Body dehydration symptoms: what to know

Dehydration develops when the body loses more fluid than it replaces. Heat, exercise, fever, vomiting, diarrhoea, and reduced drinking can all contribute. Thirst is not always the first sign, particularly in older adults. Urine may become darker and less frequent, while the mouth and lips feel dry. These findings are not specific: cloudy urine, abdominal pain, burning urination, or constipation may point to another problem as well as fluid shortage.

Move to a cool place and take frequent small sips of water. If vomiting or diarrhoea is involved, an oral rehydration solution can replace water and salts more appropriately than relying only on plain water. Continue gentle fluids as tolerated and choose foods with fluid when able. Avoid strenuous activity and alcohol while recovering. People with kidney, heart, or other conditions affecting fluid balance should ask a clinician how much to drink.

Get urgent medical help for confusion, fainting, severe drowsiness, inability to keep fluids down, very little or no urine, rapid breathing, or signs of heat exhaustion such as heavy sweating with weakness. Seek advice when symptoms do not improve after drinking, or when fever, persistent diarrhoea, blood in urine, flank pain, or painful urination is present. Dehydration can accompany gastroenteritis or heat exhaustion, but those conditions need their own assessment.

Ask what may be causing your fluid loss, which rehydration drink is suitable, and whether your medicines or medical history change the advice. Record how much you are drinking, how often you urinate, and whether vomiting, diarrhoea, fever, pain, or unusual urine changes occurred.