The first few minutes after an injury or medical crisis occurs are frequently the most important.

The American College of Emergency Physicians has identified the following warning signs of a medical emergency:
- Difficulty breathing, shortness of breath
- Chest or upper abdominal pain or pressure
- Fainting, sudden dizziness, weakness
- Changes in vision
- Confusion or changes in mental status
- Any sudden or severe pain
- Uncontrolled bleeding
- Severe or persistent vomiting or diarrhea
- Coughing or vomiting blood
- Suicidal or homicidal feelings

Review this list with your physician and ask whether there are other warning signs you should watch for, because other factors, such as previous medical problems, may be important. In addition, ask when you should call the doctor's office vs. go straight to an emergency department or call an ambulance. Find out what you should do when the doctor's office is closed.

When to Call 911
Always call EMS if the victim needs immediate medical treatment. To make this decision, ask yourself the following questions:

Is the victim's condition life-threatening?

Could the victim's condition worsen and become life-threatening on the way to the hospital?

Does the victim require the skills or equipment of paramedics or emergency medical technicians?

Could the distance or traffic conditions cause a delay in getting the victim to the hospital?

If you answer to any of these questions is "yes," or if you are unsure, it is best to call EMS. Paramedics and emergency medical technicians can begin medical treatments at the scene and on the way to the hospital and alert the emergency department of your condition en route.

When you call for help, speak calmly and clearly. Give your name, address and phone number; give the location of the victim; and describe the problem. Don't hang up until the dispatcher tells you to, because he or she may need more information or need to give you instructions.

- From the American College of Emergency Physicians