Background: Previously published investigations suggest a positive effect of increased water intake on headache, but a randomised controlled trial has not been done.
Objective: To investigate the effects of increased water intake on headache.
Methods: Randomised controlled trial in primary care with two groups and a follow-up period of 3 months. Patients were included if they had at least two episodes of moderately intense headache or at least five mildly intense episodes per month and a total fluid intake of less than 2.5 l/day. Both groups received written instructions about stress reduction and sleep improvement strategies. The intervention group additionally received the instruction to increase the daily water intake by 1.5 l. The main outcome measures were Migraine-Specific Quality of Life (MSQOL) and days with at least moderate headache per month.
Results: We randomised 50 patients to the control group and 52 patients to the intervention group. Drinking more water resulted in a statistically significant improvement of 4.5 (confidence interval: 1.3-7.8) points on MSQOL. In addition, 47% in the water group reported much improvement (6 or higher on a 10-point scale) on perceived intervention effect against 25% in the control group. However, drinking more water did not result in relevant changes in days with at least moderate headache.
Conclusions: Considering the observed positive subjective effects, it seems reasonable to recommend headache patients to try this non-invasive intervention for a short period of time to see whether they experience improvement.