Conjunctivitis is swelling and irritation in the eye. It affects the tissue that covers the eye and lines the inner surface of the eyelid. This tissue is called the conjunctiva.

Eye with Conjunctivitis
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There are many causes of conjunctivitis including:

  • Viral infection
  • Bacterial infection
  • Allergic reaction, usually related to seasonal allergies
  • Chemical irritation caused by:
    • Air pollutants
    • Soap
    • Smoke
    • Chlorine
    • Make-up
    • Other chemicals

Both viral and bacterial conjunctivitis are highly contagious.