The top 15 most common medical emergencies include cardiac arrest, stroke, seizures, diabetic emergencies, anaphylaxis, drowning, drug overdose, heatstroke, hypothermia, asthma attacks, choking, severe bleeding, head injury, fractures, and burns. To identify them, look out for signs such as chest pain, sudden loss of consciousness, difficulty breathing, severe headache, seizures, changes in skin color, or excessive bleeding.