What should you know about blood pressure medicine hydrochlorothiazide?

This medicine is a thiazide diuretic, sometimes called a water tablet. The extra urine may be more noticeable after a dose, so many people take it earlier in the day. It can be prescribed alone or alongside another blood pressure medicine. Your clinician may check blood pressure and blood tests because treatment can alter salts such as sodium or potassium and affect kidney function.

Take it exactly as prescribed and keep a routine that makes the dose easy to remember. Do not double a missed dose; ask a pharmacist or clinician what to do if you are unsure. Rise slowly if you feel light-headed, drink sensibly in hot weather, and tell your care team about kidney disease, gout, diabetes, pregnancy or other medicines. Do not stop it without advice, even if your readings improve.

Seek urgent help for fainting, severe weakness, confusion, chest pain, severe breathlessness, a new facial droop, or trouble speaking. Contact a clinician promptly for persistent vomiting or diarrhoea, marked thirst, muscle cramps, an irregular heartbeat, or a rash with swelling. These symptoms can signal dehydration, an electrolyte problem, an allergic reaction or another condition needing assessment.

Ask when to take your dose, whether you need blood tests, how to handle illness or hot weather, and which painkillers or supplements may interact with it.