Encyclopedia / C / Conjunctivitis


What Is Conjunctivitis?

Conjunctivitis is an inflammation of the mucous membranes (conjunctiva) that line the inner surface of the eyelids and the whites of the eyes. It may be triggered by an infection, an allergic reaction, exposure to a chemical or irritant, or by inflammation in or around the eyes. Conjunctivitis is commonly called pinkeye because the blood vessels in the whites of the eyes dilate and redden, giving the eye a pinkish hue to the observer. Conjunctivitis can be highly contagious when caused by an infection. Although usually not serious, conjunctivitis should be treated promptly to prevent possible complications and transmission to others. With treatment, conjunctivitis generally disappears within one to three weeks.

Who Gets Conjunctivitis?

Viral conjunctivitis, the most common form of pink-eye, can affect both children and adults, and is usually caused by the same virus that causes the common cold, which is why cases of viral conjunctivitis are often associated with a cold or upper respiratory tract infection, or exposure to someone with a history of this type of infection. Bacterial conjunctivitis, while more common in children, is much less common than viral conjunctivitis. Newborns (infants from birth to 3 months of age) are highly susceptible to bacterial conjunctivitis and can develop more serious complications if the condition goes untreated. As a preventive measure, all newborns are treated with antibiotic eye drops or ointment immediately after birth.


  • Redness of the white of the eye.
  • Itching and a gritty sensation in the eye.
  • Oozing discharge from the eyes.
  • Excessive tearing.
  • Dried crusts that form during sleep may bind the eyelids together.
  • Swollen eyelids.
  • Aversion to bright lights (photophobia).
  • Allergic conjunctivitis is typically associated with intense itching of the eyes and/or eyelids, as well as the presence of whitish, rope-like discharge in the eyes.

Causes/Risk Factors

  • Viral infections and allergies are the most common causes of conjunctivitis. If viral conjunctivitis occurs in one eye, it can easily be spread to the other eye by touching the eyes. It can also be easily passed from one person to another by direct contact or by sharing towels or washcloths that have been used to wipe infected eyes.
  • Allergies (to such things as pollen, cosmetics, and contact lens cleaning solution) are a common cause of conjunctivitis. Allergic conjunctivitis, unlike viral or bacterial conjunctivitis, is not contagious.
  • Air pollution or chemical irritants may lead to conjunctivitis.
  • Cervical infections (chlamydia, genital herpes, or gonorrhea) in a pregnant woman may result in potentially blinding conjunctivitis in the baby.
  • A partially blocked tear duct is a possible cause.

What if You Do Nothing?

Viral conjunctivitis is usually not a serious eye ailment and typically clears up in one to two weeks, though symptoms can be bothersome for adults and children alike. Bacterial conjunctivitis is more serious than the viral form and usually requires diagnosis and treatment by a doctor. Allergic conjunctivitis can persist until the source of the reaction has been identified and dealt with. Some childhood diseases—measles, German measles (rubella), and chicken pox—can also cause conjunctivitis.


  • The diagnosis can generally be made by the typical findings on physical examination.
  • Swab samples may be taken and cultured to identify the type of bacterial infection involved.


  • First, consult a doctor or ophthalmologist to confirm the diagnosis. It is important to determine whether infectious conjunctivitis is bacterial or viral in origin. Bacterial conjunctivitis is the more serious of the two and requires treatment; viral conjunctivitis typically resolves on its own, without complication.
  • Your doctor may prescribe antibiotic or steroid eyedrops or ointments. Use as directed and be careful not to allow the tip of the eyedrop bottle to touch the eyes.
  • For infectious conjunctivitis, soak a clean cloth in warm water, wring it dry, and apply it to the eye. Avoid touching or rubbing the infected eye with your bare finger.
  • For allergic conjunctivitis, apply cool compresses to the eye. Allergy eye drops and/or oral antihistamines may be recommended. .


  • Try to avoid touching the eyes if not necessary. Most of us touch our eyes without thinking, so not touching them requires an effort. If, however, touching the eyes is necessary, such as when handling contact lenses, be sure to wash your hands both before and after.
  • Wash your hands often with soap and warm water.
  • Change towels and pillowcases often.
  • Do not share towels.
  • Do not share eye makeup; replace cosmetics every four to six months.
  • Avoid substances that trigger eye irritation.

When To Call Your Doctor

  • Call a doctor if conjunctivitis symptoms do not improve after three or four days of treatment, especially if redness and any discharge worsen, or if fever, increased pain, or changes in vision develop. In the case of bacterial conjunctivitis, prompt treatment will avert complications.

Reviewed by Daniel E. Bustos, M.D., M.S., Private Practice specializing in Comprehensive Ophthalmology in Nashville, TN. Review provided by VeriMed Healthcare Network.