I dont drink coffee or soda so I dont think im desensitized to caffeine since I dont consume any of it. I got the caffeine pills from vitamin world its 100 tablets of 200mg for like 6 dollars. The company is 4ever fit and the expiration date is 10/2014. To be perfectly honest caffeine has never really stimulated me, I actually feel kinda tired after drinking coffee and have been known to take a nap lol.