Mouth-to-mouth resuscitation delivers your exhaled breath into another person’s lungs when they’ve stopped breathing. Each breath should last about 1 second and deliver just enough air to make the chest visibly rise. Here’s exactly how to do it, step by step, for adults, children, and infants.
How Mouth-to-Mouth Breathing Works
The air you breathe out still contains about 16 to 17% oxygen, down from the 21% in room air. That’s enough to keep someone’s organs alive when they can’t breathe on their own. Your exhaled breath isn’t ideal, but it buys critical time until emergency help arrives.
Step-by-Step for Adults
Before giving breaths, you need to open the airway. With the person lying face up on a firm surface, place one hand on their forehead and the fingertips of your other hand under the bony part of their chin. Tilt the head back gently while lifting the chin forward. This pulls the tongue away from the back of the throat. In studies, this head-tilt, chin-lift technique opened a blocked airway successfully in about 91% of patients.
Once the airway is open:
- Pinch the nose shut with the hand that’s on the forehead.
- Seal your mouth completely over theirs.
- Blow steadily for 1 second, watching the chest. You want to see visible rise, not a dramatic inflation. The actual volume needed is surprisingly small, roughly 350 to 400 milliliters, or about what would fill a small water bottle.
- Break the seal, turn your head to the side, and let the chest fall as air escapes passively.
- Give a second breath the same way.
If the person has a pulse but isn’t breathing, give 1 breath every 6 seconds (10 breaths per minute) and keep checking for a pulse every 2 minutes. If there’s no pulse, pair the breaths with chest compressions: 30 compressions followed by 2 breaths, repeating until help arrives. That 30:2 ratio stays the same whether one or two people are performing CPR on an adult.
When the Chest Doesn’t Rise
If you blow and the chest doesn’t move, the airway probably isn’t open enough. Re-tilt the head, re-lift the chin, and try again. A common mistake is not tilting the head back far enough, which leaves the tongue partially blocking the throat. If you still can’t get air in after repositioning, something may be physically obstructing the airway, and you should move straight to chest compressions, which can help dislodge an obstruction.
Avoiding Air in the Stomach
One of the biggest risks of mouth-to-mouth is pushing air into the stomach instead of the lungs. This causes gastric inflation, which can lead to vomiting and make the situation much worse. The key factor is breath duration. Research modeling gastric inflation found that breaths lasting exactly about 1 second cause the least amount of air to enter the stomach. Breaths shorter than 1 second force you to blow harder, creating pressure that overcomes the valve at the top of the stomach. Breaths longer than 1 second keep that pressure applied for too long, with the same result. A steady, moderate, 1-second breath is the sweet spot.
Blowing too forcefully is the other main culprit. You don’t need a deep, full breath. Just blow enough to see the chest rise. Think of a normal, relaxed exhale rather than blowing up a balloon.
Technique for Infants and Children
For babies under 1 year old, the technique changes in several important ways. Instead of tilting the head back, keep it in a neutral position or only very slightly tilted. An infant’s airway is tiny, and over-tilting can actually kink it shut. Cover both the baby’s mouth and nose with your mouth to create a seal. Give 2 gentle puffs of air, each lasting 1 second. You’re using only a small amount of air from your cheeks, not a full breath from your lungs. Watch for the chest to rise just slightly. Compress the chest with 2 fingers on the breastbone at a depth of about 1.5 inches.
For children between age 1 and puberty, use the same head-tilt, chin-lift technique as adults, but with less force. Pinch the nose, seal your mouth over theirs, and give 1-second breaths watching for chest rise. Use 1 or 2 hands for compressions at a depth of about 2 inches. The compression-to-breath ratio is 30:2 for a single rescuer, but drops to 15:2 when two rescuers are working together, which is different from adult CPR.
When Mouth-to-Nose Is the Better Option
Sometimes mouth-to-mouth isn’t physically possible. If the person has a jaw injury, severe facial trauma, or you simply can’t get a seal around their mouth, the American Heart Association recommends mouth-to-nose ventilation as an acceptable alternative. Close the person’s mouth with your hand, seal your lips around their nose, and blow for 1 second just as you would with mouth-to-mouth. The same rules apply: watch for chest rise, give 1-second breaths, and avoid blowing too hard.
Drowning and Opioid Overdose
For most cardiac arrests in adults, hands-only CPR (compressions without breaths) is the current recommendation for untrained bystanders. But there are situations where rescue breaths are essential. Drowning is the most important one. Because drowning is fundamentally a breathing problem rather than a heart problem, the lungs need air before compressions will do much good. The protocol for a drowning victim starts with 5 initial rescue breaths before beginning the 30:2 compression-to-breath cycle. Some drowning victims who still have a heartbeat but aren’t breathing normally will respond after just a few rescue breaths alone.
Opioid overdose is another scenario where breathing stops before the heart does. The person’s brain stops sending signals to breathe, but their heart may still be beating. Rescue breathing can keep them alive until naloxone is administered or paramedics arrive.
Using a Barrier Device
If you have access to a CPR pocket mask or face shield, use it. These barrier devices sit between your mouth and the person’s face, reducing direct contact with saliva and other fluids. A pocket mask is a rigid, clear plastic mask with a one-way valve that directs your breath into the person while preventing backflow. A face shield is a simpler, flat sheet with a filter or valve in the center. Both work for delivering effective breaths.
The actual risk of catching a disease through mouth-to-mouth is extremely low, even without a barrier. The risk of contracting HIV from saliva during resuscitation, for instance, is considered negligible when standard procedures are followed. Still, barrier devices are inexpensive, fit in a glove box or first-aid kit, and remove the hesitation many people feel about putting their mouth on a stranger’s.
Putting It All Together
The full sequence, assuming you’ve confirmed the person is unresponsive and called emergency services: tilt the head back, lift the chin, pinch the nose, seal your mouth over theirs, blow for 1 second, watch for chest rise, let the air escape, and repeat. If there’s no pulse, alternate 30 chest compressions with 2 breaths. If there is a pulse but no breathing, give 1 breath every 6 seconds. For infants, cover both the mouth and nose and use gentle puffs instead of full breaths. For drowning victims, start with 5 rescue breaths before compressions.
Reading these steps is useful, but practicing on a mannequin is what makes them stick under pressure. Community CPR courses, often free or low-cost through the Red Cross or local fire departments, let you rehearse the head tilt, the seal, and the breath volume until the sequence becomes automatic.