydramine:

Green SM, Rothrock SG, Gorchynski J: Validation of diphenhydramine as a dermal local anesthetic. Ann Emerg Med 1994; 23:1284-1289.

Ernst AA, Marvez-Valls E, Mall G, et al. 1% Lidocaine versus 0.5% diphenhydramine for local anesthesia in minor laceration repair. Ann Emerg Med 1994; 23:1328-1332.

Dire DJ, Hogan DE. Double-blinded comparison of diphenhydramine versus lidocaine as a local anesthetic. Ann Emerg Med 1993; 22:1419-22.

Ernst AA, Anand P, Nick T, et al. Lidocaine versus diphenhydramine for anesthesia in the repair of minor lacerations. J Trauma 1993; 34:354-7.

 

Joe Alton, MD

Joe Alton MD

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