Conjunctivitis can be determined as bacterial or viral by eye symptoms, causative agent, and infectiousness. 1. Eye symptoms: Bacterial conjunctivitis eye discharge is yellow, green or yellow-green, while viral conjunctivitis eye discharge is mostly watery or thin. 2. Causative agent: Bacterial conjunctivitis is caused by bacteria, commonly staphylococcus, Pseudomonas aeruginosa, etc., while viral conjunctivitis is caused by viral infections, commonly adenovirus, coxsackievirus, etc.. 3. Contagious: viral conjunctivitis is highly contagious, while bacterial conjunctivitis is also contagious, but weaker. Conjunctivitis should be treated in a timely manner by a doctor who will evaluate and make a diagnosis.