This week i kicked soda, and 3 out of the 4 cups of coffee a day I have. I'm a full blown addict. But now im drinking LOTS of water, and I have one mug of black coffee before the gym in the morning. The headaches lasted about 3 1/2-4 days....but honestly, im already feeling a million times better, i think the water flushed alot out. Hang in there...caffeine is great, but this refreshed feeling is actually better. Not to mention its helped with my anxiety. Good luck