Scientists reviewed the existing literature that links caffeine and headaches and summarized the possible mechanisms of caffeine’s effect on migraine and other headaches. This review is available in Nutrients.
Caffeine and headaches
Caffeine is a naturally occurring methylxanthine that is predominantly present in coffee. It is also present in tea, energy drinks, and chocolate. Caffeine could be the most commonly consumed psychoactive compound worldwide.
Consumption of caffeine both occasionally and regularly has a significant effect on the nervous system. Although several studies have indicated that the consumption of caffeine impacts headaches, the underlying mechanism behind this effect is not fully understood.
Interestingly, caffeine has a dual role. It can both induce and remediate headaches. For example, it triggers headaches associated with migraine but alleviates hypnic headaches, spontaneous intracranial hypotension, and post-dural puncture headache.
For the review, all relevant articles were obtained from various databases, such as PubMed, Google Scholar, and MEDLINE, published between 1990 and May 2023. Various types of adult human-based research articles, i.e., cross-sectional, observational, clinical trials, case studies were included in this review.
Consumption of moderate amounts of caffeine, i.e., around 200–400 mg per day, is considered to be safe for healthy, non-pregnant adults.
It has been observed that intake of 50–100 mg of caffeine increases alertness, energy, reaction accuracy, and the capacity to better focus and concentrate. Furthermore, it improves cognitive performance, mood, physical fitness, and short-term memory, and reduces fatigue.
Nevertheless, many adverse effects, such as anxiety, nervousness, tremors, insomnia, and tachycardia, have been associated with the consumption of high doses of caffeine, i.e., 400–800 mg once.
Individuals with a history of seizures or hypotension are advised not to consume excess caffeine, as it can induce adverse effects. A regular intake of high caffeine doses has also been linked to central nervous system toxicity and atrial fibrillation in high-risk patients.
Caffeine - a headache inducer
Migraine is a recurrent headache disorder that might last up to 72 hours. This headache is characterized as throbbing, unilateral, with moderate-severe intensity. A migraine headache can be aggravated by routine physical activity.
In some cases, headache is accompanied by photophobia, phonophobia, and/or nausea. Chronic migraine is associated with headaches for more than 15 days, which might sometimes persist for three months as well.
Long-term consumption of caffeine triggers a cascade of physiological processes in migraine patients, which leads to different outcomes including worsening of the headaches.
Abnormal sleep patterns and the pathophysiological role of the hypothalamus are two of the common inducers of migraine. A previous study has shown that a sleep disorder, namely, familial advanced sleep phase syndrome, which is caused due to mutations in the gene casein kinase Iδ leads to sleep problems that trigger migraines.
Since caffeine prolongs the state of wakefulness, it could trigger migraine attacks via the aforementioned mechanism. A structural similarity between caffeine and adenosine has been established, along with the fact that adenosine significantly affects the development of migraine.
Adenosine induces vasodilation and modulates endogenous calcitonin gene-related peptide (CGRP) release. Several studies have indicated the antagonization of adenosine by caffeine which could lead to the development of migraine attacks.
Although caffeine withdrawal could be beneficial in treating migraines, it could trigger another type of headache, i.e., caffeine withdrawal pain. This pain is associated with the mechanism of “rebound” cerebral vasodilation.
This pain significantly reduces after two weeks of abstinence from caffeine. A recent study has shown that diclofenac in combination with caffeine can effectively alleviate migraine attacks.
Caffeine - a therapeutic agent for headache
Hypnic headache is a recurrent headache that develops during sleep and causes awakening. This type of headache lasts between 15 minutes and 4 hours, and it typically starts in patients around 50 years of age.
The exact cause of this headache is still unknown. It has been observed that caffeine stops acute hypnic headaches. In this case, patients are asked to use caffeine prophylactically before going to bed to prevent the onset of pain.
Caffeine’s analgesic effects in humans could be linked with the central dopaminergic mechanisms, where caffeine increases the release of dopamine.
Compared to decaffeinated counterparts, the majority of patients have shown better effectiveness to the combination of caffeine with paracetamol, acetylsalicylic acid, ibuprofen, and acetaminophen in the pharmacotherapy of tension headaches.
Post-dural puncture headache occurs due to a lumbar puncture performed for diagnostic or therapeutic purposes. This type of headache develops within five days of the dural puncture.
A randomized, double-blind clinical trial reported that the introduction of caffeine (1000 mL of saline and 500 mg sodium caffeine benzoate) reduces the incidence of post-dural puncture headaches.
Caffeine can both trigger and alleviate headaches. Although an appropriate dose of caffeine can mitigate headaches due to migraine and post-dural puncture, overuse can lead to chronic forms of tension headaches and migraine attacks. In the future, more research is required to better understand the role of caffeine and its safety in medicine.