That's because it's not simply about nicotine. It's about how hard the nicotine hits your brain because you inhale it. Think about coca farmers who suck on coca leaves throughout the day. They get mild stimulation that's not dissimilar to drinking a cup of coffee, and can take it or leave it. Compare that to smoking crack. Why is crack so much more addictive than sucking on a coca leaf? One is inhaled, one is absorbed through the skin. Nicotine patches and other NRT are absorbed, slowly, in measured doses, through the skin, and do not create what is called the "bolus effect." It's because of that bolus of nicotine hitting our brains fast and hard that we get so immensely dependent on nicotine, which mimics an important neurotransmitter called acetylcholine. Our brains actually have to grow millions of new receptor sites when we first get physically dependent on the drug, in order to handle the hard, fast hits of the acetylcholine mimic. It's a good thing, too, or we would have died of nicotine poisoning.
We never lose those millions of extra receptor sites. They are a permanent brain change. After about a year of zero inhaled hits of nicotine, the sites have gone dormant. Take heart though, the most dramatic changes happen toward the beginning of a quit!
One hit off a cigarette, cigar, nicotine-loaded vaporizer, or any other device we can dream up to deliver inhaled hits of nicotine will flood these receptor sites again and activate them, setting off the craving and withdrawal cycle all over again. It doesn't matter whether you've been 50 minutes or 50 years clean, if your brain is flooded, it has to respond. Look at what happens to the brain after just one inhaled hit off a cigarette:
The blue areas show where a tracer has been replaced by nicotine. More on these scans here: http://www.drugabuse...garette-craving
NRT works by providing a low level of nicotine in the body to help with withdrawal symptoms. As I said above, it does not create the bolus effect in the brain and does not flood the receptor sites with hard, fast hits of the drug. It's like sucking on a coca leaf to help you deal with withdrawal symptoms from smoking crack. You will still be going through major withdrawal on NRT, it just isn't the 100% withdrawal of cold turkey. Also, your receptor sites will be heading toward dormancy as long as you do not inhale even one hit of nicotine.
There's some good information here about nicotine and how it works in the body, and why inhaled nicotine, especially, is so addictive: http://www.pbs.org/w...e/nicotine.html