Calcium resonium

Also called calcium polystyrene sulfonate

Key points about calcium resonium

  • Calcium resonium is a medicine that's used to treat high potassium levels.
  • Calcium resonium is also called calcium polystyrene sulfonate.
  • Find out how to take it safely and possible side effects.
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Calcium resonium is used to treat high potassium levels. Potassium is a mineral and is essential for keeping your nerves and muscles (including your heart muscles) working properly.

You get potassium from the food you eat. Any excess potassium is removed by your kidneys. If you have kidney problems, levels of potassium can build up in your blood. Too much potassium in your blood can be dangerous as it can cause your heart to beat irregularly. Read more about potassium.

Calcium resonium works by binding itself to potassium in your digestive system, mainly the large intestine (bowel). This helps prevent your body from absorbing too much potassium. People with severe kidney disease often have high potassium levels as their kidneys can't remove potassium from the body.

In Aotearoa New Zealand, calcium resonium is available as a powder. The dose of calcium resonium will be different for different people. It depends on your potassium levels, how often you have dialysis and your response to treatment. 

Always use this medicine exactly as your doctor has told you. Check with your doctor if you're not sure.  

  • Adults: The usual dose for adults is 15 grams 3 to 4 times daily, but some people may need it less often, eg, once daily or only on certain days of the week.
  • Children: The dose depends on how much the child weighs.
  • How long you need to take calcium resonium will depend on the level of potassium in your blood. Your doctor will check your potassium levels to make sure you're taking the right dose, especially if your other medicines have changed recently, or if you've been unwell.

Measuring your dose

Use the spoon provided in the jar of powder to measure your dose. The full, level spoon has 15 grams of powder. You can use ONE level tablespoon if you don't have a scoop.

Mixing the powder

Mix the powder with a little water. If you don't have diabetes, you can mix it with something sweet, such as jam or honey, to make it taste better. DO NOT MIX WITH FRUIT JUICE OR MILK BASED PRODUCTS as these are high in potassium. It's best to use the mixture as soon as it is prepared. Don't store it for longer than 24 hours. If you've been prescribed lactulose liquid and calcium resonium, you can mix the lactulose with the calcium resonium (see below).

Missed doses

If you forget to take your dose, take it as soon as you remember. But if it is nearly time for your next dose, just take the next dose at the right time. Don't take 2 doses at one time or close together.

Here are some things to know when you're taking calcium resonium. Other things may be important as well, so ask your healthcare provider what you should know about.

Taking calcium resonium with lactulose

You may be prescribed lactulose liquid while you are taking calcium resonium.

  • Lactulose liquid helps you pass bowel motions to get rid of potassium from the body once it is bound to resonium.
  • It also helps prevent constipation which is a common side effect of calcium resonium.
  • You will need to keep your bowels working so the potassium can leave your body. Aiming for 1 to 2 soft motions per day is ideal.
  • If you need to restrict your fluid intake, you can mix the lactulose with the calcium resonium. 

Taking other medicines

Take calcium resonium at least 3 hours before or 3 hours after other medicines. Ask your doctor or pharmacist how to time your medicines while you are taking calcium resonium. Taking other medicines at the same time may prevent your body from absorbing the other medicine, and it may not work as well as it should. 

Tell your doctor or pharmacist about all the medicines you are taking. This includes over-the-counter medicines, herbal and complementary medicines and Rongoā Māori. Your doctor or pharmacist will be able to check for any interactions between them.

Avoid products containing sorbitol

Sorbitol is a fruit sugar that is often used as a sweetener in many foods. Avoid eating or drinking anything that contains sorbitol (eg, chewing gum, diet drinks, baked goods, or frozen desserts made with sorbitol) as it can increase your risk of side effects.

Like all medicines, calcium resonium can cause side effects, although not everyone gets them. 

Side effects What should I do?
  • Constipation (unable to poo)
  • Tell your doctor immediately.
  • Nausea (feeling sick)
  • Indigestion
  • Diarrhoea (runny poos)
  • Tummy upset
  • Tell your doctor if these are bothering you.
  • Muscle cramps
  • Loss of appetite
  • Tell your doctor if these are bothering you.
  • Signs of high potassium levels such as muscle weakness, general weakness or tiredness, nausea, muscle pain or cramps, difficulty breathing, unusual heartbeat, chest pains 
  • Tell your doctor immediately or ring Healthline 0800 611 116.
  • Signs of an allergic reaction such as a rash or swelling of the face, lips, mouth or throat
  • Hives or itchy skin
  • Tell your doctor immediately or ring Healthline 0800 611 116.
Did you know that you can report a side effect to a medicine to CARM (Centre for Adverse Reactions Monitoring)? Report a side effect to a product.(external link)

The following link has more information on calcium resonium.

Calcium resonium factsheet [PDF, 288 KB] Health Navigator NZ, 2022 English [PDF, 288 KB], Chinese (simplified) [PDF, 759 KB], Chinese (traditional) [PDF, 1008 KB]
Calcium resonium(external link) Medsafe Consumer Information, NZ


  1. Calcium resonium(external link) NZ Formulary, NZ


calcium resonium
Calcium resonium factsheet
Health Navigator NZ, 2022
5 questions to ask about your medications
5 questions to ask about your medications
Health Quality and Safety Commission, NZ, 2019

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Credits: Sandra Ponen, Pharmacist, Healthify He Puna Waiora. Healthify is brought to you by Health Navigator Charitable Trust.

Reviewed by: Angela Lambie, Pharmacist, Auckland

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