The early symptoms of pulmonary embolism are clinically diverse and often non-specific. Mild cases may not present any symptoms at all. Common symptoms include the following: 1. Unexplained difficulty in breathing; 2. Pain in the precordial region; 3. Some patients initially present with fainting as the first clinical symptom; 4. Some patients may also experience irritability, fear, or a near-death feeling; 5. Early symptoms can also include coughing, coughing up blood, and palpitations. Pulmonary embolism is a critical condition in clinical settings. Once it occurs, it is essential to go to the hospital promptly for an accurate diagnosis and to receive effective treatment to avoid severe clinical consequences.