Kayexalate (Sodium polystyrene sulfonate)

Pronunciation: kay-EX-uh-late.

Generic name
sodium polystyrene sulfonate (also available as calcium polystyrene sulfonate)
Drug class
Cation-exchange resin (potassium-lowering agent)
Form
Powder for oral or rectal suspension
Route
Oral or rectal (enema)
Legal status
Prescription-only medicine

Availability and supply rules vary by country

Trade names by country: United States · United Kingdom · Canada · Australia · New Zealand

Australia: Resonium A (sodium form) (5), Calcium Resonium (calcium form) (5) · Full directory

What sodium polystyrene sulfonate (also available as calcium polystyrene sulfonate) is and how it works

Kayexalate (sodium polystyrene sulfonate) and its calcium-form equivalent (Calcium Resonium) are prescription cation-exchange resins used to treat hyperkalaemia (too much potassium in the blood). They work by binding potassium in the gut in exchange for sodium or calcium, which is then eliminated in the stool. (1) (4)

This medicine carries a real, serious risk of fatal bowel injury (intestinal necrosis, ischaemic colitis, or bowel perforation), which is worse if it is taken together with sorbitol -- your prescriber and pharmacist will make sure sorbitol is not combined with it. It should only be used if your bowels are working normally, and you must seek urgent medical help for any new severe abdominal pain, vomiting, or bleeding. Because it can lower potassium slowly (over hours to days), it is not used alone for a potassium emergency.

Mechanism of action: how sodium polystyrene sulfonate (also available as calcium polystyrene sulfonate) works

Sodium/calcium polystyrene sulfonate is a non-absorbed cation-exchange resin that releases sodium or calcium ions in exchange for potassium ions as it passes through the gastrointestinal tract, most effectively in the large intestine. The exchange efficiency is limited and variable (approximately 33% in vivo), so electrolyte balance must be monitored directly rather than assumed from the dose given. (2) (4)

What sodium polystyrene sulfonate (also available as calcium polystyrene sulfonate) is used for

Hyperkalaemia (high blood potassium)

Used to treat elevated blood potassium levels, most often in people with kidney problems or those on dialysis, when potassium needs to be lowered over hours to days. (1) (3) (4)

Before taking sodium polystyrene sulfonate (also available as calcium polystyrene sulfonate)

Do not take / not appropriate for

  • Do not take this medicine if your blood potassium level is already low (hypokalaemia) or below 5 mmol/L, as directed by your prescriber's testing. (all countries) (1) (3) (4)
  • Do not take this medicine if you have a bowel obstruction (obstructive bowel disease), or if you are a neonate (it should not be given by mouth to newborns). (all countries) (1) (3) (4)
  • Do not take this medicine together with sorbitol -- this combination has been strongly linked to fatal bowel injury (intestinal necrosis). (all countries) (1) (3) (4)
  • Do not take the calcium form (Calcium Resonium) if you have a condition causing high blood calcium (hyperparathyroidism, multiple myeloma, sarcoidosis, or certain cancers). (United Kingdom, Australia, European Union) (3)
  • Do not take this medicine if you have a history of hypersensitivity to polystyrene sulfonate resins. (all countries) (1) (4)

Tell your clinician about

  • Any history of bowel disease, recent bowel surgery, or reduced gut motility.
  • Whether you are dehydrated (hypovolaemic) or premature/a very young infant.
  • Whether you have severe heart failure, severe high blood pressure, or marked swelling (oedema), which affects whether the sodium form is suitable for you.
  • Whether you are on digoxin or another heart medicine affected by potassium levels.
  • All other medicines you take by mouth, since this medicine needs to be timed at least 3 hours apart from them.
(1) (3) (4)

How to take sodium polystyrene sulfonate (also available as calcium polystyrene sulfonate)

  • Take exactly as prescribed, usually mixed into a small amount of water or a suitable liquid (not fruit juice, which contains potassium) as directed.
  • Take other oral medicines at least 3 hours before or after this medicine (6 hours if you have gastroparesis), since it can bind to them and reduce their absorption.
  • Never take this medicine together with sorbitol.
  • This medicine works over hours to days -- it is not a fast-acting treatment for a potassium emergency, and other measures may be used alongside it if your potassium is dangerously high.
  • Sit upright and take your time when swallowing the suspension to avoid inhaling it.
(1) (3) (4)

Procedures and treatment changes

Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2) (3) (4) (5) (6) (7) (8)

Missed dose

This medicine is usually given under close clinical supervision with regular blood tests, often in a hospital or dialysis setting. Contact your care team for guidance on a missed dose rather than adjusting your own schedule.

Overdose

Seek urgent medical attention if you think you have taken too much, or if you develop severe constipation, severe abdominal pain, or signs of low potassium (irritability, confusion, muscle weakness, or an irregular heartbeat). (2) (4)

Side effects

Side effects and their urgency vary; report severe, persistent, or concerning symptoms.

