Drinking lots of water is usually healthy. However, the urge to drink excessively beyond a certain limit may reflect an underlying disease, either physical or emotional. Excessive thirst may be a symptom of high blood sugar (hyperglycemia) and can be an important clue in detecting diabetes.

Excessive thirst is a fairly common symptom and is often the reaction to fluid loss during exercise or intake of salty foods.

• A recent salty or spicy meal
• Eexcessive loss of water and salt (as with water deprivation, profuse sweating, diarrhea, or vomiting)
• Diabetes mellitus
• Diabetes insipidus
• Drugs such as anticholinergics, demeclocycline, diuretics, phenothiazines
• Bleeding enough to cause a significant decrease in blood volume
• Loss of body fluids from the bloodstream to the tissues
  • Can occur with conditions such as severe infections (sepsis) and with burns
  • Heart, liver, or kidney failure
• Psychogenic polydipsia

Because thirst is usually the body's way of replacing water loss, it is usually advisable to drink plenty of liquids.

For compulsive thirst, seek psychological help.

For thirst caused by diabetes, follow prescribed therapy to properly control blood sugar levels.

• Excessive thirst is persistent and unexplained.
• Thirst is accompanied by other unexplained symptoms such as blurry vision and fatigue.
• You are passing more than 5 quarts of urine per day.

The health care provider will obtain your medical history and will perform a physical examination.

Medical history questions documenting excessive thirst in detail may include the following:

• Time pattern
  • How long have you been aware of having increased thirst?
  • Is it consistent during the day?
  • Is it worse during the day?
  • Did it develop suddenly or slowly?
• Eating habits
  • Has your intake of salty or spicy foods increased?
  • How much salt do you consume each day?
  • Have you changed your diet?
  • Have you noticed an increased appetite?
  • Have you noticed an unintentional weight gain?
  • Have you noticed an unintentional weight loss?
• Other
  • Has your activity level recently increased?
  • What other symptoms are occurring at the same time?
  • Has there been a recent burn or other injury?
  • Have you noticed an increased or decreased frequency of urination?
  • Have you noticed an increased or decreased amount of urine produced?
  • Have you noticed bleeding?
  • Have you noticed excessive sweating?
  • Is there swelling?
  • Is there a fever?

A psychological evaluation may be recommended if compulsive thirst (of psychologic origin) is suspected. Fluid intake and output will be closely monitored.

Diagnostic tests that may be performed include the following:

• Urinalysis
• CBC and blood differential
• Serum calcium
• Blood glucose level
• Urine osmolality
• Serum osmolality