The association between primary headaches and functional gastrointestinal disorders has been confirmed by many clinical observations. In most patients during the attacks of headache, apart from various neurological and vascular symptoms, gastrointestinal disturbances occur . Functional gastrointestinal disorders, such as irritable bowel syndrome (IBS), are reported in primary headache patients in periods between the attacks as well. On the other hand 23-53% of IBS patients have frequent headaches.~Migraine typically presents relapsing episodes of symptoms including headache, nausea, vomiting, sensory hypersensitivity and mood changes that last for hours to days . Similar to migraine, IBS is characterized by recurrent abdominal pain or discomfort with altered gastrointestinal motility and visceral hypersensitivity that returns to normal between attacks . Both pain disorders lack detectable organic causes .~An emerging model of the brain-gut axis was proposed to explain migraine and IBS as a result of a genetically sensitive nervous system that develops hyperexcitability over time as a response to multiple environmental and immunological factors.~Cluster headache (CH) characterized by its distinctive circadian and circannual periodicity, implicating the role of the hypothalamus in its underlying pathophysiology. CH and IBS are featuring recurrent attacks of pain that possess relationships with circadian rhythms and potentially hypothalamic derangements.~Tension headache that's associated with pain in head described as feeling like a tight band around head, also show many similarities with IBS such causes for both are unknown, and some studies suggest a possible link that could shed light on shared genetics of both condition .
To assess the relationship between primary headaches and irritable bowel syndrome