Final answer:
Epinephrine is the drug used to treat anaphylactic reactions due to its rapid action in improving breathing, raising blood pressure, and reducing swelling, making it essential for immediate treatment. Antihistamines are used for mild allergies but are not adequate for anaphylactic shock.
Step-by-step explanation:
An anaphylactic reaction is a severe and potentially life-threatening response to an allergen characterized by a sudden drop in blood pressure, airway constriction, and other systemic symptoms. To counteract this, epinephrine is administered because it has the ability to quickly improve breathing, stimulate the heart, raise dropping blood pressure, and reduce swelling. While antihistamines are useful for treating mild allergy symptoms by blocking the effects of histamines, they are not sufficient in the case of anaphylaxis. Instead, epinephrine is the first-line treatment, often provided through an auto-injector, which allows for immediate self-administration in urgent situations.
Patients with known severe allergies are commonly advised to carry an epinephrine autoinjector with them at all times. This ensures that they can respond quickly in the event of anaphylactic shock, thereby mitigating the severe effects and buying time to seek emergency medical care. Antihistamines and corticosteroids may be prescribed after an anaphylactic event as part of follow-up care to prevent late-phase reactions, but they do not replace the immediate need for epinephrine.