What Causes Excessive Thirst?

Conditions list medically reviewed by George Krucik, MD, MBA

It’s normal to feel thirsty after eating spicy foods or performing strenuous exercise, especially when it’s hot. But sometimes your thirst is stronger than usual and continues after you drink. You may even experience blurred vision and fatigue.... Read More

It’s normal to feel thirsty after eating spicy foods or performing strenuous exercise, especially when it’s hot. But sometimes your thirst is stronger than usual and continues after you drink. You may even experience blurred vision and fatigue. These are symptoms of excessive thirst, which may signal a serious underlying medical condition.

Causes of excessive thirst

Causes may include:

  • eating salty or spicy foods
  • illness
  • strenuous exercise
  • diarrhea
  • vomiting
  • burns
  • significant loss of blood
  • certain prescription medications, including lithium, diuretics, and certain antipsychotics

Frequent excessive thirst or thirst that can’t be quenched can be symptoms of serious medical conditions, such as:

  • Dehydration: This occurs when you lack the proper amount of fluids for your body to function properly. Severe dehydration is life-threatening, especially for infants and young children. Dehydration can be caused by illness, profuse sweating, too much urine output, vomiting, or diarrhea.
  • Diabetes mellitus: Excessive thirst can be caused by high blood sugar (hyperglycemia). It’s often one of the first noticeable symptoms of this type of diabetes.
  • Diabetes insipidus: This form of diabetes occurs when your body can’t regulate fluids properly. This causes an imbalance of water in your body, leading to excessive urination and thirst.
  • Dipsogenic diabetes insipidus: This condition is caused by a defect in the thirst mechanism, resulting in increased thirst and liquid intake.
  • Heart, liver, or kidney failure
  • Sepsis: This is a dangerous illness caused by a severe inflammatory reaction from infection with bacteria or other germs.

When to seek medical attention

Thirst is your body’s way of telling you that it’s low on fluids. In normal circumstances, you should be able to quench your thirst fairly quickly. However, if your urge to drink remains constant, or does not go away after you drink, it may be a sign of a serious health problem, especially if combined with other symptoms. This constant urge to drink could also be a psychological problem.

You should consult with your doctor if:

  • thirst is persistent, regardless of how much you drink
  • you also have blurry vision, excessive hunger, or cuts or sores that do not heal
  • you are also fatigued
  • you are urinating more than five quarts a day

Diagnosing excessive thirst

To help diagnose the reason for your excessive, unresolved thirst, your doctor will ask you for a complete medical history, including any previously diagnosed conditions. Be prepared to list all of your prescription and over-the-counter medications and supplements.

Some questions your doctor may ask include:

  • How long have you been aware of your symptoms?
  • Are you also urinating more than usual?
  • Did your symptoms begin slowly or suddenly?
  • Does your thirst increase or decrease during certain times of the day?
  • Have you made dietary or other lifestyle changes?
  • Has your appetite for food been affected?
  • Have you gained or lost weight?
  • Have you recently had an injury or burn?
  • Are you experiencing any bleeding or swelling?
  • Have you had a fever?
  • Have you been perspiring heavily?

In addition to a physical exam, your doctor may order blood and urine tests to help provide a diagnosis. These tests may include:

  • blood glucose test
  • blood count and blood differential tests
  • urinalysis, urine osmolality, and urine electrolyte tests
  • serum electrolyte and serum osmolality tests

Depending on the test results, your doctor may refer you to a specialist.

Treating excessive thirst

Treatment and outlook will depend on the diagnosis.

Risks of excessive thirst: Overhydration

When you try to quench excessive thirst, it’s possible to drink too much fluid. Taking in more water than you expel is called overhydration. This can occur when you drink too much liquid to compensate for fluid loss. It can also occur if you have disorders in the kidney, liver, or heart.

Overhydration can cause a severely low blood sodium level that could result in confusion and seizures, especially if it develops quickly.

How much fluid do you normally need?

To remain healthy, you need to drink fluid regularly throughout the day. You can increase your water intake by eating water-rich foods, such as:

  • celery
  • watermelon
  • tomatoes
  • oranges
  • melons

A good way to know if you’re getting enough fluids is to check your urine. If it’s light in color, high in volume, and does not have a heavy smell, you are probably getting enough fluid.

Every organ, tissue, and cell in your body needs water. Water helps your body to:

  • maintain a normal temperature
  • lubricate and cushion your joints
  • protect the spinal cord
  • rid your body of waste through perspiration, urination, and bowel movements

You need to take in extra fluids when you:

  • are outdoors in hot weather
  • are engaging in a rigorous activity
  • have diarrhea
  • are vomiting
  • have a fever

If you fail to replenish the fluids you lose and fail to respond to your thirst by drinking fluids, you can become dehydrated.


25 possible conditions

This feature is for informational purposes only and should not be used to diagnose. Please consult a healthcare professional if you have health concerns.

Conditions list medically reviewed by George Krucik, MD, MBA