Chlorthalidone: Uses, Interactions and Safety

Uses

Chlorthalidone, also called chlortalidone, is a long-acting thiazide-like diuretic used for high blood pressure and, in some products, oedema associated with heart, liver or kidney disease. It increases urinary salt and water excretion. The Turkish 2025 hypertension consensus discusses its role in resistant hypertension; this page does not establish Turkish marketing approval.

Administration

This summary concerns oral single-ingredient tablets described in foreign labels. They are generally taken in the morning with food according to the prescription. Different chlorthalidone products may have formulation differences; a prescriber or pharmacist should oversee substitutions. Do not add a second diuretic simply because swelling persists.

Safety

Do not use with anuria or a known relevant sulfonamide/chlorthalidone hypersensitivity. Fluid loss can cause dizziness and worsen kidney function. Blood tests assess sodium, potassium, magnesium and kidney function. Gout, diabetes and liver disease need additional attention. Severe weakness, confusion, palpitations, fainting or markedly reduced urine require prompt assessment.

Interactions

Lithium clearance may fall, producing toxicity; levels require close monitoring if treatment is combined. Low potassium can increase digoxin toxicity and sotalol-related rhythm risks. Systemic corticosteroids can worsen potassium loss. Other blood-pressure medicines may be deliberately combined but increase the chance of hypotension. Insulin or sulfonylurea requirements can change.

Pregnancy and breastfeeding

Chlorthalidone is not first-line treatment for hypertension in pregnancy and is not routinely used for normal pregnancy swelling. Fetal or newborn electrolyte problems, jaundice and other effects have been reported with thiazide exposure. It enters breast milk and may accumulate; the Thalitone information advises against breastfeeding during treatment.

Adverse effects

Dizziness, nausea, cramps and changes in electrolytes, uric acid or glucose are reported. Frequency cannot be estimated reliably from the general label. Alcohol may worsen postural dizziness. Attend the planned blood tests even when there are no symptoms.

Sources

• Chlorthalidone prescribing information
• Turkish Hypertension Consensus Report 2025
• Thalitone (chlorthalidone): US prescribing information

Additional verified references

• ATC/DDD Index: chlortalidone