A potassium supplement for low potassium levels
Potassium chloride
A medicine used to replace potassium when blood levels are too low, taken by mouth or given as a carefully diluted drip in hospital.
What is Potassium chloride?
Potassium chloride is used to replace potassium when blood potassium levels are too low, which can happen with some water tablets, vomiting or diarrhoea, or certain illnesses. It can be taken by mouth as tablets or liquid, or given in hospital as a drip into a vein when levels are very low. The most important safety point is that the concentrated injection must never be given undiluted or quickly into a vein, because this can stop the heart; it is always diluted and given slowly with heart and blood monitoring. Oral forms can irritate the gut and are taken with food and plenty of water.
Education and reference only. This is a plain-language guide to Potassium chloride — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Potassium chloride is a form of the mineral potassium, which the body needs for the heart, nerves and muscles to work properly. It is used when blood potassium falls too low, a state called hypokalaemia, which can be caused by some diuretics (water tablets), prolonged vomiting or diarrhoea, or certain hormone and kidney problems. It comes as tablets, effervescent tablets or liquid to take by mouth, and as a concentrated solution that is diluted and given as a drip into a vein in hospital. The injectable form is treated with great care because of its effect on the heart.
How it works
Potassium chloride simply tops up the body's stores of potassium, restoring levels to a safe range so that the heart rhythm, nerves and muscles function normally. When taken by mouth it is absorbed gradually from the gut; given as a slow, diluted drip it raises blood potassium more directly when levels are dangerously low. Because both too little and too much potassium can disturb the heart, the aim is always to correct the level steadily rather than quickly, which is why the drip form is diluted, given slowly and monitored closely.
Company & origin
Originated / developed by: Generic (long-established).
A long-established medicine used in the UK to replace potassium when blood potassium levels are too low, given by mouth or, in hospital, by a carefully diluted drip into a vein.
Practical use
How to take Potassium chloride
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Take oral tablets or liquid with or after food and with a full glass of water to reduce gut irritation.
- Stay sitting or standing for a while after taking it, and do not lie down straight away.
- Swallow modified-release tablets whole and do not crush or chew them unless told otherwise.
- Never let anyone give the concentrated injection undiluted or quickly into a vein; it is always diluted and given slowly in hospital.
- Attend the blood tests you are asked to have so your potassium level can be checked and the dose adjusted.
Weighing it up
Advantages & disadvantages of Potassium chloride
Advantages
- An effective way to correct low potassium and protect the heart, nerves and muscles.
- Available as oral forms for milder cases and as a carefully controlled drip for severe ones.
- A long-established treatment with decades of experience behind its use.
Disadvantages
- The concentrated injection is dangerous if given undiluted or fast, as it can stop the heart.
- Oral forms can irritate the gut and cause nausea or stomach discomfort.
- Too much potassium is also harmful, so blood monitoring is needed.
Practical use
Good to know
The single most important safety point with potassium chloride is about the concentrated injection: it must never be given undiluted or rapidly into a vein, because a sudden rise in potassium can stop the heart. In hospital it is always well diluted, given slowly through a drip, and used with heart-rhythm and blood-potassium monitoring. With the oral forms, the main thing to know is that potassium can irritate the gut, so tablets and liquid are taken with or after food and with plenty of water, and you should stay upright for a while afterwards to avoid irritation. Both too little and too much potassium are dangerous, so blood tests are used to guide treatment, especially in people with kidney problems or those taking other medicines that affect potassium.
Who should not take it / use with caution
- People with high blood potassium (hyperkalaemia) should not take it, as it would make things worse.
- It is used with great caution in people with kidney problems, who clear potassium less well.
- It is used with care alongside other medicines that raise potassium, under medical guidance.
Monitoring
- Regular blood tests to check potassium and keep it in a safe range.
- Heart-rhythm monitoring when potassium is given by drip or levels are very abnormal.
- Checking kidney function and other potassium-affecting medicines.
Side effects
- Nausea, stomach discomfort or diarrhoea, especially with oral forms taken without food.
- Irritation of the gullet or gut if tablets are not taken with enough water or while upright.
- Dangerously high potassium if too much is given, which can disturb the heart rhythm.
Key interactions
- Medicines such as ACE inhibitors, ARBs and potassium-sparing water tablets raise potassium and need careful combining.
- Some other medicines and salt substitutes also add potassium, so tell your prescriber everything you take.
- Kidney function affects how potassium is handled, so dosing is adjusted accordingly.
Available as: Tablets, effervescent tablets and liquid taken by mouth, and a concentrated solution that is diluted and given as a drip into a vein in hospital.
Answers
Potassium chloride: frequently asked questions
What is potassium chloride used for?
It is used to replace potassium when blood levels are too low, which can happen with water tablets, vomiting or diarrhoea, or certain illnesses, helping the heart, nerves and muscles work properly.
Why must the injection never be given undiluted or fast?
Giving concentrated potassium straight into a vein, or too quickly, can cause a sudden dangerous rise in potassium that can stop the heart, so it is always well diluted and given slowly with monitoring.
Why do the tablets upset my stomach?
Potassium can irritate the gut, so the tablets and liquid are taken with or after food and a full glass of water, staying upright afterwards to reduce irritation.
Can I take too much potassium?
Yes. Too much potassium is just as dangerous as too little and can disturb the heart rhythm, which is why blood tests are used to guide the dose.
Do I need blood tests while taking it?
Yes. Regular blood tests check your potassium level so the dose can be adjusted, particularly if you have kidney problems or take other medicines that affect potassium.
The wider class
About Potassium supplement (electrolyte replacement)
Potassium chloride belongs to the potassium supplement (electrolyte replacement) class. For how the class as a whole works, its shared safety principles and monitoring, see the full guide.
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Authoritative sources
- BNF
- NICE CKS
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