Meds and you

27 September 2013


Chlortalidone is a diuretic. Diuretics are drugs that increase the production of urine, thereby removing excess water from the body.


(Also known as chlorthalidone)

Chlortalidone is the active ingredient of Hygroton tablets (Nappi Code: 731919-009).

General information Chlortalidone is a diuretic. Diuretics are drugs that increase the production of urine, thereby removing excess water from the body.

In South Africa chlortalidone is registered for the treatment of oedema - an accumulation of excessive amounts of fluid in body tissue resulting in swelling - that results from conditions such as congestive heart failure, kidney disorders, etc. It is also used for the treatment of mild to moderately high blood pressure.

Chlortalidone is not a cure for high blood pressure, but is effective in keeping it under control. For it to be effective you must take it regularly. High blood pressure declines slowly and it may take a few weeks for chlortalidone to reach its full effect. Keep taking this medicine during this period, even if you are feeling better or fail to notice any improvement.

The first couple of doses of this medication may cause a sudden drop in blood pressure which may cause dizziness or blackouts when you suddenly get up. It is therefore advised to be resting when starting treatment and to lie down for 2 hours afterwards.

The diuretic should best be taken in the morning to prevent additional night-time visits to the toilet. It is possible that you may produce a larger volume of urine at the start of treatment with chlortalidone. Be aware of where your nearest ablution facilities are if you are away from home!

Chlortalidone enhances the excretion of potassium from your body and may warrant a potassium-rich diet (foods such as bananas or tomatoes), or even the use of a potassium supplement.

A low sodium diet is furthermore advised as this may diminish potassium loss, and also lower the dosage requirements for this drug.

How does chlortalidone work?
A diuretic such as chlortalidone reduces the overall fluid volume in the body, thereby reducing pressure within blood vessels.

Fast facts

Drug schedule: schedule 3
Available as: chlortalidone is available as tablets.
What does it do? Chlortalidone lowers blood pressure and reduce fluid volume in the body.
Overdose risk: low
Dependence risk: low
Is chlortalidone available as a generic? yes
Is chlortalidone available on prescription only? Yes

User information

Dietary advice: chlortalidone enhances the excretion of potassium from your body and may warrant a potassium-rich diet containing foods such as bananas or tomatoes.
Stopping this medicine: it may be dangerous to discontinue this drug abruptly as symptoms of the condition being treated may recur. Don't discontinue this drug without speaking to your doctor.
Prolonged use: prolonged use may result in an electrolyte disturbance. Kidney function may also need to be evaluated periodically.

Special precautions
Consult your doctor before using this drug if:

  • you have kidney or liver disease

  • you have known low blood levels of potassium or high blood levels of calcium

  • you have gout

  • you have diabetes

  • you are allergic to sulphonamide-drugs

  • you are pregnant

  • you have been diagnosed with arteriosclerosis

  • you have been diagnosed with Addison’s disease

  • you are taking other medication

Pregnancy: avoid. Potential risk to the foetus has been reported. Consult your doctor before use, or if you are planning to fall pregnant.
Breastfeeding: avoid. This medication is passed through breast milk and may affect your baby adversely. Consult your doctor before use.
Infants and children: if used in children the dose must be determined by a paediatrician.
The elderly: caution is advised in the elderly as adverse effects may be more likely.
Driving and hazardous work: caution is advised as use of this medication may lead to dizziness and light-headedness. Avoid such activities until you know how this medication affects you.
Alcohol: avoid concomitant use of alcohol with this medication.

Possible side effects

Side Effect
Consult your doctor

Only if severe
In all cases
muscle cramps or pain








thirst/dry mouth




loss of appetite




increased blood sugar


skin rash/itch


swelling of mouth/difficulty breathing


visual disturbance


yellow tinge of skin/eyes




Drug interactions

ACE inhibitor drugs increased dizziness at start of treatment
alcohol, barbiturates increased dizziness at start of treatment
allopurinol, tetracycline antibiotics increased risk of chlortalidone toxicity
cholestyramine reduced absorption of chlortalidone
corticosteroids reduced diuretic effect/risk of potassium depletion
digoxin increased risk of toxicity in case of potassium depletion
terfenadine, sotalol, pimozide risk of heart rhythm disturbance
lithium risk of lithium toxicity
non-steroidal anti-inflammatory drugs reduced diuretic effect/increased risk of kidney damage
oral anti-diabetic drugs blood sugar lowering effect may be reduced
co-trimoxazole, trimethoprim reduced sodium levels in body
vitamin D increased risk of high calcium blood levels

Disease interactions
Consult your doctor before using this drug if you have kidney or liver disease, gout, diabetes, Addison’s disease or if you have been diagnosed with arteriosclerosis.

Overdose action
A small overdose is no cause for concern. In case of intentional large overdose seek emergency medical attention.

Recommended dosage
Adults: oral, 12.5-50 mg/day

This material is not intended to substitute medical advice, but is for informational purposes only. Please consult a physician for specific treatment and recommendations.

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