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Conjunctivitis, also known as "pink eye," is characterized as inflammation of the conjunctiva. The conjunctiva is a thin membrane that lines the inner surface of the eyelids and the skin of the pupils (called the sclera). Conjunctivitis can affect both children and adults. The most common signs of conjunctivitis include red eyes and discharge.

There are several possible causes of conjunctivitis, including bacterial or viral diseases, asthma, or an unspecific disorder (eg, a foreign body in the eye). All cases with conjunctivitis include a red eye, but not everyone with a red eye has conjunctivitis.



Viral conjunctivitis is usually caused by a virus that may often induce common colds. An individual may experience symptoms of conjunctivitis alone or as part of a general cold syndrome, with swollen lymph nodes (glands), fever, sore throat, and runny nose. Viral conjunctivitis is very infectious. It is transmitted by touch, usually with items that have come into contact with the eye secretions of the infected person. The most frequent signs of viral conjunctivitis include redness, aqueous or mucus discharge, and an itching, sandy or cracking pain in one eye. Some may have morning crusting followed by a watery discharge, maybe with few mucus discharges during the day. The second eye is typically affected within 24 to 48 hours.

There's no treatment for viral conjunctivitis. Recovery may begin within days, but symptoms always intensify for the first three to five days, with steady progress for the next one to two weeks for a period of two to three weeks.


Bacterial conjunctivitis is particularly infectious, frequently involving several family members. Bacterial conjunctivitis is transmitted by touch, usually with items that have come into contact with an infected person's eye secretions. As an example, the bacteria will be spread when an infected person contacts his or her eye and then touches another surface (e.g. a door handle) or shares an object that has touched his or her eye (eg, a towel or pillow case) (eg, a towel or pillow case).

The most common signs of bacterial conjunctivitis include redness and thick discharge from one eye, while both eyes may become infected. The discharge can be yellow, white or green, and usually begins to drain during the day. The affected eye is sometimes "stuck shut" in the morning.


Many forms of bacterial conjunctivitis heal rapidly and do not cause permanent damage when treated with antibiotic eye drops or ointment.


Allergic conjunctivitis is caused by respiratory allergens that come into contact with the skin. Symptoms (most often redness, watery drainage, and itching in both eyes) can be sudden onset (acute), seasonal, or present all year round (perennial), depending on the allergen.


Toxic conjunctivitis also known as toxic keratoconjunctivitis is a chronic irritation of the surface of the skin by an interfering agent, generally a preservative or a drug.


It is possible to experience a red eye and discharge that is not caused by inflammation, allergy or toxicity. The most common causes include one of the following:

  • A person with a dry eye may have chronic or intermittent redness or discharge.

  • A person whose eyes are irrigated after a chemical splash can have redness and discharge.

  • A person with a foreign body (e.g. mud, eyelash) in the eye may have redness and discharge for 12 to 24 hours after the substance has been removed.


Bacterial and viral conjunctivitis are both highly contagious and spread by direct contact with secretions or contact with contaminated objects. Below are typical hygiene measures used to minimize transmission to others:

  • Adults or children with bacterial or viral conjunctivitis should not share handkerchiefs, tissues, towels, cosmetics, or bedsheets/pillows with uninfected family or friends.

  • Hand washing is an important and highly efficient way to prevent infection from spreading. Hands should be damp with water and plain soap and rub together for 15 to 30 seconds. Antibacterial hand soap is not needed. Teach children to wash their hands before and after feeding and rubbing their eyes, coughing or sneezing.

  • Alcohol-based hand rubs are a suitable substitute for hand disinfection if a sink is not available. Hand rubs may be applied over the whole surface of the palms, fingertips, and wrists until they are dry, and can be used several times.

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