Conjunctivitis (Pink Eye)

What Is Conjunctivitis (Pink Eye)?

Conjunctivitis is inflammation of the conjunctiva, the thin, filmy membrane that covers the white of your eye. The conjunctiva, which produces mucus to coat and lubricate the surface of the eye, contains fine blood vessels that can be seen on close inspection. When the conjunctiva becomes irritated or inflamed, the blood vessels, which supply it, enlarge and become more prominent, causing the eye to turn red.


  • Pinkness or redness in the eye
  • Red, inflamed inner eyelids
  • Blurred vision
  • Sandy or scratchy feeling in the eye
  • Pus, mucous, or watery discharge from the eye

The symptoms described above may not necessarily mean that you have conjunctivitis. However, if you experience one or more of these symptoms, contact your ophthalmologist for a complete exam.


There are many sources of eye irritation that can cause conjunctivitis.

  • Bacterial Conjunctivitis
    Bacterial infections can cause a red eye, which is associated with pus or discharge from the eye, or they can cause a red eye which is associated with crusting of the eyelashes with little or no discharge.
  • Viral Conjunctivitis
    Viruses can cause conjunctivitis, such as the familiar red eyes, sore throat, and runny nose of a common cold. Viral conjunctivitis usually produces a watery mucous discharge and lasts from 1 to 2 weeks. Infectious conjunctivitis, commonly known as "pink eye," can be quite contagious. Cloth handkerchiefs and towels should not be shared during this time. Hand washing also will help prevent the spread of this infection.
  • Allergies
    Allergies can cause conjunctivitis, which produces a stringy, white discharge. Allergies can make the eyes itchy or produce a chronic red eye and environmental irritants, such as smoke or fumes, may cause conjunctivitis. Any type of conjunctivitis is aggravated by dryness of the eyes.

Risk Factors

The risk factors for conjunctivitis depend on the type of conjunctivitis.  Bacterial conjunctivitis results from exposure to a bacterial organism to which the eye is vulnerable.  Some of the more worrisome types of bacterial conjunctivitis can be caused by organisms that also cause sexually transmitted diseases; a sudden onset of the above symptoms in the context of a new sexual partner needs to be evaluated. 

Viral conjunctivitis is extremely contagious.  Often the person with viral conjunctivitis has had an upper respiratory infection preceding the onset of the red eye or has been around someone with an upper respiratory infection.  People who work in health care settings or with children have a high risk of exposure to the viruses that can cause viral conjunctivitis.

Allergic conjunctivitis is caused by the environmental factors that trigger an allergic reaction in the eye and these triggers are different for each person.

Tests and Diagnosis

The different types of conjunctivitis often can be distinguished by an eye examination, including your medical history. If your ophthalmologist suspects bacterial conjunctivitis, s/he will culture your eyelids, conjunctiva, and discharge to make a diagnosis and choose the best treatment. Viral and allergic conjunctivitis often do not require special testing for diagnosis.

Treatment and Drugs

If you think you might have conjunctivitis, you should

  • Keep your hands away from your eyes
  • Thoroughly wash your hands before and after applying eye medications
  • Do not share towels, washcloths, cosmetics, or eyedrops with others
  • Seek treatment promptly
  • Small children, who may forget these precautions, should be kept away from school, camp, and the swimming pool until the condition is cured

Treatment for Bacterial or Viral Conjuntivitis

Infectious conjunctivitis, caused by bacteria, usually is treated with antibiotic eye drops and/or ointment. Other infectious forms, caused by viruses, can't be treated with antibiotics. They must be fought off by your body's immune system. But some antibiotics may be prescribed to prevent secondary bacterial infections from developing.  Artificial tears and warm compresses may help keep the eye comfortable while viral conjunctivitis runs its course.

Treatment for Allergic Forms of Conjuntivitis

When treating allergic and chemical forms of conjunctivitis, the cause of the allergy or irritation must first be removed. For instance, avoid contact with any animal if it causes an allergic reaction. Wear swimming goggles if chlorinated water irritates your eyes. In cases where these measures won't work, prescription and over-the-counter eye drops are available to help relieve the discomfort.

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Reviewed by Jill E. Bixler, M.D.