Drugs that combat the histamine circulated during an allergic attack by preventing the action for the histamine in the tissue. Antihistamines try not to stop the formation of histamine nor do they stop the conflict between your IgE and antigen. Consequently, antihistamines don't stop the allergic effect but protect areas from a few of its effects. Antihistamines frequently cause mouth dryness and sleepiness. New "non sedating" antihistamines are thought to be somewhat less effective. Antihistamine complications that very periodically occur include urine retention in males and fast heartrate.