Oxygen Levels Rise
Carbon monoxide levels in your blood drop by half. Oxygen levels return to normal.
What happens to your body 8 hours after quitting smoking
After 8 hours without a cigarette, the carbon monoxide levels in your bloodstream drop by half. Carbon monoxide from cigarette smoke binds to hemoglobin in your red blood cells, reducing the amount of oxygen your blood can carry. As CO levels fall, your blood can carry more oxygen to your organs and muscles. You may start to notice subtle improvements in energy and alertness as your body receives proper oxygenation for the first time.
Frequently asked questions
What does carbon monoxide do to your body?
Carbon monoxide binds to hemoglobin 200 times more effectively than oxygen. When you smoke, up to 15% of your blood carries CO instead of oxygen, starving your organs of the oxygen they need to function properly.
Will I feel more energetic after 8 hours?
Some people report feeling slightly more alert and less fatigued. The improvement is subtle at this stage but real — your blood is now carrying significantly more oxygen to your brain, muscles, and organs.