The caffeine content of a cup of coffee varies enormously, but a typical 150 ml cup of instant coffee provides about 65 mg of caffeine. A chronic intake of large doses of caffeine can lead
to the physical dependence, tolerance and many side effects.
Caffeine has a vasoconstricting effect on the brain and a vasodilating effect on peripheral blood flow. This property explains the presence of caffeine in several medications for migraine headaches.
Caffeine produces analgesic effects on the central nervous system and enhances motoneuronal excitability, facilitating motor unit recruitment.
Caffeine has been used for a long time as an adjuvant to analgesic preparations containing aspirin, phenacetin, paracetamol, and salicyla- mide.
Coffee and analgesic effects
