No infection, but coughing with blood, why?

Hemoptysis: Blood can enter into airsacs of the lungs from the pulmonary arteries (air exchange system)or from the blood vessels that feed the lung structures. Bleeding may result from dry air; diseases in the airways (cancer, infection, a foreign body, a connection between a blood vessel and the airway) or tissues (infection, immune disorders, Cocaine damage); blood vessel or bleeding disorder. See a doc!