The presence of a blood-like or metallic taste in the mouth following exercise can be attributed to extreme stress on the pulmonary capillaries which form the blood-gas barrier in the lung, according to the U.S. National Library of Medicine National Institute of Health.
When these capillaries are stressed to the point of breaking the collagen barrier, an athlete may experience bleeding in the lung. This condition, called an exercise-induced pulmonary hemorrhage, typically occurs in elite athletes exercising at maximum capacity, according to the National Institute of Health or NIH. The condition generally does not cause permanent damage; and, it can be remedied by lowering the level of exertion.
Additional causes of a bloody taste following exercise include poor oral hygiene, exercise-induced anaphylaxis or high dosages of medications or supplements, according to Live Well at Jillian Michaels. If poor oral hygiene is to blame, the taste would likely be present at other times. However, because exercise can cause a dry mouth, the taste can become more apparent, according to Live Well at Jillian Michaels.
Exercise-induced anaphylaxis is a more serious condition in which the body suffers an allergic reaction to exercise. While rare, this condition can progress into more serious symptoms, including hives, swelling and loss of consciousness, states Live Well at Jillian Michaels. In this case, it is vital to seek immediate medical help.