The relationship between caffeine and headaches is somewhat confusing. A small amount of caffeine can relieve a headache, but too much may cause one. Coffee initially constricts the blood vessels, reducing the pain. But if you drink too much, the blood vessels dilate, causing more pain. Brewed coffee has much more caffeine than tea or cola.
Some medications contain caffeine.
Most people can tolerate one or two caffeinated drinks a day. However, if you decide to switch to decaffeinated beverages, do so gradually over a week's time. Researchers have suspected that lower magnesium levels in relationship to higher calcium levels may cause migraines. Keep a food diary for a month, tracking your headaches. You may be able to determine a relationship between food and headaches.