Many conditions can cause bleeding from the sensitive tissue in the lungs. Many blood vessels lie under the inside surface of the lung tissue. Injury, infection or inflammation can irritate the blood vessels and cause hemoptysis.

Common causes for hemoptysis include:

• Blood thinners
• Acute bronchitis
• COPD
• Pneumonia
• Tonsillitis

Less common causes for hemoptysis include:

• Bronchiectasis
• Bronchoscopy
• Congestive heart failure
• Cystic fibrosis
• Dengue
• Drug side effect
• Factor 10 deficiency
• Factor 2 deficiency
• Factor 5 deficiency
• Factor 7 deficiency
• Fungal lung infection
• Goodpasture's syndrome
• Hemophilia
• Laryngeal cancer
• Laryngoscopy
• Lung abscess
• Lung biopsy
• Lung cancer
• Lupus
• Mitral valve stenosis
• Mediastinoscopy
• Oral cancer
• Pulmonary contrusion
• Pulmonary edema:
• Congestive heart failure
• Pulmonary embolism
• Surgery
• Thoracoscopy
• Tuberculosis
• Von Willebrand's disease
• Wegener's granulomatosis