Exposure to an allergen for allergic conjunctivitis is a risk factor, as is exposure to someone infected with the viral or bacterial form of conjunctivitis. Both viral and bacterial conjunctivitis are common among children and are very contagious. Someone with conjunctivitis may be contagious for seven to 14 days after signs and symptoms first appear.

Conjunctivitis can be an irritating condition, but it's usually harmless to sight and typically doesn't require extensive or emergency treatment. Yet because conjunctivitis can be highly contagious for as long as two weeks after signs and symptoms begin, it's important to seek diagnosis and treatment early. Keep children with bacterial conjunctivitis away from child-care facilities or school until after they start treatment. Children with viral conjunctivitis are usually contagious for a few days. Check with your doctor if you have any questions about when your child can return to school or child care. Occasionally conjunctivitis can cause corneal complications in adults and children, making early treatment even more important.