Red eyes can be caused by eye fatigue, foreign objects in the eyes, eye diseases and other factors. 1. Eye fatigue: long time looking at the computer or cell phone may lead to overuse of the eyes, making the eyes overworked, which will lead to redness and bloodshot eyes, and there may also be dry eyes, tearing and other symptoms. 2. Foreign objects in the eyes: foreign objects in the eyes, such as small insects or eyelashes, can cause local irritation, which will lead to redness and bloodshot eyes, and may be accompanied by frequent blinking or inability to open the eyes. 3. Eye diseases: such as conjunctivitis, keratitis, glaucoma and other diseases, will lead to eye abnormalities, such as eye redness, blood, pain, itching, tearing and so on. You should avoid excessive use of the eyes in daily life. When the symptoms of redness and bloodshot eyes persist and cannot be relieved by resting, and are accompanied by other abnormal symptoms, it is recommended to consult a doctor so as to avoid delaying the condition, which may have an adverse effect on your eyesight.