As far as I know, dehydration means the condition of a body from which the water has been removed. Can the same word imply that the body is thirsty?

Simply put, is "I am thirsty" the same as "I am dehydrated"?

  • 2
    You question does not seem to be about English, but logic. Jan 11, 2012 at 10:33
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    '... the condition of a body from which the water has been removed.' that may be a technical definition. However, a practical understanding of dehydration would be more like 'water content below a prescribed level for normal physiological functioning of the body'. There are several degrees of dehydration, from mild to extremely severe to fatal.
    – Kris
    Jan 11, 2012 at 10:35
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    @RegDwight: Great edit!
    – Kris
    Jan 11, 2012 at 10:36
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    @MattЭллен: 'You question' is somewhat about English. ;)
    – Kris
    Jan 11, 2012 at 10:37
  • Perhaps the misunderstanding that dehydration has several degrees leads to claims such as this? :) Jan 11, 2012 at 18:14

6 Answers 6


I am thirsty is not equivalent to I am dehydrated.

Thirst is a symptom that you've already dehydrated.

The American Heritage Science Dictionary defines dehydration as:

A condition caused by the excessive loss of water from the body, which causes a rise in blood sodium levels. Since dehydration is most often caused by excessive sweating, vomiting, or diarrhea, water loss is usually accompanied by a deficiency of electrolytes. If untreated, severe dehydration can lead to shock.

Scientifically, we don't feel thirsty when it's cold and we don't drink as much, but we are still dehydrating (respiratory fluid loss through breathing).



The word “dehydration” does NOT imply thirsty. Cause does not imply effect. Cause may lead to effect, or may not, depending on other factors.

You could be thirsty without being dehydrated in the technical sense. And you might be dehydrated without realizing it and probably not at all thirsty.


Being thirsty is, or can be, a symptom of dehydration.


Although the answers so far provide some interesting information, they're all missing 2 serious points:

1) Thirst is only an indicator of the extent to which you're missing water. Unfortunately, this indicator is not completely accurate. It's relative, for one, and it also depends on the body temperature, current activity, stress, sickness, etc.

2) There are people who never are thirsty at all. This disorder is called adipsia:

Adipsia is a disease characterized by the absence of thirst even in the presence of body water depletion or salt excess.

This means that people with adipsia, even when dehydrated, never feel thirst.

According to the above the answer to your question is no.


Logically, no, the concepts 'thirsty' and 'dehydrated' are not the same; they are closely related but independent.

  • 'thirsty' means one actively desires water.

  • 'dehydrated' means one is dry or lacking water (in the body).

When one is dehydrated one is most likely thirsty, but if one is thirsty, one isn't so likely to be in such an extreme state as to be dehydrated.

However, in colloquial usage one might be well inclined to use 'I am so thirsty', 'I am parched', 'I am dehydrated after that run' all synonymously and pragmatically to the same end: 'please give me some water'.

So, no, by definition, they are not the same, but under many circumstances, they can be both be used to achieve the same end.


No Dehydration is very much different from being thirsty.

In simple words Dehydration is a kind of a bodily disorder due to lack of sufficient water in the body. This definitely needs some medication to get back to normalcy.

Being thirsty is a general phenomenon, where a living being feels the need to drink water to keep up his oxygen levels in the stomach.

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