An injectable calcium salt used in hospital emergencies
Calcium chloride
An injectable calcium salt given in hospital for dangerously low calcium, high potassium and some overdoses, with a high risk of tissue damage if it leaks from the vein.
What is Calcium chloride?
Calcium chloride is an injectable calcium salt used in hospital, usually in emergencies, to treat dangerously low calcium in the blood, to protect the heart when potassium is dangerously high, and in some overdoses such as those involving certain heart medicines. The most important safety point is that it is very irritant and can cause severe tissue damage if it leaks out of the vein, so it is given carefully and usually through a secure or central line, slowly, with heart monitoring. It can affect the heart's rhythm if given too fast and must not be mixed with bicarbonate, which would cause a harmful precipitate. It is given only by trained staff.
Education and reference only. This is a plain-language guide to Calcium 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
Calcium chloride is a concentrated, injectable form of calcium given into a vein, almost always in a hospital and often in an emergency. It is used when blood calcium is dangerously low, to steady and protect the heart when blood potassium is dangerously high, and in certain poisonings, such as overdoses of some heart medicines (calcium-channel blockers) or after exposure to certain chemicals. Compared with calcium gluconate, it provides more calcium for the same volume but is harsher on the veins. Because of its strength and its risks, it is handled only by trained healthcare staff in a monitored setting.
How it works
Calcium is essential for the normal working of nerves, muscles and especially the heart. When blood calcium falls too low, or when potassium rises too high, the heart's electrical activity can become dangerously unstable; giving calcium quickly restores and stabilises this activity. In some overdoses it can partly counter the effects of medicines that block calcium's normal action. Because it works fast and powerfully on the heart, it is given slowly and with continuous heart monitoring so its effect can be watched closely and the dose adjusted to the situation.
Company & origin
Originated / developed by: Generic (hospital manufacturers).
An injectable calcium salt used in UK hospitals to treat dangerously low calcium, high potassium and certain emergencies.
Practical use
How to take Calcium chloride
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- It is given by trained hospital staff as an injection into a vein, not something you take yourself.
- It is given slowly and with heart monitoring, because giving it too fast can disturb the heart's rhythm.
- It is given through a secure or central line where possible, because leakage from the vein can cause severe tissue damage.
- It is never mixed in the same line with bicarbonate or phosphate, which would form a harmful precipitate.
- Tell staff at once if the injection site becomes painful, red or swollen, as this can signal leakage.
Weighing it up
Advantages & disadvantages of Calcium chloride
Advantages
- Acts quickly to treat dangerously low calcium and to protect the heart when potassium is dangerously high.
- Provides a concentrated source of calcium, useful in emergencies and certain overdoses.
- A long-established emergency treatment given under close hospital monitoring.
Disadvantages
- Very irritant, with a high risk of severe tissue damage if it leaks from the vein.
- Can cause dangerous heart-rhythm changes or a slow heartbeat if given too fast.
- Must not be mixed with bicarbonate or phosphate, and is for hospital use only.
Practical use
Good to know
The single most important thing about calcium chloride is that it is very irritant: if it leaks out of the vein into the surrounding tissue it can cause severe damage, including tissue death, so it is given through a well-placed or central line and the site is watched closely. It must be given slowly, because giving it too fast can cause dangerous changes in the heart's rhythm, a slow heartbeat or a feeling of heat and flushing. A key practical rule is that it must never be mixed in the same line with sodium bicarbonate or phosphate, as this forms a solid precipitate that can block the line and harm the patient. It is an emergency hospital medicine, not something used at home, and it is given by staff trained to handle it with heart monitoring throughout.
Who should not take it / use with caution
- It is avoided in people whose blood calcium is already high.
- It is used with great caution, or avoided, in people taking digoxin, because calcium can worsen digoxin's effects on the heart.
- It is given only by trained staff in a monitored setting, with care over the choice of vein.
Monitoring
- Continuous heart monitoring during and after the injection.
- Close watching of the injection site for any sign of leakage and tissue damage.
- Checking blood calcium, potassium and other minerals to guide treatment.
Side effects
- Severe tissue damage if it leaks out of the vein, which is the main risk.
- A slow heartbeat, heart-rhythm changes, flushing or a feeling of heat, especially if given too fast.
- A chalky taste, nausea or a fall in blood pressure during the injection.
Key interactions
- It can dangerously increase the effects of digoxin on the heart, so the two are used together only with great care.
- It forms a harmful precipitate if mixed with sodium bicarbonate or phosphate in the same line.
- It can affect how some other medicines and minerals behave, so it is given on its own under supervision.
Available as: A solution for injection into a vein, given in hospital.
Answers
Calcium chloride: frequently asked questions
What is calcium chloride used for?
It is an injectable calcium salt used in hospital for dangerously low calcium, to protect the heart when potassium is dangerously high, and in some overdoses such as those involving certain heart medicines.
Why must it be given so carefully?
It is very irritant and can cause severe tissue damage if it leaks out of the vein, so it is given slowly through a secure line with heart monitoring.
How is it different from calcium gluconate?
Calcium chloride provides more calcium for the same volume but is harsher on the veins, so calcium gluconate is often preferred when access is less secure.
Why can it not be mixed with bicarbonate?
Mixing calcium chloride with sodium bicarbonate or phosphate forms a solid precipitate that can block the line and harm the patient, so they are kept apart.
Can I have it at home?
No. It is a concentrated emergency medicine given only by trained hospital staff with heart monitoring, not something used at home.
Authoritative sources
- BNF
- NICE CKS
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