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Caffeine has a paradoxical relationship to migraine headaches. While it can be found in conjunction with such common over-the-counter painkillers as acetaminophen and aspirin, it is also implicated as a migraine trigger. Many migraineurs, myself included, have found that caffeine alone can significantly reduce the pain of a migraine headache, especially when consumed prior to the onset of the headache. Yet caffeine, which is seen as one of the more potent migraine remedies, is reported to have a long-term effect as a trigger. In fact, as you’ll find out in this article, caffeine may even be one of the foremost migraine causes. This paradoxical relationship between the world’s favorite stimulant and your cranial woes deserves, in my view, special attention.

When taken in doses which are likely to be consumed by human beings (e.g. somewhere between a cup of coffee and three pots), caffeine’s one and only known effect on the human body is to block adenosine receptors, preventing the adenosine from attaching to these receptors. Adenosine, a robust neurotransmitter, happens to have a great number of functions; however, one of its primary function is to regulate the production of other neurotransmitters such as dopamine, serotonin, norepinephrine and acetylcholine. In case you haven’t heard, these neurotransmitters happen to be your body’s primary means of handling and eliminating the sensation of pain. Even more notable is the fact that adenosine alone is know to kill pain in certain areas, such as the brain stem, and cause pain in other areas, such as the skin and eyes.

The prevailing folk wisdom is that migraines are caused by either dilation of blood vessels or oscillation of blood vessels. However, it is important to note that this dilation and oscillation is, itself, caused by something else. Incidentally, adenosine’s effect on the blood vessels is dilatory; whereas, caffeine’s effect on the blood vessels is contractive. So even if we follow folk wisdom, there is already a distinct relationship between caffeine, adenosine, and your migraine headaches: if migraines are associated with blood vessel dilation, and adenosine dilates blood vessels, then it stands to reason that adenosine somehow contributes to the pain associated with migraines. It also stands to reason that caffeine, which counteracts adenosine and contracts blood vessels, would help alleviate this pain.

Interestingly enough, migraine headaches have been determined to be associated with increased levels of adenosine in both the head and the neck area. Because caffeine is known to be an effective migraine headache treatment, and because caffeine’s only known chemical effect is to block adenosine receptors, one would naturally be led to believe that somehow these increased levels of adenosine during a migraine have a central role in the sensation of pain. So, while adenosine seems to be a painkiller in some parts of the body, where migraineurs are concerned, it is apparently a pain-causer. Thus, the blocking effect of caffeine becomes a fairly obvious means of reducing the pain that so famously accompanies migraine headaches.

So far so good, right? If you get a headache, just drink some coffee and watch the headache dissolve. Case closed, next please!

Not so fast, buddy.

Unfortunately, because caffeine is a neurotoxin, your body will naturally attempt to adapt to its presence. So although the action of caffeine is to block the reception of adenosine, your body will compensate by becoming more sensitive to adenosine. In other words, you will develop more adenosine receptors and these receptors will become more sensitive. This leads to the famous adverse reaction to using caffeine as a long-term migraine headache treatment. Your body begins to expect the regular dose of caffeine and, if it doesn’t get it, will find itself flooded with the adenosine that it expects to be blocked by the caffeine. So our potential cure can apparently make the problem much worse by transforming itself from one of your migraine remedies into one of your migraine causes.

This double-edged sword aspect of caffeine suggests that a migraineur would be best served by taking an approach of moderation: caffeine can help relieve pain, but taken in excess it contributes more pain than it alleviates. However, even taking caffeine in moderation leads to an undesirable neural adaptation: increased sensitivity to adenosine, decreased sensitivity to dopamine, serotonin and other neurotransmitters whose action is similar to caffeine and contrary to adenosine. It turns out that a single cup of coffee a day (100mg) will trigger your body’s adaptive response to caffeine: more pain-causing neurotransmitters and fewer painkilling neurotransmitters. Furthermore, long-term and/or heavy caffeine users who quit caffeine report an extreme sensitivity to caffeine as a migraine trigger. In other words, for some people, the threshold for your body’s adaptation (read: addiction) to caffeine can be much lower than 100mg per day.

So what’s the ultimate cost of being both a migraineur and a caffeine user? Well, studies are inconclusive. Because all studies of the effects of caffeine on headaches have not actually tested their control groups for the presence of caffeine in their diets and because these studies have relied on the test subjects to report their own diets, it is highly likely that in our caffeine steeped society, the control group didn’t control very much.

Nevertheless, the chemistry is clear: high levels of adenosine are present during migraine headaches; adenosine causes blood vessel dilation, which is a condition directly associated with migraine headaches and was once thought to cause them; caffeine encourages greater production of and receptivity toward adenosine. there is no question that caffeine produces conditions in the body which are highly conducive of migraine headaches. So if you want to do everything in your power to quash the migraines, it would be prudent to cut the drug out of your diet entirely. But do it slowly! Everyone knows that caffeine withdrawal feels exactly like migraines.