When we have a headache, someone is bound to suggest drinking water and taking deep breaths. There are no reasons not to, but no scientific basis either, warned Dr Pablo Irimia. "Oxygen doesn't play a fundamental role in this case, In fact, in cases of severe migraine oxygen is never administered. Obviously, breathing deeply is a relaxation mechanism and that always helps," he said. With regard to water, "Dehydration can lead to migraines, but that doesn't mean that drinking water helps to ease them. In fact, as sufferers often feel nauseous when they have a migraine, it is not advisable to take in much liquid," he explained.