The following excerpt is from the NHS website:
Dehydration can be mild, moderate or severe, depending on how much of your body weight is lost through fluids.
Thirst is the first sign of dehydration. Other symptoms may include:
- dizziness or light-headedness
- dry mouth, lips and eyes
- dark coloured urine
- passing small amounts of urine infrequently (less than three or four times a day)
Dehydration can also lead to a loss of strength and stamina. It’s the main cause of heat exhaustion.
You should be able to reverse dehydration at this stage by drinking more fluids, without medical attention.
If dehydration is ongoing (chronic), it can affect your kidney function and cause kidney stones to develop. It can also lead to:
- liver, joint and muscle damage
- cholesterol problems