[vidarh]

Caffeine withdrawal can give you much more than headaches, and withdrawal can last for at least a week, though generally at higher dosages.

Until I realised what was going on, when I was taking breaks from using 360mg very other day - so equivalent to 5-6 cups of coffee - to boost my weight lifting in periods, I had week long bouts of diarrhoea, intense headaches, shakes setting in in the evening (so severe I had to time my painkillers, or I'd have problems swallowing them because I had difficulty holding my hands steady enough to drink a glass of water), fever, and night sweats.

Caffeine can be a nasty drug to go cold turkey from if your intake has been high. Best bet is to step down gradually (not a long period - over a week or two), coupled with pre-emptively taking paracetamol/acetaminophen in the early evening.

Often, someone who gets a lot of caffeine and starts experiencing symptoms like above may be experiencing withdrawal without being aware.