Thirst

A constant desire to drink and often associated with oropharyngeal dryness (xerostomia), mediated by hypothalamic osmoreceptors and volume/pressure receptors responding to increased plasma osmolality or decreased effective circulating volume. Possible causes are dehydration, hemorrhage, salty foods, diuretics, medical conditions (diabetes mellitus, diabetes insipidus, organ failure, hypercalcemia, pregnancy), anticholinergic medications (antihistamine, antipsychotic), and psychogenic polydipsia.