Although itchy eye problems usually accompany other allergy symptoms, they sometimes occur separately through direct contact with an allergen. Allergic conjunctivitis--a red, teary, swollen eye condition--represents an allergic reaction by the immune system in general but not the eyes in particular. Although people inhale many allergenic substances, small particles may also strike the eye during exposure to indoor or outdoor air. Airborne allergens and those contained in liquids that make contact with the eye can all put allergy patients' health at risk.
Contact Dermatitis
Painful, severe cases of allergic conjunctivitis can develop when patients expose their eyes to chemical allergens. Inadvertent contact with an ingredient in a shampoo while showering or a fragrance in sunscreen while sweating can cause eye problems.
The Mayo Clinic says common contact dermatitis allergens that might make contact with the eye include compounds in cosmetics, detergents, soaps, deodorants, household cleaning fluids and some topical medications. Cement, paper, insecticide and other sources of dust may also create allergy symptoms in people with high levels of exposure.
Hay Fever
Besides runny nose and sneezing, the obvious signs of hay fever include seasonal allergic conjunctivitis eye problems. The overwhelming volume of pollen released by some trees, grasses and weeds can inundate the eyes with allergens that stick to the conjunctivas, the mucous membranes covering the white part of the eyes. Fungal spores from leaf mold production have similar sticky properties, and patients also inhale pollen and fungi particulate.
Intense itching, redness and swelling allergy symptoms can result in people who are sensitive to pollen or outdoor molds. According to the University of Maryland Medical Center, histamine levels set off an inflammatory response that generates itching and swelling of the eyelids. Histamines also encourage fluid migration into the mucous membranes, causing the eyes to overflow with tears.
Indoor Mold
Because mold spores travel on air currents, some fungi may enter a house and begin to grow if conditions are moist and warm enough. When these organisms reproduce, the spores become airborne indoors.
People who experience eye problems combined with respiratory discomfort at different times of the year may have perennial allergy symptoms from indoor mold exposure, notes the University of Maryland Medical Center. Visible signs of mold growing on windows or bathroom fixtures represent only the larger mold colonies. Tiny particles that are inhaled and make contact with the eyes cause the immune system to react.
Animal Allergens
Animal allergens--including chemicals in the dander or waste of pets, dust mites and cockroaches--can also cause allergic conjunctivitis symptoms. Patients encounter these substances that break down and enter the air in the same manner as indoor mold compounds. The Mayo Clinic says petting animals and then rubbing the eyes can exacerbate eye itching and redness.
