The common causes of bloodshot eyes are eye fatigue, conjunctivitis and other causes. 1. Visual fatigue of the eyes: staying up late for a long time and watching electronic products with radiation such as cell phones and computers for a long time will result in conjunctival congestion of the eyes, which is sometimes accompanied by the symptoms of dry eyes and astringency. 2. Conjunctivitis: usually due to bacterial infection, allergies, external environmental stimuli such as inflammation, while conjunctivitis can cause subconjunctival hemorrhage phenomenon, such as color changes around the eye is the most common symptom. Different causes require different treatment methods. Need to pay attention to eye hygiene, can be treated with medication under the guidance of a doctor; usually pay attention to eye hygiene, rest, avoid excessive eye use, avoid spicy cold diet, eat more food containing vitamin A, actively exercise to increase the body’s resistance, pay attention to the usual rules of life. There are other causes of bloodshot eyes, it is recommended to go to the regular hospital in time.