| Lungs | No symptoms/signs | 0 |
| Difficulty in breathing, mild chest tightness, mild discomfort, breathing 20-25 times/min | 1 |
| Moderate respiratory distress (dyspnea, 26-40 breaths/min, use of auxiliary respiratory muscles) | 2 |
| Cyanosis, feeling of insufficient air, severe shortness of breath, or respiratory distress/failure | 3 |
| Cardiovascular | No symptoms/signs | 0 |
| Heart rate 100-125 beats/min, palpitations, general fatigue, benign arrhythmia or hypertension | 1 |
| Heart rate 126-175 beats/min or hypotension (systolic blood pressure <100 mmHg) | 2 |
| Heart rate >175 beats/min or hypotension (systolic blood pressure <100 mmHg), malignant arrhythmia, or cardiac arrest | 3 |
| Local trauma | No symptoms/signs (swelling or erythema around the teeth mark <2.5 cm) | 0 |
| Pain, swelling or bruising of the bite area <5.0-7.5 cm | 1 |
| Pain, swelling or bruising of the bite area not extending beyond half of the limb (7.5-50.0 cm) | 2 |
| Pain, swelling or bruising of the bite area extending over half of the limb (50-100 cm) | 3 |
| Pain, swelling or bruising beyond the limb (> 100 cm from the bite site) | 4 |
| Gastrointestinal tract | No symptoms/signs | 0 |
| Abdominal pain, tenesmus, or nausea | 1 |
| Vomiting or diarrhea | 2 |
| Repeated vomiting, diarrhea, hematemesis, or hematochezia | 3 |
| Hematology | No symptoms/signs | 0 |
| Mild changes in coagulation parameters (PT < 20 s, APTT < 50 s, platelet count (100-150) × 10⁹/L, fibrinogen 100-150 mg/dL) | 1 |
| Significantly abnormal coagulation parameters (PT 20-50 s, APTT 50-75 s, platelet count (50-100)×10⁹/L, fibrinogen 50-100 mg/dL) | 2 |
| Significantly abnormal coagulation parameters (PT 50-100 s, APTT 75-100 s, platelet count (20-50)×10⁹/L, fibrinogen <50 mg/dL) | 3 |
| Significantly abnormal coagulation parameters, accompanied by severe bleeding or spontaneous bleeding risk; PT or APTT undetectable, platelet < 20×10⁹/L, fibrinogen undetectable, other laboratory results with severe abnormalities such as abnormal venous blood coagulation time | 4 |
| Nervous system | No symptoms/signs | 0 |
| Mild anxiety or fear, headache, fatigue, dizziness, coldness, or abnormal sensation | 1 |
| Moderate anxiety or fear, headache, fatigue, dizziness, chills, confusion or blurring of consciousness, muscle tremors or fasciculations in the bite area, ptosis of the upper eyelid, and difficulty swallowing | 2 |
| Severe confusion, lethargy, weakness, paralysis, convulsions, coma, mental disorders, or generalized muscle fasciculations | 3 |
| Kidney | Normal creatinine and urine volume | 0 |
| Creatinine 1.5-1.9 times the baseline, or creatinine increases by ≥26.5 μmol/L, or urine volume <0.5 mL/(kg·h)for >6 h | 1 |
| Creatinine 2.0-2.9 times the baseline, or urine volume less than 0.5 mL/(kg·h) for > 12 h | 2 |
| Creatinine ≥3 times the baseline, creatinine ≥353.6 µmol/L, urine volume <0.3 mL/(kg·h) for >24 h, or anuria ≥12 h, or requiring renal replacement therapy | 3 |