Definition of allergen in English:



  • A substance that causes an allergic reaction.

    • ‘The rash usually clears if the allergen is no longer in contact with the skin, but recurs with any slight contact with it again.’
    • ‘Once a person is sensitized to an allergen or chemical, he or she may develop asthma.’
    • ‘Your doctor may take tests to see what allergens are causing the hay fever symptoms.’
    • ‘Your allergic reaction happens when your body's immune system mistakes the allergen for a harmful invader.’
    • ‘Gradually your body learns to accept the allergen as the harmless substance it is.’
    • ‘The goal is to desensitize you to specific allergens and decrease your need for medications.’
    • ‘Future exposure to the same allergens will cause the reaction to happen again.’
    • ‘Wherever possible, the most effective way of treating allergies is to avoid all contact with the allergen causing the reaction.’
    • ‘Eliminate any known allergens such as certain foods, dust, or pet dander from your household.’
    • ‘It is well known that vacuum cleaner bags capture large particles but can emit allergens that are too small to be collected in the bag.’
    • ‘Whether your eczema is due to an irritant, such as detergent, or due to an allergen, such as nickel, care and treatment of your skin is the same.’
    • ‘If you take away the allergens that were driving it initially, the inflammation is likely to continue.’
    • ‘The next time you're exposed to the allergen, your immune system launches an allergic reaction.’
    • ‘Allergies are caused by the body's immune system reacting to allergens as if they were harmful.’
    • ‘Avoid things that could make symptoms worse, such as air pollution and allergens.’
    • ‘First, allergic reactions are caused by allergens, the three most common ones being dust and mites, pollen and nuts.’
    • ‘During allergy seasons, the local news broadcasts usually tell you what allergens are in the air.’
    • ‘If allergens in the air are an asthma trigger, pollutants can make the lungs even more sensitive to them.’
    • ‘In such an enclosed environment, allergens from one food can spread to another.’
    • ‘Substances that are normally harmless could act as allergens and trigger a reaction in certain people.’


Early 20th century: blend of allergy and -gen.