Tiredness and feeling thirsty all the time

Thirst may follow heat, sweating, vomiting, diarrhoea, fever or not drinking enough. Dry mouth and dark urine support dehydration, although thirst can have other causes. High blood sugar, kidney problems, medicines and a salty diet may also affect thirst and energy. Frequent urination, blurred vision, unexplained weight change, nausea or weakness add useful context. The symptom combination does not identify one diagnosis by itself.

Drink regularly and replace fluids after sweating or illness; avoid relying on alcohol or very sugary drinks to quench thirst. Keep track of how much you drink, how often you urinate, and whether symptoms follow heat, meals or exercise. Review medicines with a pharmacist or clinician rather than stopping them yourself. Arrange an appointment if thirst and tiredness continue, disturb sleep or come with frequent urination.

Seek urgent help for confusion, fainting, severe weakness, inability to keep fluids down, very little urine, deep or rapid breathing, or severe abdominal pain. Contact a clinician promptly for persistent thirst with frequent urination, blurred vision, vomiting, unexplained weight change or worsening fatigue. These features can signal fluid imbalance or a condition needing timely tests.

Ask whether you need checks for hydration, blood sugar, kidney function, anaemia or medication effects. Describe urine changes, fluid intake, recent illness, heat exposure, diet, sleep and any weight or vision changes.