Dehydration : types, causes, symptoms


In this blog, we learn about dehydration. It is common problem seen in general practice. It is simply treated with more intake of water, taking oral rehydration salts (ORS) and sometimes need to take intravenous fluid.

If not taking treatment than it may be fatal, it may cause damage to kidney and liver, it may cause coma, convusion and death. So, this is important topic to understand as general knowledge also.

We learn this topic in below format


Dehydration is defined as excessive loss of water from the body. Body requires certain amount of fluid intake daily for normal functions.

The most active individuals need 2 to 3 litre of water intake daily. It occurs when fluid loss is more than fluid intake. It mostly occur in diarrhoea, vomiting, in physical exertion or sport activity with more sweating and less intake of fluid.



water level dehydration
water level – dehydration

Basically, dehydration is of three types as mention in chart. Our body is formed by fluids and solids. Fluid part is more than two third of the whole body. Water forms most of the fluid part of the body. For example, if person weight is 70kg than approx 40 litre is water content in that body.

Mild 5% loss increase intake of water and ORS
Moderate 10% loss immediate treatment
Severe 15% loss emergency, need to hospitalize


  1. Mild dehydration
    It occurs when fluid loss is about 5% of total body fluids.
    It is not very serious and easily treated with more water intake and taking oral rehydration salts.
  2. Moderate dehydration
    Occurs when fluid loss is about 10% of total body fluids.
    It becomes little serious and immediate treatment should give by rehydration. If we miss or delay to give treatment, than it may be fatal.
  3. Severe dehydration
    It occurs when fluid loss is about 15%.
    It is consider as emergency and immediate hospitalization needed. When fluid loss is more than 15% occurs, it becomes very severe and life threatening.



On basis of ratio between water loss and sodium loss, dehydration is divide in to three types as mention in chart.

Types of dehydration
Isotonic loss of water & sodium

– diarrhoea

Hypertonic more loss of water than sodium fever
Hypotonic more loss of sodium diuretics


  1. Isotonic 

    If there is equal loss of water and sodium, than it known as isotonic dehydration. It mostly seen in cases of diarrhoea and vomiting.

  2. Hypertonic 

    When there is more loss of water compare to sodium, than it called hypertonic dehydration. It mostly seen in case of fever.

  3. Hypotonic

    When there is more loss of sodium compare to water, than it known as hypotonic dehydration. It mostly seen in patient, who is taking diuretics medicine.



  1. Insufficient intake of water is common cause for low water level in body
  2. Doing physical work in hot environment without taking enough water eg. outdoor sport, labour work, etc.
  3. Severe diarrhoea and vomiting
  4. More urine output in kidney disease
  5. Excess loss of water through urine in disease like diabetes mellitus, diabetes insipidus and adrenal insufficiency
  6. Taking laxative or diuretics, especially for lose the weight. This is common in athletes



MILD • Dry mouth
• Increase thirst
• Decrease urine output, sweating
• Headache, dizziness
• Weakness, cramps
SEVERE • Decrease blood pressure
• Faint
• Convulsion
• Damage to brain, kidney and liver

As you can see, that very severe dehydration leads to coma, convulsion. There is also chances of damage to brain, liver or kidney. So, whenever we suffer from fluid loss by any means, we need to correct it early as possible.



  1. Mild dehydration
    Oral rehydration salts (ORS) or lemon juice is benificial. But, Simply taking more drinking water and stopping fluid loss is enough in mild dehydration.
  2. Severe dehydration
    Drinking water alone is ineffective because it can not compensate the salt loss. So, the effective treatment is only taking Oral rehydration salts (ORS) or taking intravenous fluid.


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