You do not need a big coffee habit to get withdrawal headaches
A daily 100 mg of caffeine, about one cup of coffee, is the lowest intake shown to do it. Symptoms start 12 to 24 hours after the last dose and can run nine days.
What the study found
One cup a day is enough to produce real withdrawal symptoms
A daily 100mg of caffeine, about one cup of coffee, is the lowest intake shown to produce withdrawal. Ten validated symptoms follow: headache, fatigue, dulled alertness, irritability and low mood among them, beginning 12 to 24 hours after the last dose and running as long as nine days.
The caveat · Plenty stop and feel nothing
Those timings are population ranges, and plenty of people stop and feel nothing at all. The 100mg figure is the lowest daily intake shown to produce withdrawal, not the usual one. This is a critical review of 57 experiments and 9 surveys rather than a pooled statistical analysis, though nothing since has replaced it.