Unfortunately your coffee habit can lead to a sore head. Chronic daytime headaches can be caused by drinking too much coffee, or other caffeinated drinks. Caffeine is present in coffee, tea, cocoa, and colas as well as cocoa-rich chocolate. These affects tend to be cumulative so the headaches strike in the afternoon as your intake rises.
One reason could be because caffeine is a diuretic and can lead to dehydration, which in turn causes headache. It acts on the renal tubules, tiny tubes inside the kidneys that filter the blood, reabsorbing some water and nutrients and excreting the remainder as urine. ‘Caffeine inhibits the reabsorption process of fluid so more is passed out through the bladder,’ explains Professor Chris Eden, a consultant urologist at the Royal Surrey County Hospital in Guildford.
Coffee lovers and people who drink lots of cola drinks may suffer caffeine withdrawal headaches if they cut back their consumption. The theory is that caffeine interferes with a key chemical messenger that widens blood vessels in the brain. The body adjusts to this effect and can’t compensate when caffeine levels suddenly fall, leading to headache.
A good rule of thumb is not to have no more than 300mg of caffeine each day – equivalent to three mugs of instant coffee or four cups of tea. Typical cola drinks contain less than 50mg of caffeine per can. If you can’t cut down, drinking water with your coffee, like the French do, can help reduce the dehydrating effects.