Thiazide-like diuretic Pregnancy: Must not be given during pregnancy or during lactation (contraindicated).

Chlortalidone

Brand names: Hygroton

Chlortalidone is a long-acting thiazide-like diuretic used for hypertension, with strong outcome evidence as an antihypertensive.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: One tablet daily

Route: Oral

Frequency: Once daily

SOURCE CAVEAT: the only eMC bundle provided is for a fixed-dose COMBINATION product (co-tenidone = chlortalidone + atenolol), not single-agent chlortalidone. The SPC states the dose only as 'One tablet daily' for adults and elderly, with no chlortalidone milligram figure. Therefore no standalone chlortalidone mg dose - nor the expected hypertension/oedema range of 12.5 to 50 mg - can be traced to this source. Contraindications, interactions and adverse effects listed below reflect the combination product and include the beta-blocker (atenolol) component as well as the chlortalidone component. Clinician to source a single-agent chlortalidone SPC / current prescribing reference to confirm the milligram dose.

Dose adjustments

Renal

Reduced efficacy in the presence of renal insufficiency; must not be administered to patients with severe renal impairment (contraindicated).

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to the active substances (or to sulphonamide-derived medicinal products) or to any of the excipients
Severe renal failure / severe renal impairment
Bradycardia, cardiogenic shock, hypotension, second- or third-degree heart block, sick sinus syndrome (beta-blocker component)
Metabolic acidosis; severe peripheral arterial circulatory disturbances; untreated phaeochromocytoma; uncontrolled heart failure
Must not be given during pregnancy or lactation

Side effects

Hyperuricaemia, hyponatraemia, hypokalaemia, impaired glucose tolerance (related to chlortalidone)
Bradycardia and cold extremities
Gastrointestinal disturbances (including nausea related to chlortalidone)
Fatigue
Postural hypotension (which may be associated with syncope)

Interactions

Sulfonylureas: beta-blocker component may increase the risk of severe hypoglycaemia and mask warning signs (tachycardia, palpitation, sweating) - monitor blood glucose
Ophthalmic beta-blockers: systemic effects of oral beta-blockers may be potentiated when used concomitantly
Anaesthetic agents: caution required (inform the anaesthetist; choose an agent with as little myocardial depression as possible)

Clinical monograph

How it works

It inhibits sodium-chloride reabsorption in the distal convoluted tubule, producing a sustained diuresis and lowering blood pressure partly through reduced vascular resistance.

Prescribing in practice

Monitor U&E for hypokalaemia and hyponatraemia, which can be clinically significant and develop gradually.
Metabolic effects include hyperglycaemia, hyperuricaemia with gout, and hypercalcaemia.
Use caution in significant renal or hepatic impairment, and review electrolytes more closely in the elderly.

Monitoring

Monitor renal function and electrolytes (especially potassium and sodium) before starting and periodically, and consider checking glucose and urate where relevant.

Counselling the patient

Take it in the morning to reduce night-time urination.
Report muscle cramps, marked weakness or confusion, which may indicate a salt imbalance, and mention any history of gout.

Evidence & guidelines

Guideline-recognised thiazide-like diuretic with robust antihypertensive outcome data (NICE NG136).

Reference: NICE NG136; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

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