Final answer:
Epinephrine is the drug used to counteract the effects of anaphylactic shock, due to its ability to raise blood pressure and relax bronchial smooth muscle. It is vital for emergency treatment of severe allergic reactions and can be lifesaving.
Step-by-step explanation:
The drug that is used to counteract the effects of anaphylactic shock is epinephrine. Anaphylaxis is a severe and potentially life-threatening allergic reaction that can lead to a drop in blood pressure, contractions of bronchial smooth muscle, and other serious symptoms. Epinephrine is administered because it raises blood pressure and relaxes bronchial smooth muscle, making it crucial in the treatment of anaphylaxis. Patients at risk are often advised to carry epinephrine autoinjectors with them for emergency self-administration in case of an anaphylactic reaction.