Dizziness at the sight of blood is mainly a problem of hematemesis, which has the following causes: 1. The underlying cause is too much anxiety, tension or even excessive fear, there may be a series of manifestations such as dizziness, panic and even unconsciousness. If you have very serious tension and anxiety, you must actively treat and intervene. 2. It may also be a bad conditioned reflex, such as seeing a bloody event or scene as a child, which may also cause a traumatic experience causing a certain psychological shadow, and it is possible that you will faint when you see blood after you grow up, and you may even experience nausea, vomiting, irritability, anxiety and other such manifestations. 3. It is also possible that some people have an aversion to blood. Blood aversion reaction, for example, because the sight of blood is associated with particularly bad things, or even think of death or massacre, it is likely to see blood will have a variety of negative emotions, and even appear unconscious, fainting and other serious problems.