Excessive thirst is an abnormal feeling of constantly needing to consume fluids.

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
• Excessive loss of water and salt (possibly due to 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 due to:
  • Conditions such as severe infections (sepsis) or burns
  • Heart, liver, or kidney failure
• Psychogenic polydipsia

Because thirst is usually the body's signal to replace water loss, it is usually appropriate to drink plenty of liquids.

Compulsive thirst may indicate a psychological cause, which may mean psychological help is required.

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 perform a physical examination.

Medical history questions may include the following:

• 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?
• 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?
• 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
• Serum sodium