Benadryl (diphenhydramine hydrochloride) is an antihistamine. Benadryl in the parenteral form is a sterile, pyrogen-free solution available in a concentration of 50 mg of diphenhydramine hydrochloride per mL.
Benadryl in the injectable form is effective in adults and pediatric patients, other than premature infants and neonates, for the following conditions when Benadryl in the oral form is impractical.
Antihistaminic For amelioration of allergic reactions to blood or plasma, in anaphylaxis as an adjunct to epinephrine and other standard measures after the acute symptoms have been controlled, and for other uncomplicated allergic conditions of the immediate type when oral therapy is impossible or contraindicated.
Motion sickness For active treatment of motion sickness.
Antiparkinsonism For use in parkinsonism, when oral therapy is impossible or contraindicated, as follows: parkinsonism in the elderly who are unable to tolerate more potent agents; mild cases of parkinsonism in other age groups, and in other cases of parkinsonism in combination with centrally acting anticholinergic agents.
Published Studies Related to Benadryl Injection (Diphenhydramine Injection)
Efficacy of intramuscular nalbuphine versus diphenhydramine for the prevention of epidural morphine-induced pruritus after cesarean delivery. [2011.03]
BACKGROUND: Pruritus is the most common side effect of epidural morphine analgesia. Diphenhydramine is a widely used agent for the treatment of urticarial pruritus. Nalbuphine is a mixed opioid agonist-antagonist and has been reported to be effective in treating opioid-induced pruritus. We compared the effectiveness of intramuscular diphenhydramine and nalbuphine for the prevention of epidural morphine-induced pruritus after cesarean section... CONCLUSION: Nalbuphine proved better than diphenhydramine for prevention of epidural morphine-induced pruritus in patients who underwent cesarean section. Prophylactic intramuscular nalbuphine (10 mg) is effective in decreasing the incidence and severity of pruritus and does not affect analgesia.
Antiemetic efficacy of metoclopramide and diphenhydramine added to patient-controlled morphine analgesia: a randomised controlled trial. [2010.12]
BACKGROUND AND OBJECTIVE: the objective of this study was to assess whether antiemetic drugs metoclopramide and diphenhydramine, administered together as opposed to alone, can have better efficacy in preventing postoperative nausea and vomiting when added to patient-controlled morphine analgesia... CONCLUSION: results of this study showed that a combination of metoclopramide with diphenhydramine in patients treated with dexamethasone at anaesthesia induction decreased postoperative nausea and vomiting compared to metoclopramide or diphenhydramine in these patients, when added to patient-controlled anaesthesia with morphine.
Effect of morphine and pregabalin compared with diphenhydramine hydrochloride and placebo on hyperalgesia and allodynia induced by intradermal capsaicin in healthy male subjects. [2008.12]
Intradermal (ID) capsaicin injection in humans induces spontaneous pain, flare, primary hyperalgesia, secondary hyperalgesia, and allodynia... This platform may provide a means to rapidly assess new analgesics and enhance dose selection and decision-making during clinical development.
Time-dependent inhibition of histamine-induced cutaneous responses by oral and intramuscular diphenhydramine and oral fexofenadine. [2008.05]
BACKGROUND: Diphenhydramine is often the treatment of choice for acute urticarial or allergic reactions despite its adverse effects of sedation and impairment. Second- and third-generation histamine1-antihistamines are generally devoid of these adverse effects but are typically not used because of a perceived slower onset of action. OBJECTIVE: To examine the time-dependent effects of oral fexofenadine and oral and intramuscular diphenhydramine to reduce histamine-induced wheal-and-flare responses... CONCLUSION: Diphenhydramine tended to work more rapidly than fexofenadine, but the differences were not statistically significant. Given the adverse effect profile of diphenhydramine, but only marginal onset of action advantage, the risk-to-benefit ratio may be more favorable for oral fexofenadine when treating an acute urticarial or allergic reaction.
