After You Quit Smoking - The First Two Days Your Guide to Smoking Cessation. At 20 minutes after quitting: blood pressure decreases pulse rate drops body temperature of hands and feet increases. At 8 hours: carbon monoxide level in blood drops to normal oxygen level in blood increases to normal At 24 hours: chance of a heart attack decreases At 48 hours: nerve endings start regrowing ability to smell and taste improve Congratulations! It takes courage to put down that last cigarette. Most people feel an intense combination of fear and excitement leading up to their quit date. Being afraid to quit smoking is completely normal, and is a byproduct of addiction.