Conjunctivitis means inflammation of the conjunctiva which is a layer of the eye. This layer is present but is not usually inflamed or red.
The vast majority of the cases occur in association with a cold and are caused by a virus. They are self-limited and will resolve within two weeks without treatment. The other causes are bacterial which will be improved with an antibiotic, allergic, chemical cover the vast majority of cases. The viral and bacterial forms are contagious so one should not share towels nor use other items to cleanse their eyes etc that could have been used by someone else who has this disease. Most schools and day cares will not allow one with conjunctivitis to attend because of the risk of spread.
Anyone with a very irritated or pink eye who wears contact lenses should see their doctor for evaluation and treatment. The possibility of corneal ulcers is the danger in this group.
Viral conjunctivitis will not be improved with the administration of antibiotics and is self limited. These cases will usually be associated with a cold and will start off unilaterally. They will then usually spread to the contralateral eye. There will be discharge from the eye that can be copious.
Bacterial conjunctivitis can be treated with antibiotics and this will shorten the amount of time one is contagious but this is a minority of the cases. There can be copious discharge from the eyes.
Allergic and chemical causes should be carefully assessed so that the causes can be determined and either avoided or appropriate anti-allergic medications can be given.