Pink eye (or conjunctivitis) is a common cause of a red eye.  Conjunctivitis means there is inflammation – swelling and redness – of the thin layer of tissue that covers the eye and the inside of the eyelid.  

There are different kinds of conjunctivitis, and not all of them are caused by a bacterial infection.  All of the types of conjunctivitis cause a red eye, but all red eyes are not caused by conjunctivitis.  I will focus mainly on bacterial and viral conjunctivitis for the purpose of this post.  

Types of Conjunctivitis

The two main causes of conjunctivitis are bacterial or viral infections.  Viral infections are common in both children and adults and the most common culprit for conjunctivitis.

Other causes include allergic conjunctivitis, chemical conjunctivitis and other immune mediated causes. 

Signs and Symptoms of Conjunctivitis

Bacterial conjunctivitis is the cause of the characteristic “pink eye” infection we all know so well.  It most commonly presents as:

• Red (or pink), itchy and painful eye(s)
• Can be one or both eyes
• Green or yellow discharge
• Eyes can be crusted shut in the mornings

Viral conjunctivitis is more common than bacterial.  Its symptoms are different than bacterial and include:

• Pink, swollen, watery eye(s)
• May only affect one eye

Bacterial conjunctivitis is very contagious

It spreads very easily through direct contact from person to person.  It also spreads very easily from contaminated surfaces or from droplets. 

Treatment of Conjunctivitis

Only bacterial conjunctivitis should be treated with an antibiotic drop or ointment. Any concerns for eye infection should be evaluated by a physician to determine the cause for the red eye. See your care provider urgently if symptoms include decreased vision, light sensitivity, severe pain or trauma.

In most cases, conjunctivitis self limited and will resolve within 5 or 6 days, even without antibiotics.  Antibiotics will help shorten the duration of the bacterial infection and is needed for some types of infections (ie. gonorrhea or chlamydia and conjunctivitis in contact lens wearers).  

Wash your hands often, especially when touching the eyes, nose and mouth to prevent the spread of conjunctivitis.  

This post was co-authored by Erin Manchuk, BScPharm, BCGP and Stephanie Liu, MD, MSc, CCFP, BHSc.