The medical term for excessive thirst

Polydipsia describes a symptom, not a diagnosis. It may follow fluid loss from sweating, vomiting or diarrhoea, or occur with dry mouth and dehydration. Frequent urination can accompany diabetes because dissolved glucose pulls water into urine. Kidney problems, salty foods, some medicines and mouth breathing may also contribute.

A clinician will distinguish true thirst from a dry mouth or a habit of sipping. They may ask about urine volume, sleep disruption, food and drink, medicines, pregnancy, weight change and other symptoms. Blood and urine checks can help identify the cause.

Note how long the symptom has lasted and whether it follows activity, heat or illness. Keep water available and drink regularly according to thirst, while avoiding large amounts in a short time. Do not stop prescribed medicines without advice. Book an appointment when thirst is persistent, unexplained or paired with frequent urination, tiredness or visual change.

Urgent assessment is appropriate for confusion, fainting, severe drowsiness, repeated vomiting, inability to drink, very little urine, fast or difficult breathing, or sudden severe weakness. These signs can reflect a serious fluid or metabolic disturbance rather than a simple dry mouth.

Is this likely to be thirst, dry mouth or both? Could a medicine, blood sugar change or fluid loss explain it? What tests are suitable? How much should I drink while waiting for review?