There are various types of conjunctivitis, all of which involve inflammation of the conjunctiva on the sclera.

Many types of bacteria such as Staphylococcus aureus, Haemophilus influenzae, and Streptococcus pneumoniae may lead to bacterial conjunctivitis, which is the most common type. These bacteria can be spread through human contact, contaminated surface, sinus and ear infection. Besides common symptoms such as pink eye, bacterial conjunctivitis usually produces a thick discharge or pus. Antibiotics are usually used to treat bacteria conjunctivitis.

Viral and bacterial conjunctivitis can be relieved by warm compress and eye drops or pills are used to treat allergic conjunctivitis. Different types of conjunctivitis have different symptoms and require different treatments.