Bloodshot eyes may be associated with conjunctivitis, iridocyclitis, acute glaucoma and infective endocarditis, etc. It is recommended to go to the hospital for timely consultation. 1. Conjunctivitis: It can be caused by microbial infection, allergic reaction and other factors, which not only manifests bloodshot eyes, but also accompanied by discomfort symptoms such as increased ocular discharge and foreign body sensation. 2. Iridocyclitis: caused by infection, trauma, autoimmunity and other factors, the above symptoms can also occur, as well as photophobia, tearing and even vision loss. 3. Acute glaucoma: due to inflammation, trauma and other factors, the intraocular pressure can rise suddenly, resulting in eye congestion, eye pain, vision loss, etc. In severe cases, permanent damage to vision can occur. 4. Infective endocarditis: some people show ocular complications and subconjunctival hemorrhagic spots, resulting in the above symptoms. It is recommended to go to the hospital in time to avoid delaying the condition.