Question

what do medications have to contain to help with an allergic reaction?
morphine
antihistamines
histamines

Explanation:

Allergic reactions are caused by the release of histamine in the body. Antihistamines work by blocking the action of histamine, thus relieving allergic - reaction symptoms. Morphine is a pain - reliever and not used for allergic reactions. Histamines themselves cause allergic reactions, not help with them.

Answer:

B. Antihistamines