Shock can be caused by any condition that reduces blood flow, including:

Heart problems (such as heart attack or heart failure)

Low blood volume (as with heavy bleeding or dehydration)

Changes in blood vessels (as with infection or severe allergic reactions)

Certain medicines that significantly reduce heart function or blood pressure

Shock is often associated with heavy external or internal bleeding from a serious injury. Spinal injuries can also cause shock.

Toxic shock syndrome is an example of a type of shock from an infection.