You might know the throbbing ache in your head is the result of missing your cup of coffee this morning, but perhaps you don't know exactly why the pain occurs. In fact, when those who regularly consume caffeine miss their daily dose, a headache is the most common withdrawal symptom to arise, accompanied by fatigue, irritability, difficulty concentrating and nausea. But researchers from the University of Vermont College of Medicine and Johns Hopkins School of Medicine have now determined the "why" behind the caffeine withdrawal headache as well as some of the other withdrawal symptoms.
Caffeine
An estimated 80 to 90 percent of North Americans consume caffeine products regularly, with an average daily intake of about 280 milligrams, which is equal to about one to two mugs of coffee or three to five bottles of soft drink. As little as 100 mg of caffeine per day can lead to physical dependence and withdrawal symptoms upon abstinence, although the incidence and severity of withdrawal symptoms generally increases with higher daily caffeine doses.
Withdrawal Headache
Headache is the most common caffeine withdrawal symptom, experienced by about 50 percent of individuals who abstained from caffeine for 24 hours or more. The pain is typically described as diffuse and gradual in development, and sometimes throbbing and severe. The onset of the headache, as well as other withdrawal symptoms, usually occurs 12 to 24 hours after the last intake of caffeine, with intensity peaking at about 20 to 48 hours. The duration ranges between two and seven days.
Cause of Withdrawal Headache
Adenosine is a neurotransmitter that widens blood vessels in the brain by acting on specific adenosine receptors. Caffeine can block this effect, and the body compensates, raising its sensitivity to adenosine by increasing the number and capability of adenosine receptors on the blood vessels. When you abruptly stop the consumption of caffeine, the unhindered effects of adenosine on the now greater number of available adenosine receptors causes increased widening of blood vessels and increased blood flow in the brain, resulting in a caffeine withdrawal headache.
The Study
Researchers have long suspected that this chain of events concerning adenosine and its receptors may contribute to the headache associated with caffeine withdrawal, but previous studies fell short of proving the connection. In a 2009 study published in "Psychopharmacology," researchers from the University of Vermont College of Medicine and Johns Hopkins School of Medicine examined brain electrical activity and cerebral blood flow during caffeine withdrawal. Their study involved the administration of placebo capsules and caffeine capsules to regular caffeine users in a specific sequence, and over a long enough period of time, to leave little room for doubt about the connection between caffeine effects on adenosine receptors and caffeine withdrawal headache. The investigators demonstrated that acute caffeine abstinence increased brain blood flow and produced changes in brain electrical activity, the latter of which is thought to be related to the withdrawal symptom of fatigue.
Considerations
To avoid caffeine withdrawal headaches, gradually reduce caffeine intake to help your body get used to the lower levels of caffeine and reduce the likelihood of withdrawal effects. Additional tips include substituting decaffeinated beverages, brewing tea for shorter periods of time to reduce caffeine content, and choosing herbal teas that don't contain caffeine. You should also watch for any additional sources of caffeine, such as chocolate and some over-the-counter pain relievers.
References
- "Psychopharmacology"; Caffeine Withdrawal, Acute Effects, Tolerance, and Absence of Net Beneficial Effects of Chronic Administration: Cerebral Blood Flow Velocity, Quantitative EEG, and Subjective Effects; Stacey C. Sigmon, et al.; July 2009
- Johns Hopkins Medical Center; Information About Caffeine Dependence; July 9, 2003
- "Psychopharmacology"; A Critical Review of Caffeine Withdrawal: Empirical Validation of Symptoms and Signs, Incidence, Severity, and Associated Features; Laura Juliano, et al.; October 2004
- "International Journal of Vascular Medicine"; Caffeine's Vascular Mechanisms of Action; Darío Echeverri, et al.; Aug. 25, 2010
- MayoClinic.com; Caffeine: How Much Is Too Much?; March 24, 2009
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