Chronic dehydration can be mild or severe. Certain groups, such as older adults and athletes, may be more at risk.

Dehydration can occur when a person loses excessive water and does not take enough in to replace it. Causes include acute vomiting and diarrhea, heat exposure, prolonged vigorous exercise, and some conditions and medications.

Chronic dehydration occurs over a longer period of time. It can be mild or, in serious cases, lead to complications.

This article looks at chronic dehydration, including its signs and symptoms, effects, causes, treatments, and prevention.

a man with a headache due to chronic dehydrationShare on Pinterest
A person with chronic dehydration may experience headaches and be unable to focus or concentrate.

How much water a person needs each day is difficult to assess and can vary from person to person. A person’s water needs are based on their metabolism, environmental conditions, and activity levels.

The Third National Health and Nutrition Examination Survey based its adequate intake for total water intake on a combination of drinking water, beverages, and food.

For males aged 19–30 years, it recommends 3.7 liters (l) per day. For females aged 19–30 years, it recommends 2.7 l per day.

However, there is no scientific or clinical consensus for precise values of daily water requirements, according to one 2012 review.

Someone can become dehydrated if they lose as little as 3% of their body weight from lack of water intake.

The signs and symptoms of dehydration depend on how dehydrated a person is. Thirst is one of the first symptoms to indicate that the person needs to drink.

Some other signs and symptoms of chronic dehydration include:

  • headaches
  • being unable to focus or concentrate
  • passing darker urine than usual
  • tiredness or fatigue
  • muscle weakness and cramps
  • constipation
  • dry, flaky skin
  • altered kidney, heart, or digestive function

The effects will depend on how severe the dehydration is. Low daily water intake can cause constipation, lack of focus, and tiredness. These symptoms can negatively impact a person’s daily life.

One 2012 review reports that the only condition consistently linked with chronic low daily water intake is urolithiasis, which occurs when stones form in the kidney, bladder, or urinary tract.

Some research has suggested that increasing water intake may help with weight management. However, there is not enough evidence to explain how this happens.

The 2012 review also cites some evidence to suggest that increased fluid intake is linked with a lower risk of some cancers, though this evidence is inconclusive.

Hydration status changes daily. The review also points out the difficulties of tracking a person’s hydration status over time and linking this with medical conditions. For this reason, it is difficult to understand the true effects of chronic dehydration on health — especially in conditions that take years to develop, such as cancers.

Chronic dehydration occurs when a person consistently loses more water than they are taking in over a long period of time. Some causes of chronic dehydration include:

  • not drinking enough fluids
  • following a diet low in foods with a high water content, such as fruits and vegetables
  • exercise and sweating
  • excessive heat
  • prolonged vomiting or diarrhea
  • taking diuretic medications
  • certain underlying health conditions

Doctors can diagnose dehydration by carrying out a physical exam, conducting a blood test, or analyzing the person’s urine.

They may prescribe electrolyte medication for people who have lost fluid as a result of diarrhea or vomiting. If a person has serious dehydration, they may need to visit the hospital to receive intravenous fluids.

In an otherwise healthy person, drinking water throughout the day and when thirsty usually keeps hydration levels up.

Exercise and heat can affect how much fluid a person needs. During athletic events, a person may lose 6–10% of their body weight in sweat. This can lead to dehydration if they do not replace these fluids.

However, larger sweat loss can be difficult to replace in the short term. A person losing a large amount of sweat through heat or exercise needs a longer recovery period, taking fluids and foods as necessary and replacing electrolytes.

Electrolytes — including sodium, potassium, magnesium, and calcium — are essential minerals for normal bodily functioning and are important in hydration. After exercise, a person can replenish their electrolyte levels with a shop-bought drink or using a homemade electrolyte recipe.

People can ensure that they are drinking enough by using various apps that monitor water intake. This might remind a person to drink, particularly if they are busy, do not often feel thirsty, or are very active.

Drinking a lot of caffeine or alcohol may also cause dehydration, especially when combined with other factors, such as heat or exercise.

Older adults are more likely to experience dehydration. This is because people often feel less thirsty as they get older, and the body begins to store less water.

One review suggests that older adults should drink water even when they are not thirsty, and that they should moderately increase their salt intake when they sweat.

Chronic dehydration can occur when a person loses more water than they take in. This can be due to various lifestyle factors, illnesses, or underlying health conditions.

If a person has any signs or symptoms of dehydration, they should see their doctor, who can advise on how to rehydrate gradually. Drinking too much water, especially in a short period of time, can be dangerous or even fatal.

Rehydrating during and after exercise can prevent dehydration. Consuming electrolyte drinks can help a person rehydrate when they are exercising or have stomach flu.

Apps that monitor water intake can be useful for people who might need reminders to drink. Adopting a healthful diet that includes plenty of fruits and vegetables can also contribute to fluid intake.