B52
The “B52” is well named because, just like the B52 bomber, it will get the job done but will likely cause a great deal of collateral damage - Big Book of Emergency Department Psychiatry

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HWN Suggests
To B or Not to B: B52 v 52 for Acute Agitation
Diphenhydramine (B) has historically been utilized in combination with haloperidol 5mg and lorazepam 2mg in the treatment of acute agitation. The most common rationale for adding diphenhydramine is prevention of EPS, however literature to support this is lacking. A recently published paper examined diphenhydramine/haloperidol/lorazepam combination (B52) vs haloperidol/lorazepam combination therapy to compare the need for additional agitation treatments as a surrogate for clinical efficacy.
Articles of Interest
B52 medicine
The problem is that you have likely now created a patient that will be so sedated as to be unable to participate in directing their care or giving the medical team important information about their history. The “B52” is well named because, just like the B52 bomber, it will get the job done but will likely cause a great deal of collateral damage.
Combining B52 & 52 Antipsychotic & Sedative To Treat Acute Agitation
Repeat agitation medication was required seldom in both the B52 and 52 combinations; however, the B52 combination resulted in higher oxygen desaturation, hypotension, physical restraint use, and a longer length of stay.
Efficacy of Combination Haloperidol, Lorazepam, and Diphenhydramine vs. Combination Haloperidol and Lorazepam in the Treatment of Acute Agitation: A Multicenter Retrospective Cohort Study
Both the B52 and 52 combinations infrequently required repeat agitation medication; however, the B52 combination resulted in more oxygen desaturation, hypotension, physical restraint use, and longer length of stay.
Intramuscular B52
This article stems from the widespread use of this cocktail. On the basis of many psychiatrists’ personal anecdotes, it seems to work well. But, does its teaching harm an approach to psychiatry that is evidence based?
Should Diphenhydramine be included in an Acute Agitation Regimen?
Diphenhydramine may not be necessary when using haloperidol + lorazepam to treat agitation in the ED. ED length of stay is increased with the addition of diphenhydramine to haloperidol + lorazepam.

