Which medication is often used as a rescue treatment for severe allergic reactions?

Epinephrine is the medication commonly used as a rescue treatment for severe allergic reactions, such as anaphylaxis. Anaphylaxis is a potentially life-threatening condition that occurs when the body has a severe allergic response to a substance. Epinephrine works rapidly to counteract the symptoms of anaphylaxis by constricting blood vessels, which helps to increase blood pressure, and relaxing the muscles of the airways, making it easier to breathe. Additionally, it reduces swelling and hives by its anti-inflammatory effects. This immediate action is critical in emergencies, making epinephrine the first-line treatment in acute allergic reactions.

In contrast, the other medications mentioned, such as cetirizine, loratadine, and fexofenadine, are antihistamines that provide relief from milder allergic symptoms like itching, runny nose, and sneezing. However, they do not have the same rapid, life-saving effects that epinephrine has and are not suitable for treating severe allergic reactions. Understanding the appropriate use of these medications is key in managing allergic responses effectively.