Ontario Paramedic Practice Exam

Diphenhydramine is an antihistamine commonly used to treat allergic reactions by blocking the effects of histamine, which is released during an allergic response. It is important to administer diphenhydramine under specific conditions to ensure patient safety and to maximize its efficacy.

The correct condition for administering diphenhydramine, particularly in cases of allergic reactions, is when the patient weighs equal to or over 25kg. This is primarily due to the dosing guidelines which are based on weight. For patients under this weight, especially children, the risk of adverse effects or improper dosing can increase. Therefore, ensuring that a patient is at least 25kg allows for a more standardized and safer dosing regimen.

In mild allergic reactions, while diphenhydramine can be used, it is essential to assess the severity of the reaction and the appropriate intervention. In situations where a patient does not respond to epinephrine (which is the first-line treatment for severe allergic reactions like anaphylaxis), diphenhydramine can be considered as a supplemental treatment. However, relying solely on it in critical situations can be inappropriate.

Overall, administering diphenhydramine based on weight is crucial to avoid underdosing or overdosing, ensuring the