High blood pressure not adequately controlled by telmisartan alone, or as a single tablet for someone already taking both medicines separately.

Telmisartan blocks the angiotensin II receptor, so arteries stay relaxed and the kidneys stop retaining salt and water. Hydrochlorothiazide acts on the kidney tubule to push more sodium, and the water with it, out in the urine, reducing the volume the heart has to pump. Each also offsets a weakness of the other: the diuretic activates the hormone system that telmisartan blocks, and telmisartan limits the potassium loss the diuretic causes.

Dizziness, tiredness, passing more urine, and changes in blood salts, particularly low potassium and low sodium. Gout can flare, and blood sugar and cholesterol may rise slightly.

Not for use in pregnancy. Blood tests are needed to watch kidney function and salts, especially early on. Tell your doctor about gout, diabetes, lupus, severe kidney or liver disease, or a sulfonamide allergy. Take it in the morning so the extra urine does not disturb sleep, and take care in hot weather or during vomiting or diarrhoea, when dehydration can develop quickly. It is a prescription medicine in Pakistan.