A clinical trial of trimethobenzamide/diphenhydramine versus sumatriptan for acute migraines. [2006.06]
BACKGROUND: Although various classes of medication are used to treat acute migraine in the emergency department (ED), no treatment offers complete pain relief without side effects or recurrence of headache. Consequently, even though several antiemetic medications as well as SQ sumatriptan have demonstrated efficacy and tolerability for the ED treatment of migraine, there remains a need for more effective parenteral therapies. Open-label studies suggest that the combination of trimethobenzamide and diphenhydramine (TMB/DPH) may provide effective relief in a high proportion of migraineurs. OBJECTIVE: To test the hypothesis that ED patients with acute migraine, given intramuscular TMB/DPH, would have a larger reduction in their pain scores than patients given SQ sumatriptan... CONCLUSIONS: SQ sumatriptan is probably superior to TMB/DPH for treating the pain of acute migraine at 2 hours. However, TMB/DPH was well-tolerated, efficacious, and relieved pain comparably to sumatriptan at 24 hours. TMB/DPH might have a role in select populations in which sumatriptan is contraindicated or likely to be ineffective.
Clinical Trials Related to Benadryl Injection (Diphenhydramine Injection)
To Determine if Diphenhydramine Works for Nasal Congestion at Two Different Doses [Completed]
The study was to determine if the drug worked to relieve nasal congestion experienced by
people with seasonal allergies.
A Dose Ranging Effect of Preoperative Diphenhydramine on Postoperative Quality of Recovery After Ambulatory Surgery [Recruiting]
Pain after ambulatory surgery remains an unsolved problem in The United States and Europe.
It is associated with delayed hospital discharge and it can result to an increased opioid
consumption with adverse side effects. The concept of multimodal analgesic technique was
introduced more than 15 years ago and several techniques have been studied over the years
including non steroidal antiinflammatory drugs (NSAIDs), acetaminophen, gabapentoids,
ketamine, local and regional anesthetic techniques. Histamine can have effects on polymodal
nociceptors and C-fibers, producing pain which is further increased by neurogenically
mediated release of substance P from afferent pain fibers. Several non-selective or H1
- selective histamine receptors antagonists have been demonstrated in animal models and
clinical pain. Chia et al demonstrated that preoperative promethazine had opioid sparing
properties without adverse sedative effects in patients undergoing abdominal hysterectomy.
Diphenhydramine is an anti-histamine drug who has been found to be effective in reducing
postoperative nausea and vomiting after ambulatory surgery but its effects on postoperative
pain and other important outcomes after ambulatory surgery such as time to meet discharge
criteria have not being studied.
The MQOR 40 is a validated instrument that was specifically design to evaluate patient
recovery after anesthesia and surgery. This instrument can be particularly valid to examine
interventions which affect different spheres of patient recovery as is the case of
diphenhydramine. The objective of this study is to determine a dose response effect of
preoperative diphenhydramine on postoperative quality of recovery after ambulatory surgery.
The use of preoperative diphenhydramine can improve patient's quality of recovery, decrease
postoperative pain, opioid consumption and opioid related side effects after ambulatory
The research question: Does a preoperative dose of diphenhydramine improve postoperative
quality of recovery after ambulatory surgery? The hypothesis of this study is that
preoperative diphenhydramine will improve postoperative pain, Postoperative nausea and
vomiting (PONV), sleep which will translate in a better overall quality of recovery.
Pharmacogenetic Factors and Side Effects of Metoclopramide and Diphenhydramine [Recruiting]
Lorazepam, Diphenhydramine Hydrochloride, and Haloperidol Gel in Patients With Nausea [Recruiting]
This randomized clinical trial studies lorazepam, diphenhydramine hydrochloride, and
haloperidol gel in patients with nausea. Lorazepam, diphenhydramine hydrochloride, and
haloperidol gel, when absorbed into the skin, may be an effective treatment for nausea and
Adjunct Sedatives in Procedures Involving Endoscopic Ultrasound (EUS) and Endoscopic Retrograde Cholangiopancreatography (ERCP) [Recruiting]
The purpose of this study is to compare meperidine/midazolam with diphenhydramine,
meperidine/midazolam with promethazine, and meperidine/midazolam with placebo as sedation
methods. The investigators are interested to see whether adjunct sedatives (diphenhydramine
and promethazine) will improve sedation.