The question appears in nearly every CPR course, and the answer is short: immediately, before starting compressions. What makes it worth understanding rather than memorizing is the reasoning, because the sequence is different for a child, and knowing why protects you from applying the wrong one under pressure. This guide covers the answer, the logic behind it, and the practical steps around it.
Get Trained
Before anything else, the most useful thing this article can tell you is that reading about resuscitation is not a substitute for a course.
Hands-on training with an instructor and a manikin teaches compression depth, rate, and hand position in a way text cannot. Certification courses are widely available through the American Heart Association, the American Red Cross, and equivalent organizations in other countries, and many run in a few hours.
If you are reading this because you want to be prepared, book a class. If you are reading it during an emergency, call emergency services now and follow the dispatcher’s instructions, which will include compression guidance.
The Direct Answer
For adults/adolescents, you should call/activate EMS immediately upon finding an unresponsive person, before beginning CPR.
This is often summarized in training as call first for adults and adolescents, contrasted with care first for infants and young children in certain circumstances.
The instruction to activate emergency services first applies once you have established that the person is unresponsive and not breathing normally. In the United States that means calling 911, and in other countries the equivalent local emergency number.
Why the Order Matters
Understanding the reasoning makes the rule stick, and the logic is genuinely straightforward.
In adults and adolescents, sudden collapse is most commonly caused by a cardiac problem, frequently a lethal arrhythmia such as ventricular fibrillation. The definitive treatment for that is defibrillation, delivering a shock that allows the heart to resume an organized rhythm.
CPR keeps blood and oxygen circulating, which buys time. It does not usually restart the heart on its own. What restarts the heart is a defibrillator.
That means the single most valuable thing you can do early is get a defibrillator and trained responders on the way. Every minute without defibrillation reduces the chance of survival substantially, so the clock starts when the call is made.
This is the entire reason that for adults/adolescents, you should call/activate EMS before starting compressions rather than after.
Why Children Are Different
The contrast explains the rule better than the rule alone.
In infants and young children, cardiac arrest is more commonly caused by a respiratory problem, such as choking, drowning, or breathing failure, which then leads to the heart stopping.
In that situation the immediate need is oxygen rather than a shock. Guidelines therefore direct a lone rescuer with no phone available to provide about two minutes of CPR first, then leave to call for help, on the basis that early ventilation and compressions address the actual cause.
The practical summary taught in courses is that for adults/adolescents, you should call/activate EMS first, while for infants and prepubescent children a lone rescuer without a phone gives care first.
The Modern Complication: Phones
An important update that changes the calculation in most real situations.
The call-first and care-first distinction was developed when calling meant physically leaving the person to find a telephone. Mobile phones changed that entirely.
Current guidance is that if you have a mobile phone, you should call emergency services and put the phone on speaker while beginning CPR, so you are doing both simultaneously rather than choosing between them.
If bystanders are present, the sequence is simpler still. Direct one specific person to call emergency services and another specific person to find an AED, using clear individual instructions rather than a general appeal to the group.
Pointing at someone and saying “you, call 911, and tell me when you have” is meaningfully more effective than “someone call 911,” which frequently results in everyone assuming someone else did.
The Full Sequence
Putting it together, the standard adult sequence taught in courses, in which for adults/adolescents, you should call/activate EMS early, runs as follows:
- Check the scene is safe. You cannot help anyone if you become a casualty.
- Check responsiveness. Tap the shoulders firmly and shout.
- Check breathing. Look for normal breathing for no more than about ten seconds. Occasional gasping is not normal breathing and should be treated as absent.
- Activate EMS and get an AED. Call directly or direct specific bystanders.
- Begin chest compressions. Push hard and fast in the center of the chest.
- Use the AED as soon as it arrives, following its spoken prompts.
- Continue until emergency responders take over, the person shows signs of life, or you are physically unable to continue.
Agonal Gasping
This deserves specific attention because it causes people to hesitate at exactly the wrong moment.
Agonal breathing is an irregular, gasping, snoring, or gurgling pattern that can occur in the first minutes of cardiac arrest. It looks like breathing, and bystanders frequently interpret it as a sign the person is alive and does not need CPR.
It is not effective breathing. Guidelines are explicit that agonal gasps should be treated as absent breathing, and CPR should begin.
