Strong thirst; strong feeling of thirst (polydipsia)

Extreme thirst - why is that?

Many people notice a strong feeling of thirst, you are constantly thirsty and have to drink something. What can that be? Thirst occurs when there is a need for water intake. In this sense, Durst regulates the fluid balance to avoid or compensate for deficits and thus prevent dehydration. Constantly strong thirst can also be a sign of serious dysfunctions and diseases, which can be recognized by other signs, which are explained in more detail below.

Polydipsia - A Brief Overview

Thirst is a normal and important feeling to regulate the water balance in the body. Certain daily fluctuations in feeling thirsty are normal and depend on the daily diet, temperature, activity, age and fitness. This can lead to strong thirst even in completely healthy people. However, if this occurs over a longer period of time, this can be a disease symptom. Here is a brief overview:

  • Signs of polydipsia: Unquenchable thirst, frequent urination, thirst persists for several days, weight loss.
  • Not causes related to illness: Alcohol consumption, salty food, heat, sweating, diuretic medication, sports activity, physical exertion.
  • Illness-related causes: Diabetes mellitus, diabetes insipidus (water urinary dysfunction), certain mental illnesses, metabolic disorders, kidney diseases, fever, vomiting, diarrhea.

Thirst regulates the body's fluid balance

In order to ensure the water content in the organism remains constant, we feel thirst when our body has lost more than 0.5 percent of its weight in water. The water balance in healthy people is influenced by the outside temperature, diet, air humidity and physical activity. Our brain constantly monitors the right level. If certain substances in the blood are too highly concentrated, the brain triggers the feeling of thirst in order to keep the water balance as good as possible.

Signs of lack of fluid

The feeling of thirst therefore warns early of the danger of internal dehydration. But especially old people and children often ignore thirst and drink too little. If no new liquid is taken up or continues to be dispensed in large quantities (e.g. due to excessive sweating, vomiting or diarrhea), typical complaints due to lack of water can occur. The lack of fluids manifests itself to a certain extent through dry mucous membranes, a dry throat, a cracked tongue with a bark-like coating and standing skin folds. Typical symptoms of a lack of fluids are:

  • Low blood pressure (hypotension),
  • Racing heart,
  • low and highly concentrated urine,
  • Fatigue,
  • Feeling weak,
  • Nausea,
  • Difficulty concentrating,
  • Clouding of consciousness,
  • Exhaustion,
  • A headache,
  • Dizziness.

Low fluid intake is unhealthy

How much water should you drink every day? First and foremost, make sure you always drink enough. By sweating, breathing and urinating, around two to three liters of water are lost during the day, which must be balanced out through food and, above all, fluid intake. General recommendations range from two to three liters a day. As a rule, it is enough to listen to your thirst and drink whenever you are thirsty. But this rule does not apply to everyone. Seniors and children often do not develop a real feeling of thirst. In addition, certain diseases such as diabetes often lead to an abnormally increased thirst.

An abnormally strong feeling of thirst as a symptom

When people develop a constant thirst, this is medically called polydipsia. This is often an accompanying symptom of a physical illness and is associated with frequent urination (polyuria) in many sufferers. The increased urination is then the cause of the loss of fluid. Polydipsia is also a key symptom of the rarely occurring diabetes insipidus (water urinary dysfunction), a hormonal disorder with impaired water reabsorption into the kidneys. The diseases that polydipsia can indicate are discussed below.

Diabetes as a cause of strong thirst

If the strong feeling of thirst goes hand in hand with an increased amount of urine (polyuria) and leads to polydipsia the other way around, diabetes mellitus should be considered. If severe thirst, polyuria and weight loss only occur in later stages in type 2 diabetes, these can be symptoms typical of type 1 diabetes, which develop in the first hours or weeks. Other signs may include cravings for sweets, nausea, weaknesses and impaired consciousness.

Abnormal thirst due to mental illness

As a result of certain mental illnesses and psychoses, those affected sometimes tend to drink a lot of fluids. This is the case, for example, with schizophrenia, behavioral disorders or anorexia in the early stages.

Urinary dysentery leads to polydipsia

The so-called antidiuretic hormone (ADH) in the pituitary gland is the focus of the rare disease diabetes insipidus (water urinary dysfunction). Usually this hormone is only used when there is a lack of fluid and thirst. ADH binds to the kidney and leads to reduced urine excretion in order to retain fluid in the body. In patients with diabetes insipidus, depending on the form, either ADH is not released in the brain (central form) or the docking points in the kidneys are disturbed (renal form). The consequences are frequent urination, severe polydipsia and rapid dehydration. Those affected have to drink a lot of fluid to maintain the water balance. It can happen that a patient has to drink over 20 liters of water every day.

Medications as a trigger for polydipsia

Certain medications can make you feel very thirsty. Above all, diuretics, laxatives, cisplatin, rifampicin, aminoglycosides, glucocorticoids and anti-epileptics such as carbamazepine come into question. The antidepressant lithium can also trigger polydipsia when taken initially.

Other causes of increased thirst

As a by-product, fever or increased alcohol consumption can cause a strong thirst. Certain metabolic disorders can also trigger polydipsia. These include, for example, hypokalaemia (potassium deficiency) or an overactive parathyroid gland. Furthermore, kidney diseases can be the cause.

When should you see a doctor?

There are many normal conditions that sometimes make you thirstier than usual. This can be the case, for example, as a result of sports, alcohol consumption, heavily salted food, sweating or high outside temperatures. As a rule, this is not a matter of concern and does not require a visit to the doctor. However, if the strong thirst lasts for several days and is almost unquenchable, if there are abnormalities such as unwanted weight loss and increased urination, a medical examination should be carried out. (jvs, vb)

Author and source information

This text corresponds to the specifications of the medical literature, medical guidelines and current studies and has been checked by medical doctors.

Graduate editor (FH) Volker Blasek


  • R. Pfäffle, R. Holl: Diabetes insipidus neurohormonalis (D. i. Centralis), guideline of the German Society for Pediatrics and Adolescent Medicine (DGKJ), (accessed August 22, 2019), AWMF
  • James L. Lewis, III: Hypernatremia, MSD Manual, (accessed Aug 22, 2019), MSD
  • Thomas Haak, Klaus-Dieter Palitzsch: Diabetology for Practice, Thieme Verlag, 1st edition, 2012

ICD codes for this disease: R63.1ICD codes are internationally valid encodings for medical diagnoses. You can find e.g. in doctor's letters or on disability certificates.

Video: Dr. Eric Westman - LCHF and Diabetes: Theory and Clinical Experience (January 2022).