What is the route of administration for diphenhydramine in this material?

• A. IV
• B. PO (oral)
• C. IM
• D. SC

Answer: (B)

The key idea is that this material presents diphenhydramine for use by mouth, meaning the oral route is the intended method of administration. When a patient can swallow and airway protection isn’t at risk, giving diphenhydramine PO is practical in prehospital care because it’s easy to administer, reduces the need for injections, and has a reliable absorption pattern in this setting. The onset is slower than injections—usually 20 to 60 minutes with peak effect over a couple of hours—yet it provides effective allergy symptom relief with fewer immediate risks.

Intravenous administration would bring a faster onset but carries greater risks and logistical requirements (IV access, monitoring, potential hypotension, and infusion-related complications). Intramuscular administration delivers quicker onset than oral but involves injections, potential tissue irritation, and patient discomfort. Subcutaneous delivery isn’t typically used for diphenhydramine due to less predictable absorption. Therefore, the material aligns with the oral route as the best fit for routine, nonemergent allergic reactions when the patient can take medication orally.