A "caffeine headache" is a headache that occurs when someone who regularly drinks or consumes caffeine stops or cuts back on caffeine suddenly. Full definition
Most of the symptoms occur in the first 7 days, and caffeine headaches often begin on Day 1. (greensmoothiegirl.com)
It's not restoring me to normalcy because I wake up mostly normal, able to start my day without the raging caffeine headache that used to make me mutter «coffee» into my pillow until my husband brought me a cup. (bonappetit.com)
After a 13 - year caffeine headache, the Turkish Sultan Selim I overturned the ban. (scientificamerican.com)