Nicotine is quickly metabolised by the body and quickly eliminated. Within 2 to 3 days after quitting smoking, your body will have cleansed itself of both the nicotine and the nicotine byproducts that were drenching your system. There are some variations in how quickly the liver cleans the blood, but nicotine isn't a drug that becomes part of your general bodily make-up for the long term. Unlike such contaminants as heavy metals, you aren't stuck with residual nicotine for years to come.
The Bad News
While the actual drug is flushed out of your body quickly, and the physical symptoms of withdrawal fade just as fast, the physical and emotional aspects of addiction take much longer to come under control. Many of the reactions people think of as "withdrawal" or lingering effects of nicotine in the body are actually the symptoms of a physical and emotional addiction being denied. In other words, it is no longer the nicotine causing your body to react with dizziness, irritability and cravings, it is your body and mind expecting you to feed the addiction you have chosen to give up.
How to Deal With It
There are as many ways of coping with post-quitting symptoms as there are ex-smokers. For many, the very best way of coping is to stay busy. With nicotine no longer in the system in fluctuating levels after every cigarette, the physical reactions that used to tell you to light up a new cigarette are gone, and the emotional and physically habitual ones aren't anchored to anything but your own ability to notice them. Keeping busy helps prevent you from noticing them. There are many other methods of coping, however. Some people are unable to go cold turkey and use patches or gum. Others find substitution activities: chewing gum, gnawing pencils or toothpicks or using worry beads or rosaries to keep the hands busy and the mind still.