Conjunctivitis is the most common disease of the eye. To treat conjunctivitis, the first step is to find the cause. There are many causes of conjunctivitis, the most common being microbial infections, which may be bacterial, viral, or chlamydial, and occasionally fungal, rickettsial, and parasitic infections can be seen. Some are caused by physical irritation or chemical damage, such as sand, smoke, ultraviolet light, or toxic gases and fluids. Some cases of conjunctivitis may be due to immune pathology, such as allergic reactions, systemic diseases, or the spread of inflammation from adjacent tissues, such as keratitis or sclerositis. Identification of the cause is the key, and treatment is usually required to address the cause. For bacterial conjunctivitis, antibiotic eye drops/ointment is the main treatment in the acute stage; for viral conjunctivitis, antiviral eye drops are the main treatment; for trachoma caused by Chlamydia trachomatis, rifampicin and aureomycin eye drops/ointment are the main treatment. In case of allergic conjunctivitis, treatment with anti-allergic eye drops is required. Local drops and ointments are usually used for treatment, and systemic treatment is not used without special circumstances. Most types of conjunctivitis are cured without complications, but a few have some vision loss due to complications of corneal inflammation. Some patients may also have a legacy of dry eye. Therefore, people should try to pay attention to washing their hands more often and develop good hygiene habits to prevent it first.