Recreational drug use are caused by an excessive response of the body to allergens, such as the pollen released by grasses and trees. An allergic reaction causes release of histamine by the body. Other uses of antihistamines are to help with normal symptoms of insect stings even if there is no allergic reaction. Their recreational appeal exists mainly due to their anticholinergic properties, that induce anxiolysis and, in some cases such as diphenhydramine, chlorpheniramine, and orphenadrine, a characteristic euphoria at moderate doses. High dosages taken to induce recreational drug effects may lead to overdoses. Antihistamines are also consumed in combination with alcohol, particularly
William P. Dunbar theories about "hay fever" that were current in the late 1800s. Dunbar determined that it was the dried cat saliva on cat hair that caused the allergic reaction. With regard to grass pollen, Dunbar identified the albumin fraction as the active toxin, discovered changes in the blood that accompanied exposure to the pollen, and was able to grade individual's relative susceptibility to each type of pollen. Much of his work on allergies is summed up in his 1913 publication "The present state of knowledge of hay fever". William P. Dunbar William Philipps Dunbar (1863 in Minnesota – 1922) was an