A cough, also known as tussis, is a voluntary or involuntary act that clears the throat and breathing passage of foreign particles, microbes, irritants, fluids, and mucus; it is a rapid expulsion of air from the lungs.RespiratoryEncyclopedia Entry for Coughing :Coughing up blood. Coughing up blood is not the same as bleeding from the mouth, throat, or gastrointestinal tract. Blood that comes up with a cough often looks bubbly because it is mixed with air and mucus. It is most often bright red, although it may be rust-colored. Sometimes the mucus contains only streaks of blood. The outlook depends on what is causing the problem. Most people do well with treatment to treat the symptoms and the underlying disease. People with severe hemoptysis may die.A number of conditions, diseases, and medical tests may make you cough up blood. These include: Blood clot in the lung Breathing food or other material into the lungs (pulmonary aspiration) Bronchoscopy with biopsy Bronchiectasis Bronchitis Cancer Cystic fibrosis Inflammation of the blood vessels in the lung (vasculitis) Injury to the arteries of the lungs Irritation of the throat from violent coughing (small amounts of blood) Pneumonia or other lung infections Pulmonary edema Systemic lupus erythematosus Tuberculosis Very thin blood (from blood thinning medications, most often at higher than recommended levels).Medicines that stop coughing (cough suppressants) may help if the problem comes from heavy coughing. These medicines may lead to airway blockages, so check with your health care provider before using them. Keep track of how long you cough up blood, and how much blood is mixed with the mucus. Call your provider any time you cough up blood, even if you do not have any other symptoms.Get medical help right away if you cough up blood and have: A cough that produces more than a few teaspoons of blood Blood in your urine or stools Chest pain Dizziness Fever Lightheadedness Severe shortness of breath.In an emergency, your provider will give you treatments to control your condition. The provider will then ask you questions about your cough, such as: How much blood are you coughing up? Are you coughing up large amounts of blood at a time? Do you have blood-streaked mucus (phlegm)? How many times have you coughed up blood and how often does it happen? How long has the problem been going on? Is it worse at some times such as at night? What other symptoms do you have? The provider will do a complete physical exam and check your chest and lungs. Tests that may be done include: Bronchoscopy , a test to view the airways Chest CT scan Chest x-ray Complete blood count Lung biopsy Lung scan Pulmonary arteriography Sputum culture and smear Test to see if the blood clots normally, such as PT or PTT.Hemoptysis; Spitting up blood; Bloody sputum.Brown CA, Raja AS. Hemoptysis.