The blood can come from the nose, mouth, throat, the airway passages leading to the lungs, or the lungs themselves. Blood-tinged mucus in a healthy nonsmoker usually indicates only a mild infection and is generally no cause for concern. In patients who have a history of smoking or are otherwise at risk for any underlying lung disease, however, hemoptysis is often a sign of serious illness, including cancer. Hemoptysis can also result from breathing in a foreign body, such as a particle of food that pokes and ruptures a blood vessel. Whatever the suspected cause, development of hemoptysis should always be brought to the attention of the person's physician.
Hemoptysis refers specifically to blood that comes from the respiratory tract.
Often when a person spits up blood, however, they re spitting up something that has come from somewhere else - the nose, the back of the throat, or some 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 only a small amount of blood or whitish yellow 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.