Chlorthalidone: Price, Dosage & Where to Buy

Chlorthalidone is a diuretic, often called a water tablet, used mainly to treat high blood pressure. It helps the kidneys remove extra salt and water, and may be used alone or alongside other blood pressure medicines. Chlorthalidone is available as a generic medicine and requires a prescription in the United Kingdom.

Chlorthalidone is used to manage high blood pressure. It can be used alone or alongside other medicines to increase their blood pressure-lowering effect when hypertension is more severe. It is also used as an additional treatment for oedema, which means swelling caused by retained fluid.

This includes fluid retention linked to congestive heart failure, liver cirrhosis, and treatment with corticosteroids or oestrogens. The label also lists fluid retention associated with kidney conditions, including nephrotic syndrome, acute glomerulonephritis and chronic kidney failure. Its use for swelling during pregnancy depends on the cause and requires careful consideration by a doctor.

The label lists oral tablets in strengths of 12.5 mg, 15 mg, 25 mg and 50 mg. Treatment is described as starting at the lowest possible dose, with adjustments based on the patient's response. The label lists a single morning dose with food, rather than divided daily doses.

The usual starting dose is 25 mg once daily for high blood pressure. The label lists increases to 50 mg once daily and then 100 mg once daily if further control is needed, or the addition of another blood pressure medicine. The label lists doses above 100 mg daily as usually offering no increase in effectiveness for high blood pressure.

The label lists initial adult oedema doses of 50 to 100 mg daily, or 100 mg on alternate days. The label lists higher oedema doses for some patients, up to 200 mg daily. Maintenance treatment may use lower doses, adjusted to the individual's response.

As a diuretic, chlorthalidone acts on the kidneys and reduces the amount of salt that is returned to the blood during urine formation. More salt leaves the body in urine, and water follows it. This reduces excess fluid and can help ease swelling.

Reducing the amount of fluid circulating in the blood also helps lower blood pressure. Diuretics can change the balance of minerals, such as potassium, in the blood as well as the amount of water in the body.

Animal studies found no evidence of harm to the unborn young, but adequate, well-controlled studies in pregnant women are lacking. Chlorthalidone should be used during pregnancy only if clearly needed, after weighing benefits against possible risks. Related diuretics cross the placenta.

Possible risks include jaundice and low platelet counts in the unborn or newborn baby. Routine diuretic use in an otherwise healthy pregnant woman is inappropriate. The label does not specify breastfeeding information; discuss breastfeeding with a doctor or pharmacist.

A missed dose can interrupt the regular effect of a diuretic. General pharmacy advice is not to double a dose to make up for one that was missed. Check the dispensing label or ask a pharmacist for advice about resuming the prescribed schedule, especially if the next dose is near.

Store at 20° to 25°C. Keep the tablets in a tight, light-resistant container and protect them from light.

Keep this medicine out of the reach of children. Some unit-dose packs are not child resistant.