Constipation.

What to notice: Constipation.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Nausea, vomiting, or loss of appetite.

What to notice: Nausea, vomiting, or loss of appetite.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Diarrhoea, especially if too much is taken.

What to notice: Diarrhoea, especially if too much is taken.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (4)

Serious warnings

Signs of serious bowel injury (intestinal necrosis, ischaemic colitis, or perforation) — emergency

Symptoms: Severe or worsening abdominal pain, nausea and vomiting, stomach distension (bloating/swelling), or rectal bleeding.

Action: Seek emergency medical help immediately -- this is a real, well-documented, sometimes fatal risk, most strongly linked to taking this medicine together with sorbitol. Do not wait to see if symptoms improve on their own. (1) (3) (4)

Signs of low blood potassium (hypokalaemia) — high caution

Symptoms: Irritability, confusion, delayed thinking, unusual muscle weakness, or an irregular heartbeat.

Action: Contact your care team promptly for a blood potassium check -- this medicine can lower potassium too far, and the effect can be more dangerous in people taking digoxin or similar heart medicines. (2) (4)

Signs of severe constipation or bowel blockage — high caution

Symptoms: No bowel movement for several days, worsening abdominal bloating, or inability to pass gas.

Action: Contact your care team promptly -- treatment is generally stopped until normal bowel movement resumes, since ongoing use with constipation raises the risk of serious bowel injury. (2) (3)

Signs of breathing problems after taking a dose (aspiration) — high caution

Symptoms: Coughing, choking, or breathing difficulty during or shortly after taking the suspension.

Action: Seek urgent medical attention -- inhaling this resin can cause lung complications; always sit upright and take it slowly. (4)

Interactions

  • Sorbitol: co-administration is not recommended/contraindicated because of the strongly increased risk of fatal intestinal necrosis. (1) (3) (4)
  • Other oral medicines: this resin can bind to them in the gut and reduce their absorption -- take other oral medicines at least 3 hours before or after (6 hours if you have gastroparesis). (3) (4)
  • Magnesium-containing antacids or laxatives: should not be combined -- systemic alkalosis has been reported with cation-donating antacids/laxatives taken alongside this class of resin. (2) (4)
  • Digoxin and similar heart medicines: their toxic effects can be worsened if this medicine causes low potassium. (2) (4)

Pregnancy, breastfeeding, kidney/liver function, age

Pregnancy

Discuss use with your prescriber; specific pregnancy safety data were not detailed in the sources reviewed for this dossier. (1) (2) (3) (4) (5) (6) (7) (8)

Children

Not given by mouth to neonates; paediatric dosing (when used) is calculated individually by the prescriber based on body weight and potassium level. Particular care is needed with rectal administration in children and neonates because of the risk of resin impaction. (1) (2) (3) (4) (5) (6) (7) (8)

Elderly

No specific dose adjustment based on age alone is described in the sources reviewed, but the same bowel-injury and electrolyte risks apply and may need closer monitoring in frail patients. (1) (2) (3) (4) (5) (6) (7) (8)

Hepatic_impairment

No specific guidance identified in the sources reviewed for this dossier. (1) (2) (3) (4) (5) (6) (7) (8)

Renal_impairment

This medicine is commonly used specifically in the context of kidney disease/dialysis-related hyperkalaemia; dosing and monitoring are individualised by the treating team. (1) (2) (3) (4) (5) (6) (7) (8)

Monitoring

Before starting

  • Confirmation of normal bowel function before starting
  • Baseline serum potassium, sodium, calcium, and magnesium
  • Review for any history of bowel disease, recent surgery, or reduced gut motility

During treatment

  • Serum potassium checked at least daily, and more frequently if clinically needed.
  • Monitoring for other electrolyte disturbances (sodium, calcium, magnesium).
  • Prompt clinical assessment for any new abdominal pain, distension, vomiting, or bleeding.
  • Weekly serum calcium monitoring specifically for the calcium form (Calcium Resonium).
(4) (3)

Storage

Store at room temperature, protected from moisture, out of reach of children.

Professional information

Clinician-facing context only, sourced from the current US DailyMed label, the FDA's archived Kayexalate label, the UK EMC Calcium Resonium SmPC, and a real, current (June 2022) Sanofi Canada prescribing information PDF; verify against the current full label before prescribing.

United States

Indication: Hyperkalaemia (sodium form)

Dose summary: 15 g (60 mL) to 60 g (240 mL) daily, typically 15 g one to four times daily; rectal 30-50 g every 6 hours.

Renal context: Used specifically in the context of renal insufficiency/failure-related hyperkalaemia; no separate numeric renal dose-adjustment table identified in this label. (1)

Canada

Indication: Hyperkalaemia (sodium form)

Dose summary: Individualised, adjusted to serum potassium response; a single 15 g dose delivers approximately 60 mmol of sodium -- caution in patients who cannot tolerate a sodium load, where the calcium form may be preferred.