If you are unsure whether breathing is normal, the guidance is to act as though it is not. The risk of performing compressions on someone who did not need them is considerably lower than the risk of withholding them from someone who did.
What to Tell the Dispatcher
Once you have established that for adults/adolescents, you should call/activate EMS and you are on the line, the dispatcher needs specific information quickly:
| Information | Why it matters |
|---|---|
| Exact location | Dispatch cannot help without it |
| What happened | Determines the response sent |
| Person’s approximate age | Affects protocols |
| Whether they are breathing | Triggers CPR instructions |
| Whether an AED is available | Guides bystander direction |
| Your callback number | For follow-up if disconnected |
Give the location first. If the call drops for any reason, that is the piece of information that still allows help to arrive.
Then stay on the line. Dispatchers in most systems provide real-time CPR coaching, including counting a compression rate, and that guidance measurably improves outcomes for people with no training.
Hands-Only CPR
Worth knowing because it removes a common barrier.
For untrained bystanders responding to an adult who collapses suddenly, the guidance is hands-only CPR: continuous chest compressions without rescue breaths.
The reasoning is that untrained rescuers frequently hesitate over mouth-to-mouth, and that hesitation costs time. Compressions alone are substantially better than nothing, and for the first several minutes of a cardiac arrest the blood still contains usable oxygen.
Push in the center of the chest, hard and fast, at a rate of about 100 to 120 compressions per minute, allowing the chest to recoil fully between compressions.
Trained rescuers may add rescue breaths in a ratio taught in their course.
Using an AED
Automated external defibrillators are designed for untrained users and are increasingly common in public buildings, transport hubs, gyms, and workplaces.
The device gives spoken instructions. It analyzes the heart rhythm and will only advise a shock if one is appropriate, which means it cannot shock someone who does not need it.
Turn it on, follow the prompts, apply the pads to bare skin as the diagram shows, ensure nobody is touching the person during analysis and shock, and resume compressions immediately afterward.
Do not delay compressions to search for an AED if you are alone without a phone. Send someone else if anyone is available.
Good Samaritan Considerations
A common hesitation worth addressing briefly. Many jurisdictions have laws providing legal protection to bystanders who provide reasonable assistance in good faith during an emergency.
The specifics vary considerably by state and country, and this is not legal advice. The practical point is that fear of liability is a widely cited reason bystanders hesitate, and in most places those protections exist precisely to remove that barrier.
Why This Question Appears in Training
The reason the phrasing that for adults/adolescents, you should call/activate EMS shows up in courses is that the sequence genuinely changes outcomes.
Survival from out-of-hospital cardiac arrest depends heavily on how quickly defibrillation occurs. Bystander action, meaning early recognition, early call, and early compressions, is the difference between a survivable event and a fatal one in a large proportion of cases.
Courses teach the sequence as a fixed rule because under stress people do not reason from first principles. They fall back on what they practiced.
The bottom line is that for adults/adolescents, you should call/activate EMS immediately upon finding an unresponsive person who is not breathing normally, before starting chest compressions, because sudden collapse in this age group is usually cardiac and the definitive treatment is defibrillation. If you have a mobile phone, call and use speaker while starting compressions. If bystanders are present, assign specific individuals to call and to fetch an AED. For infants and young children, a lone rescuer without a phone provides about two minutes of care first, since the cause is more often respiratory. Treat agonal gasping as absent breathing, and take a certified course, since hands-on training is what makes any of this work under pressure.
Key Takeaways
- For adults and adolescents, activate EMS immediately on finding an unresponsive person, before starting CPR.
- Training summarizes this as call first for adults, contrasted with care first for young children.
- Adult collapse is usually cardiac, and the definitive treatment is defibrillation rather than compressions.
- CPR circulates blood and buys time but does not typically restart the heart on its own.
- For infants and prepubescent children, arrest is more often respiratory, so a lone rescuer gives two minutes of care first.
- With a mobile phone, call emergency services on speaker while beginning compressions rather than choosing.
- Assign specific individuals to call and to fetch an AED, since general appeals to a crowd often fail.
- Agonal gasping is not normal breathing and should be treated as absent breathing.
- Untrained bystanders should use hands-only CPR at 100 to 120 compressions per minute.
- AEDs give spoken instructions and only advise a shock when the rhythm requires one.
- Give the dispatcher your exact location first, then stay on the line for CPR coaching.
- Reading about CPR is not a substitute for a certified hands-on course.
