- A substance that is foreign to the body and can cause an allergic reaction in certain people. For examples, pollen, dander, mold.
* * *Term for an antigen that induces an allergic or hypersensitive response. [allergy + G. -gen, producing]
* * *al·ler·gen 'al-ər-jən n a substance that induces allergy <inhaled \allergens> <a suspected food \allergen>
* * *n.any antigen that causes allergy in a hypersensitive person. Allergens are diverse and affect different tissues and organs. Pollens, fur, feathers, mould, and dust may cause hay fever; house-dust mites (see Dermatophagoides) have been implicated in some forms of asthma; drugs, dyes, cosmetics, and a host of other chemicals can cause rashes and dermatitis; some food allergies may cause diarrhoea or constipation or simulate acute bacterial food poisoning. When a patient's allergen has been identified (see patch test), it may be possible to attempt desensitization to alleviate or prevent allergic attacks.• allergenic adj.
* * *al·ler·gen (alґər-jən) [allergy + -gen] an antigenic substance capable of producing immediate-type hypersensitivity (allergy).
Medical dictionary. 2011.