What is pink eye (conjunctivitis)?

Conjunctivitis, often called "pink eye," is an inflammation (redness) of the conjunctiva, the clear tissue that lines the inside surface of your eyelid and outer coating of your eye. This tissue helps keep your eyelid and eyeball moist.

Pink eye can occur in one or both eyes. Pink eye that occurs in both eyes tends to be caused by a virus.

How common is pink eye (conjunctivitis)?

Pink eye is one of the most common eye infections in children and adults. Between three and six million cases of pink eye occur in the U.S. each year.

What causes pink eye (conjunctivitis)?

Technically, the pink or reddish color of pink eye happens when the blood vessels in the membrane covering your eye (the conjunctiva) becomes inflamed, making them more visible. This inflammation is caused by:

  • Viruses. Viruses are the most common cause of pink eye. Coronaviruses, such as the common cold or COVID-19, are among the viruses that can cause pink eye.
  • Bacteria. Common types of bacteria that causes bacterial conjunctivitis includes Staphylococcus aureus, Haemophilus influenzae, Streptococcus pneumonia and Pseudomonas aeruginosa.
  • Allergens including molds, pollen or other substances that cause allergies.
  • Irritating substances, such as shampoos, cosmetics, contact lenses, dirt, smoke and especially pool chlorine.
  • Sexually transmitted infections, which could be caused by a virus (herpes simplex) or bacteria (gonorrhea or chlamydia).
  • Foreign object in the eye.
  • Blocked or incompletely opened tear duct in babies.

Is pink eye (conjunctivitis) contagious? How long am I contagious?

Pink eye that is caused by bacteria or viruses are very easily spread from person to person (contagious). If you get pink eye from bacteria, you can spread pink eye while you have symptoms or until about 24 to 48 hours after starting antibiotic treatment. If you get pink eye from a virus, you can spread it for as long as you have symptoms and even before you develop symptoms. This could be for several days. Pink eye caused by an allergy is not contagious.

How is pink eye (conjunctivitis) spread?

Pink eye is spread:

  • From transfer of the bacteria or virus during close contact (touching, shaking hands). The germs transfer from the hand of the infected person to your hand then to your eye when you touch your eye.
  • By touching surfaces contaminated with the bacteria or virus (from infected individuals who have transferred the germs from their hands to objects), then touching your eyes before washing your hands.
  • By using unclean old eye makeup or sharing makeup that has become contaminated with bacteria or viruses.

What are the symptoms of pink eye (conjunctivitis)?

Symptoms of pink eye include:

  • Redness in the white of the eye or inner eyelid.
  • Increased tearing.
  • Thick yellow discharge that crusts over the eyelashes, especially after sleep (in conjunctivitis caused by bacteria).
  • Other discharge from your eye (green or white).
  • Gritty feeling in one or both eyes.
  • Itchy eyes (especially in pink eye caused by allergies).
  • Burning eyes (especially in pink eye caused by chemicals and irritants).
  • Blurred vision.
  • Increased sensitivity to light.
  • Swollen eyelids.

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