Hydrochlorothiazide Tablets

Hydrochlorothiazide is an oral thiazide diuretic that lowers blood pressure and reduces fluid build-up by helping the kidneys pass more sodium and water into the urine. We list it as a tablet for oral use in two strengths, 12.5 mg and 25 mg, so customers can match the strength and quantity to the treatment their prescriber has set.

What hydrochlorothiazide is used for

Hydrochlorothiazide is established for treating hypertension and for reducing oedema linked to conditions such as heart failure or certain kidney and liver problems. It works within one to two hours of a dose, with effects lasting around six to twelve hours, and it is often combined with other blood pressure medicines when a single agent is not enough. Because the exact hydrochlorothiazide product, strength and tablet formulation supplied under this listing has not been separately confirmed on the UK medicines register, customers should check the patient information leaflet included in the pack and, where in doubt, confirm the details with a pharmacist before starting treatment.

Essential facts

Hydrochlorothiazide belongs to the thiazide diuretic class (ATC code C03AA03). For hypertension, adult treatment commonly starts at 12.5 mg once daily in the morning, sometimes increasing to 25 mg if blood pressure control is insufficient. Adults treated for oedema may be prescribed 25-100 mg daily, sometimes as an intermittent regimen, but the schedule must be set by a clinician. Doses are usually taken with or without food, although morning dosing helps avoid disturbed sleep from increased urination. If a dose is missed, it should not be replaced with a double dose. Dosing in children is weight-based and requires close clinical supervision. Tablets should be stored at room temperature between 20°C and 25°C, protected from light and moisture.

Available strengths and pack sizes

We currently offer hydrochlorothiazide tablets in 12.5 mg and 25 mg strengths, with several pack sizes so customers can choose a quantity that fits their prescribed course.

Safety notes and ordering information

Common side effects include dizziness, low blood pressure, increased urination, and changes in blood sodium or potassium levels. Blood pressure, electrolytes and kidney function may need checking before treatment, after dose changes and periodically during longer-term use. Hydrochlorothiazide should not be used by people who cannot produce urine, while severe kidney impairment requires specialist assessment. It can increase uric acid and aggravate gout. As a sulfonamide-derived medicine, it also requires caution in anyone with a relevant sulfonamide-derived-medicine allergy, and it can affect blood glucose control in people with diabetes.

Hydrochlorothiazide is not recommended in pregnancy or while breast-feeding, and it may cause dizziness or fatigue that affects driving, particularly when treatment is first started or the dose changes. Lithium can reach harmful concentrations when taken with thiazide diuretics, NSAIDs such as ibuprofen may reduce the diuretic and blood-pressure-lowering effects, and low potassium can increase the risk of problems with medicines such as digoxin. People taking hydrochlorothiazide alongside other blood pressure medicines, such as Lisinopril, should follow their prescriber's monitoring advice because combined effects on blood pressure, kidney function and electrolytes are more likely.

Hydrochlorothiazide is classified as a prescription-only medicine in the United Kingdom, and NICE's British National Formulary sets out the professional prescribing detail behind the doses above. Our own checkout does not require a prescription upload to accept an order, and our support team, available 24/7 by email, live chat and phone, includes a pharmacist who can answer questions about your order before or after dispatch. Customers comparing options for blood pressure management may also find it useful to browse our wider Blood Pressure range alongside this listing.