Conjunctivitis, also known as pink eye, is one of the most common and treatable eye conditions in children and adults. It is an inflammation of the thin, clear lining inside the eyelid and on the white of the eye. This inflammation gives the eye a pink or reddish color.

What causes conjunctivitis?

Conjunctivitis is caused by viruses, bacteria, allergens [like pet dander or dust mites], and irritants [like smog or swimming pool chlorine] that infect or irritate the eye and eyelid lining.

What are the symptoms of conjunctivitis?

Depending on the cause, the signs and symptoms for conjunctivitis may vary, but they usually include:

* Redness or swelling of the white of the eye or inside the eyelid

* Increased amount of tears

* White, yellow or green eye discharge

* Itchy eyes

* Burning eyes

* Increased sensitivity to light

* Gritty feeling in the eye

* Crusting of eyelids or lashes

How is conjunctivitis treated?

The treatment for conjunctivitis depends on the cause. Conjunctivitis is usually mild and will often get better on its own, even without treatment. However, there are times when it is important to see a health-care provider and get an antibiotic or other medical treatment.

How do I stop conjunctivitis from spreading?

Conjunctivitis that is caused by allergens or irritants is not contagious, but a secondary infection by viruses or bacteria is possible. Viral and bacterial conjunctivitis are very contagious and spread easily and quickly from person to person. By following simple self-care steps, like washing your hands and not touching your eyes, you can reduce the risk of getting or spreading conjunctivitis.

When should I call a health-care provider?

Although most cases of conjunctivitis are mild and get better without treatment, some forms are more severe. Severe cases need to be looked at by a health-care provider and may require specific treatment and close follow-up. If you have conjunctivitis, you should see your health-care provider if you have:

* Moderate to severe pain in your eye(s)

* Blurred vision or increased sensitivity to light

* Intense redness in the eye(s)

* A weakened immune system, for example, from HIV or cancer treatment

* Bacterial conjunctivitis that does not improve after 24 hours of antibiotic use

* Symptoms that get worse or don't improve

* Pre-existing eye conditions that may put you at risk for complications or severe infection

Conjunctivitis in newborns

Conjunctivitis in newborns can be caused by an infection, irritation or a blocked tear duct. A newborn baby who has symptoms that look like conjunctivitis should see a health-care provider. Neonatal conjunctivitis caused by sexually transmitted infections, like gonorrhea or chlamydia, can be very serious. If you are pregnant and think you may have a sexually transmitted infection, visit your health-care provider for testing and treatment.

If you don't know whether you have a sexually transmitted infection but have recently given birth and your newborn shows signs of conjunctivitis, visit your child's health care provider right away.

Most hospitals are required by state law to put drops or ointment in a newborn's eyes to prevent conjunctivitis.