Green tea comes from the same plant, Camellia sinensis, as black tea, but it is cured in a different fashion. It is popular in China and Japan and increasingly in other countries as well. Green tea is often recommended as a health-promoting drink and as a natural treatment for such conditions as high cholesterol. Green tea may also be helpful in treating certain kinds of headaches including migraines. Unfortunately, green tea can also be a headache trigger.
Green Tea and Caffeine
The main active ingredient of green tea in terms of both relieving and causing headaches is caffeine. Green tea contains a moderate dose of caffeine, about 8 to 36 milligrams of caffeine per 5-ounce cup. This is significantly lower than the caffeine found in a 5-ounce cup of black tea, which contains 25 to 110 milligrams. For comparison, the same size cup of drip coffee contains 106 to 164 milligrams of caffeine.
Caffeine and Analgesics
Caffeine is often paired with analgesics, such as aspirin and acetaminophen, because its presence increases their effectiveness. According to the Cleveland Clinic, a dose of caffeine helps make pain relievers 40 percent more effective. The clinic also notes that this allows patients to take less medication per dose, reducing the risk of side effects, rebound symptoms and addiction. Caffeine also helps the body absorb medications more quickly, allowing the patient to feel relief sooner. By adding caffeine and, in turn, taking less medication, the patient reduces the risk for potential side effects and reduces the risk of habitual or addictive usage. The amount of caffeine found in a 5-ounce cup of green tea is comparable to that found in commercial over-the-counter brands of aspirin-plus-caffeine pills.
Another method by which the caffeine in green tea relieves headache pain is through vasoconstriction. Just before the onset of a migraine, blood vessels in the head begin to dilate. Caffeine, on the other hand, causes blood vessels to constrict. Thus, a cup of green tea, with its moderate caffeine dosage, can stop a headache in its tracks.
Headaches Caused by Green Tea
Although green tea can be effective in relieving headaches for some people, it may actually triggers headaches in others. Caffeine sometimes triggers migraines directly. More often, however, headaches set in due to caffeine withdrawal, when a person stops consuming caffeine after a long period of regular use. For this reason, the National Headache Foundation recommends against daily caffeine use by people with frequent headaches.