Conjunctivitis is one of the most common clinical eye diseases. Usually, when the conjunctival defenses are weak, an inflammatory response is induced once external irritation occurs, leading to the development of conjunctivitis. Once the symptoms of conjunctivitis are detected, it is important to take active steps to treat them and help maintain eye health. The causes of conjunctivitis can be divided into two main categories. The first category is infectious, which is caused by infection with pathogenic microorganisms such as bacteria and viruses, and is the most common in clinical practice. The other category is non-infectious, which includes allergic reactions, physical and chemical factors, and dry eyes due to irritation induced conjunctivitis. Itching, burning, stinging sensation, conjunctival congestion, visual fatigue, and increased discharge are typical clinical manifestations of conjunctivitis. Conjunctivitis does not usually cause blurred vision, but when inflammation involves the cornea, it may affect the ability to see normally. Conjunctivitis is primarily treated clinically with medications. For bacterial conjunctivitis, antibiotic eye drops can be used to help relieve and control the symptoms. Commonly used clinical eye drops include rifampin and erythromycin drops. Viral conjunctivitis requires antiviral eye drops. For patients with allergic conjunctivitis, the oral anti-allergy drug loratadine should be taken to help reduce symptoms. Understanding the causes, clinical manifestations and treatment of conjunctivitis can help prevent and treat conjunctivitis and maintain eye health.