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Excessive thirst is an abnormal feeling of always needing to drink fluids.

Increased thirst; Polydipsia; Excessive thirst

Drinking lots of water is usually healthy. However, the urge to drink too much may be the result of a physical or emotional disease. Excessive thirst may be a symptom of high blood sugar (hyperglycemia). It can be an important clue in detecting diabetes.

Excessive thirst is a fairly common symptom. It is often the reaction to fluid loss during exercise, or to eating salty foods.

• A recent salty or spicy meal
• Bleeding enough to cause a significant decrease in blood volume
• Diabetes
• Diabetes insipidus
• Drugs such as anticholinergics, demeclocycline, diuretics, phenothiazines
• Excessive loss of water and salt (possibly due to not drinking enough water, profuse sweating, diarrhea, or vomiting)
• Loss of body fluids from the bloodstream into the tissues due to:
  • Conditions such as severe infections (sepsis) or burns
  • Heart, liver, or kidney failure
• Psychogenic polydipsia, the result of a mental disorder

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

A very strong, constant urge to drink may be a sign of a psychological problem, which may mean psychological help is needed.

For thirst caused by diabetes, follow the prescribed treatment 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 get 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?
• Are you eating more salty or spicy foods?
• How much salt do you have each day?
• Did you change 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 happening at the same time?
• Have you recently suffered a burn or other injury?
• Are you urinating more or less frequently than usual?
• Are you producing more or less urine than usual?
• Have you noticed any bleeding?
• Are you sweating more than usual?
• Is there any swelling in your body?
• Do you have a fever?

A psychological evaluation may be recommended if the health care provider suspects a psychological compulsive thirst. Your fluid intake and output will be closely watched.

Diagnostic tests that may be performed include the following:

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

Robinson AG, Verbalis JG. Posterior pituitary. In: Kronenberg HM, Shlomo M, Polonsky KS, Larsen PR, eds. Williams Textbook of Endocrinology. 11th ed. Philadelphia, Pa:Saunders Elsevier; 2008:chap 9.

Oh MS. Evaluation of renal function, water, electrolytes, and acid-base balance. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 21st ed. Philadelphia, Pa: Saunders Elsevier;2006:chap 14.