Polydipsia

Polydipsia is a medical term meaning abnormally large (poly-) intake of fluids by mouth. That is, drinking (-dipsia). The fluid is usually water, though some people may think of alcohol because of the etymologically-related term dipsomaniac, meaning an alcoholic.

Polydipsia is almost always associated with dehydration due to polyuria (excessive urination), if the condition is prolonged beyond a few hours in those with functioning kidneys.

It is often, and characteristically, found in diabetics, often as one of the initial symptoms, and in those who fail to take their anti-diabetic medications or whose dosages have become inadequate. It is also caused by other conditions featuring osmotic diuresis and by diabetes insipidus ("water diabetes"), and forms part of the differential diagnostic tree for them, as well.

Psychogenic polydipsia is a rare psychological disorder sometimes described in patients with mental illness or learning difficulty. If the patient is institutionalised, close monitoring by staff is necessary to control fluid intake.

Polydipsia is also a symptom of atropine or belladonna poisoning.