How much caffeine is too much varies from person to person. It's possible to develop tolerance to caffeine. Calling It Quits Cutting down on caffeine may be more difficult than it sounds. When someone who is dependent on caffeine stops taking it, he or she will probably experience withdrawal symptoms within 12 to 24 hours. The most common withdrawal symptom is a headache.
Symptoms can also include drowsiness, difficulty working, irritability and even flu-like symptoms.
Don't be discouraged. If you try to cut down, do so gradually instead of abruptly. You are much less likely to experience withdrawal symptoms. If you're a heavy coffee drinker, you can start cutting down by mixing decaffeinated coffee in with your regular coffee. Then after a week switch to drinking half decaf and half regular.