Water = the best medicine for headache? Maybe not. But it’s pretty good.

Is water the best medicine for headache? Maybe not. But it’s pretty good.

The classic advice from experts in headache prevention is to drink regularly. Boozing every night? Well, no. They mean staying hydrated and giving your body the fluids it needs. In addition to other preventive measures, headache specialists recommend drinking about 1.5 liters throughout the day to ward off headaches and migraines. But what is the actual basis for this golden rule?

Dehydration headache?

A British neurologist called Joseph N. Blau was one of the first scientists to describe the phenomenon of water deprivation headache. His 2003 study showed that depriving the body of fluids can cause headaches. He also observed that the headache triggered in subjects by water deprivation was relieved by fluid intake. Subjects who drank half a liter of water experienced headache relief after an average of 20 minutes. Impaired concentration, dizziness, irritability and pallor were identified in addition to the dehydration-induced headache.

Water deprivation headache is not a primary headache disorder

The proposal to include 'water deprivation headache' as a separate headache type in the ICHD list of primary headache disorders was not followed. The ICHD (International Classification of Headache Disorders) is a detailed classification of all headache disorders. It was first published by the International Headache Society in 1988. It is the standard reference used by researchers and clinicians to classify headache. The ICHD gives explicit diagnostic criteria for accurate and unique identification of each headache disorder. The current edition of the International Classification of Headache Disorders (ICHD-3) does not contain water deprivation headache as a separate primary headache disorder.

Can dehydration trigger a migraine?

Experts agree that dehydration is a classic migraine trigger. Two years after his first study, Joseph N. Blau proved that dehydration can be a factor in triggering migraine attacks. More than one-third of the migraineurs he asked said that not drinking enough fluids was a personal migraine trigger. More studies followed, confirming a connection that had not been described in the medical literature before. An Iranian study published in 2020 showed that the number and duration of migraine attacks in the research subjects was inversely related to their fluid intake. Increasing fluid intake correlated with fewer symptoms.

An interesting scenario: fasting

The Muslim fasting month of Ramadan is a very interesting scenario for studies in this area. Muslims who observe the annual fasting period do not eat or drink anything at all between sunrise and sunset. Depending on season and region, daily fasting periods can last 18 hours or more. A study at a neurological clinic in Israel (2010) in a cohort of predominantly female patients (75%) produced clear findings. The number of migraine days reported by participants was three times higher during Ramadan than in the control month. The authors concluded that the increased frequency was linked to dehydration and observed that the symptoms caused major impairment of quality of life in those affected. Many studies agree that fasting without fluids inevitably causes dehydration in people who fast all day. Other typical consequences apart from headaches include sleep and mood disorders, irritability and fatigue. Given the incredible importance of keeping the brain supplied with nutrients by taking regular meals – in general, and for preventing migraine attacks in particular – it is clear that observing long periods of fasting comes with challenges of its own.

Even mild dehydration impairs cognitive processes

All these studies show that dehydration affects our bodies in many ways, apart from triggering headaches and migraine attacks. Cognitive impairment is a common consequence. Studies show that even mild dehydration impairs blood flow to the brain, with noticeable effects on cognitive processes. Dehydration is a special risk for older adults. Many old people do not drink the recommended amounts. The associated dehydration can worsen existing weakness, fatigue and confusion.

Explanatory hypotheses: what happens when the brain is dehydrated?

The pathophysiology of dehydration-induced migraine and other headache attacks is still not fully understood. It has been suggested that water deficit puts pressure on the veins in the brain (‘dural venous stretching’), provoking a headache. If this explanation is true, correcting the water deficit would normalize blood vessel volume and cure the headache. Another suggestion is that low fluid intake makes the blood ‘hypertonic’. In a hypertonic state, the substances (electrolytes, salts) in your blood are dissolved in too little water, resulting in a higher concentration than ‘intended’. Fluid shifts out of adjacent brain tissues by osmosis to get the concentration back to normal. The end result is loss of volume in the tissues of the brain, exerting traction on the meninges (the lining around the brain). The meninges and their blood vessels have pain receptors. The result is a headache.

Clear correlation between dehydration and headaches

Although the specifics of the link between dehydration, headaches and migraine attacks are not fully understood, there is clear evidence of a connection. Regular and sufficient fluid intake is a key pillar of headache and migraine prevention. Even mild dehydration has an impact on brain performance. Preventing the slightest fluid deficit is important. If remembering to drink regularly is difficult, regular phone alerts can help remind you. You can use special apps to track your water intake. The Headache Hurts app has a feature that allows you to check your drinking habits and see how water intake (or lack of it) affects your headache burden. You can also set up reminders to drink a specific amount at regular intervals throughout the day. Remember: for headache prevention, hydration is fundamental.