That Are Effective and Safe Antihistamines Histamine H istamine is a natural substance, one of the important inflammatory mediators produced in certain cells in the body. W hen introduced into the nose, histamine causes dilatation and leakage of blood vessels.
Histamine is also a powerful stimulant of the sneeze reflex.
These effects of histamine cause sneezing, coughing, runny nose, and stopped up nose during colds. Histamine may also have a role in causing coughs, but this is less certain. The older class of antihistamines is effective for treating colds. A ntihistamines work by preventing histamine from attaching to a cellular receptor, H1. Attachment to this receptor is necessary for histamine activity to occur.