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
Allergic conjunctivitis Horner-Trantas dots are specific features of vernal type. Giant papillary conjunctivitis is not a true ocular allergic reaction and is caused by repeated mechanical irritation of the conjunctiva. Repeated contact with the conjunctival surface caused by the use of contact lenses is associated with GPC. PKC results from a delayed hypersensitivity/inflammatory reaction to antigens expressed by various pathogens. Common agents include Staph. aureus, Mycobacterium tuberculosis, Chlamydia and Candida. A detailed history allows physicians to determine whether the presenting symptoms are due to an allergen or another source. Diagnostic tests such as conjunctival scrapings to look for eosinophils are helpful in