The conjunctiva, which contains tiny blood vessels, produces mucus to keep the surface of your eye moist and protected. When the conjunctiva becomes irritated or swollen, the blood vessels become larger and more prominent, making your eye appear red. Signs of pink eye may occur in one or both eyes. 

There are three types of conjunctivitis:  

Bacterial conjunctivitis

This is a highly contagious form of pink eye caused by bacterial infections. This type of conjunctivitis usually causes a red eye with a lot of pus.  

Viral conjunctivitis

The most common cause of pink eye is the same virus that causes the common cold, and is also very contagious.  

Allergic Conjunctivitis
Allergic conjunctivitis

Allergic conjunctivitis

This form of conjunctivitis is caused by the body's reaction to an allergen or irritant. It is not contagious.  


Written by
Reviewed by Dr. Elena Jiménez on Feb. 1, 2014

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