Coughing with cold and coughing up sputum with blood or blood clots can have several causes: First, bright red blood in the sputum is mostly seen in tuberculosis or bronchial dilatation. Sometimes there is inflammation in the pharynx, and this phenomenon can also occur. Second, black blood sputum is mostly seen in pulmonary embolism. Third, coughing up bleeding foam-like sputum is seen in pulmonary edema. Fourthly, if there is blood in sputum for a long time or accompanied by chest pain, weakness and wasting, you should be alert to bronchial lung cancer. Blood in sputum is a serious symptom and should be seen by a doctor immediately if it occurs. The underlying cause may or may not be serious, so it is important to go to the hospital for a systematic examination. Sometimes bleeding gums and nose bleeds can be mistaken for blood in sputum.