longed daily caffeine ingestion (Criterion B) . The caffeine withdrawal syndrome is indi-
cated by three or more of the following (Criterion B): headache; marked fatigue or
drowsiness; dysphoric mood, depressed mood, or irritability; difficulty concentrating;
and flu-like symptoms (nausea, vomiting, or muscle pain/stiffness). The withdrawal syn-
drome causes clinical significant distress or impairment in social, occupational, or other
important areas of functioning (Criterion C) . The symptoms must not be associated with
the physiological effects of another medical co ndition and are not better explained by an-
other mental disorder (Criterion D). 
Headache is the hallmark feature of caffeine withdrawal and may be diffuse, gradual
in development, throbbing, severe, and sensitive to move ment. However, other symptoms
of caffeine withdrawal can occur in the abse nce of headache. Caffeine is the most widely
used behaviorally active drug in the world and is present in many different types of bev-
erages (e.g., coffee, tea, maté, soft drinks, energy drinks), foods, energy aids, medications,
and dietary supplements. Because caffeine ingestion is often integrated into social customs
and daily rituals (e.g., coffee break, tea time ), some caffeine consumers may be unaware of
their physical dependence on caffeine. Thus, caffeine withdrawal symptoms could be un-
expected and misattributed to other causes (e.g ., the flu, migraine). Furthermore, caffeine
withdrawal symptoms may occur when indivi duals are required to abstain from foods
and beverages prior to medical procedures or  when a usual caffeine dose is missed be-
cause of a change in routine (e.g., during travel, weekends).