Answer by Alex K. Chen:
This is seriously hard to say, and depends a lot on how much you consume, what you use it for, and your basic genetic makeup.
http://lifehacker.com/5585217/wh… has some interesting information regarding tolerance/addiction. Tolerance/addiction can happen over time, but it is reversible (however, it could be unpleasant). There may be drugs in the future that may help with the unpleasantness of caffeine withdrawal (it’s possible that bupropion and modafinil could work – as both of them are often used to alleviate withdrawal symptoms from other addictive drugs)
As one starts to regularly take in caffeine, the body and mind build up a tolerance to it, so getting the same kind of boost as one’s first-ever sip takes more caffeine—this, researchers can agree on. Exactly how that tolerance develops is not so clear. Many studies have suggested that, just as with any drug addiction, the brain strives to return to its normal function while under “attack” from caffeine by up-regulating, or creating more adenosine receptors. But regular caffeine use has also been shown to decrease receptors for norepinephrine, a hormone akin to adrenaline, along with serotonin, a mood enhancer. At the same time, your body can see a 65 percent increase in receptors for GABA, a compound that does many things, including regulate muscle tone and neuron firing. Some studies have also seen changes in different adenosine receptors when caffeine becomes a regular thing.
raqibzaman 