• Conjunctivitis: Causes of Pink Eye

    Written by: Kierstan Boyd
    Reviewed by: Elena M Jimenez MD
    Oct. 13, 2015

    The most common causes of pink eye (conjunctivitis) are:

    • Infections (viral or bacterial);
    • Allergies; and
    • Irritation from something in the environment.

    Viral infection is a common cause of conjunctivitis. This same virus that produces red and watery eyes also causes the sore throat and runny nose of the common cold. Symptoms of viral conjunctivitis can last from a few days to two weeks and then will disappear on their own. Discomfort, however, can be minimized with cool compresses applied to the eyes. Antibiotic eyedrops do not cure viral conjunctivitis.

    Bacterial infections, such as Staphylococcus or Streptococcus, cause a red eye with a lot of pus. Often the eyelids are glued shut on awakening. Infrequently, bacterial infections will produce little or no discharge except for some mild crusting of the eyelashes in the morning. Antibiotic eyedrops are often prescribed because they speed the eye's healing and reduce contagion.

    Allergic conjunctivitis is not infectious or contagious. It occurs when the body is exposed to something that causes an allergic reaction, such as pollen or other environmental allergen, or pet dander. The primary symptom is itching. Other common symptoms include redness of the conjunctiva, burning, tearing, and puffy eyelids. Occasionally the conjunctiva becomes swollen. Treatment often includes applying cool compresses to the eyes and using anti-allergy eyedrops and artificial tears. Many patients find that drops that have been cooled in the refrigerator are especially comforting. Oral anti-allergy medications do not significantly improve the symptoms of ocular allergies.

    Environmental irritants, such as smoke or fumes, may also cause conjunctivitis. The symptoms are burning and irritation, with no discharge or watery discharge.

    How do you get infectious pink eye?

    Conjunctivitis, whether bacterial or viral, can be quite contagious. Some of the most common ways to get the contagious form of pink eye include:

    • Forgetting to wash your hands often and touching your eyes;
    • Reusing tissues and towels when wiping your face and eyes;
    • Not cleaning your contact lenses properly and using poorly fitting contact lenses or decorative contacts; or
    • Using infected eye makeup.

    If you have pink eye, avoid wearing eye makeup and do not share makeup with anyone. Once your infection clears, replace your makeup to avoid possible reinfection. Bacteria can live in makeup and cause pink eye; even worse, it can cause corneal infections, which can be sight-threatening.

    Children are usually most susceptible to getting pink eye from bacteria or viruses because they are in close contact with so many others in school or day care centers.

    Conjunctivitis is typically a short-lived condition that may require eyedrops. However, if symptoms continue for an extended period of time after treatment, you should have your eyes examined by your ophthalmologist (Eye M.D.), as these symptoms may indicate a more serious eye problem. Several eye diseases can cause red eye, some of which can lead to blindness unless diagnosed and treated.