Regularly sipping water can reduce the severity of headaches and migraines, reducing the need for painkillers.
Scientists found drinking around seven glasses a day was enough to ease pain and improve the quality of life in patients who regularly suffer headaches.
Researchers from the University of Maastricht, the Netherlands, noticed in 2005 that a patient told to drink more for a bladder problem saw his migraines get better.
Lead researcher Dr. Mark Spigt and his team recruited more than 100 patients who frequently suffered from severe or mild headaches.
The team instructed them on how to ease their discomfort, including reducing stress, improving sleep and avoiding caffeine.
But half the patients were also told to drink 1.5 litres of water a day for three months, on top of their normal liquid intake.
At the end of the study, patients filled out a questionnaire called the Migraine-Specific Quality of Life index to say how they felt. The results, published in journal Family Practice, showed those drinking extra water scored far higher on the questionnaire.
The researchers said: “We suspect that some headache patients may benefit from drinking more water and it seems reasonable to recommend they try drinking more for a short period of time to see if they experience an improvement.”
Dr. Fayyaz Ahmed, of the Migraine Trust, said the benefits of drinking water could be due to the placebo effect.
But he added: “However, regular intake of water and adequately hydrating is healthy, and a lot of people feel better.”