The blood can come from the nose, mouth, throat, the airway passages leading to the lungs, or the lungs. Blood-tinged mucus in a healthy nonsmoker usually indicates a mild infection and is generally no cause for concern. In patients with a history of smoking or who are otherwise at risk for lung disease, however, hemoptysis is often a sign of serious illness, including cancer. Hemoptysis can also result from inhaling a foreign body, such as a particle of food that ruptures a blood vessel. Whatever the suspected cause, development of hemoptysis should always be brought to the attention of a physician.
Hemoptysis refers specifically to blood that comes from the respiratory tract.
Often when a person spits up blood, however, it has come from somewhere else - the nose, the back of the throat, or part of the gastrointestinal tract. Vomiting up blood, medically known as hematemesis , is one type of pseudohemoptysis. Differentiating between hemoptysis and hematemesis is an integral part of diagnosis. If there is a small amount of blood or sputum streaked with blood, the spitting is considered mild hemoptysis. But even in cases of mild hemoptysis, a patient may suffer critical breathing problems, depending on the underlying cause of the bleeding.