Why Does Caffeine Make A Headache Better?

Whether consumed in a beverage or taken as a medication, caffeine has been used over the years to ease the symptoms of headaches. Caffeine is both a natural and synthetic substance known to exert a stimulant effect in your body's central nervous system. Studies show that at low to moderate doses, caffeine can make a headache better; however, taken in high doses, caffeine actually can cause headaches.

Caffeine

Classified as a methylxanthine, caffeine functions in your body mainly by blocking the action of adenosine. By blocking adenosine, the excitatory state of your neurons decreases, releasing certain neurotransmitters such as dopamine. While dopamine is not technically a painkiller, dopamine can give you an overall sense of well-being. In the brain stem and spinal cord, adenosine functions as a painkiller. Outside of the brain stem and spinal cord, adenosine causes pain. Your body rapidly absorbs caffeine, and caffeine can cross the blood-brain barrier and pass into your brain.

Headache

According to the University of Maryland Medical Center, a headache results in pain or discomfort to your head, scalp or neck. According to "Harrison's Principles of Internal Medicine," medical professionals in the 1940s thought that the dilation of blood vessels in the brain caused a compression of the adjacent structures, resulting in a headache. Today, medical professionals recognize that a dysfunction of the pain-sensitive features of the brain causes most headaches. Additionally, the chemical activity of your brain, the nerves or blood vessels outside your skull and the muscles of your head and neck can play a role alone or together in causing headaches.

Caffeine as a Headache Reliever

According to "Harrison's Principles of Internal Medicine," caffeine relieves headaches through several mechanisms that are not yet fully understood. Caffeine inhibits the presence of prostaglandins, compounds that cause pain and also constricts blood vessels. Caffeine also magnifies the effects of certain types of painkillers, such as aspirin. Moreover, caffeine helps to block adenosine, a nucleotide closely related to headache episodes. Although adenosine serves as a painkiller in the brain stem and spinal cord, it also can cause headaches.

Caffeine Both Causes and Relieves Headaches

A large study between 1995 and 1997 by the Norwegian University of Science and Technology found that having more than 200 mg of caffeine a day can cause headaches and irritability. Additionally, the study concluded that while large amounts of caffeine cause headaches, moderate or low amounts of caffeine can relieve headaches. The study also found that the frequency of non-migraine headaches were 18 percent higher in people with high caffeine consumption, defined as 500 mg per day or more, than in those with the lowest consumption, an average of 125 mg a day.