Renal context: Used specifically in the context of renal disease/dialysis-related hyperkalaemia. (4)

United Kingdom

Indication: Hyperkalaemia (calcium form, Calcium Resonium)

Dose summary: 15 g three to four times daily; weekly serum calcium monitoring given the calcium-form-specific hypercalcaemia risk.

Renal context: Indicated specifically for patients with anuria, severe oliguria, or those on/requiring dialysis. (3)

Mechanism of action

Hepatic guidance

No specific hepatic dosing guidance identified in the sources reviewed for this dossier.

Overdose note

Overdose can cause severe hypokalaemia and other electrolyte disturbances; management is supportive with close electrolyte and cardiac monitoring. (2) (4)

Frequently asked questions

Does Kayexalate have a boxed (black box) warning?

No -- the current US, UK, and Canadian labels do not format the bowel-injury risk as a formal boxed warning. However, every label carries a very serious, prominently highlighted Warnings section describing a real, sometimes fatal risk of intestinal necrosis and other bowel injury, which is worse when combined with sorbitol. This risk should be taken exactly as seriously as a boxed warning, even though it is not formatted as one. (1) (2) (3) (4)

What is the difference between the sodium form (Kayexalate) and the calcium form (Calcium Resonium)?

Both work the same way and carry the same core bowel-injury and sorbitol risks. The sodium form delivers a real, quantified sodium load (about 60 mmol of sodium per 15 g dose), so the calcium form is often preferred for patients who cannot tolerate extra sodium, such as those with severe heart failure or severe high blood pressure -- but the calcium form needs its own extra monitoring for high blood calcium. (4) (3)

Is this medicine available in every country?

It is authorised as a prescription medicine in the United States, United Kingdom, Canada, Australia, and across the European Union (via national authorisation). In New Zealand, the sodium form (Resonium A) is Medsafe-approved, while the calcium form (Calcium Resonium) is only available through an unapproved-medicine access pathway. (1) (3) (4) (5) (6) (7) (8)

What is the mechanism of action of sodium polystyrene sulfonate (also available as calcium polystyrene sulfonate)?

Sodium/calcium polystyrene sulfonate is a non-absorbed cation-exchange resin that releases sodium or calcium ions in exchange for potassium ions as it passes through the gastrointestinal tract, most effectively in the large intestine. The exchange efficiency is limited and variable (approximately 33% in vivo), so electrolyte balance must be monitored directly rather than assumed from the dose given. (2) (4)

What is the generic name of Kayexalate (Sodium polystyrene sulfonate)?

The generic name is sodium polystyrene sulfonate (also available as calcium polystyrene sulfonate). (1) (3)

What class of drug is sodium polystyrene sulfonate (also available as calcium polystyrene sulfonate)?

Kayexalate (Sodium polystyrene sulfonate) is classed as: Cation-exchange resin (potassium-lowering agent). (1) (3)

References

  1. Sodium Polystyrene Sulfonate Suspension -- full prescribing informationDailyMed (U.S. National Library of Medicine) -- FDA prescribing information · United States · accessed 2026-07-30 · source 1
  2. Kayexalate (sodium polystyrene sulfonate, USP) -- approved label, revised December 2010U.S. Food and Drug Administration (accessdata.fda.gov) -- approved drug label archive · United States · accessed 2026-07-30 · source 2
  3. Calcium Resonium 99.934% w/w Powder for Oral/Rectal Suspension -- Summary of Product Characteristics (SmPC)electronic medicines compendium (emc), United Kingdom -- Summary of Product Characteristics · United Kingdom · accessed 2026-07-30 · source 3
  4. KAYEXALATE (Sodium Polystyrene Sulfonate) -- Prescribing Information, revised 24 June 2022sanofi-aventis Canada Inc. -- Health Canada-authorised Prescribing Information · Canada · accessed 2026-07-30 · source 4
  5. Resonium A (sodium polystyrene sulfonate, ARTG 15497) and Calcium Resonium (calcium polystyrene sulfonate, ARTG 12567)Therapeutic Goods Administration (TGA), Australia -- ARTG entries · Australia · accessed 2026-07-30 · source 5
  6. Polystyrene sulfonate: list of nationally authorised medicinal products (PSUSA/00002472)European Medicines Agency (EMA) -- PSUSA nationally-authorised product list · European Union · accessed 2026-07-30 · source 6
  7. Resonium A (sodium polystyrene sulfonate) -- New Zealand Data SheetMedsafe (New Zealand Medicines and Medical Devices Safety Authority) -- approved New Zealand Data Sheet · New Zealand · accessed 2026-07-30 · source 7
  8. Calcium Resonium -- medicine supply noticePharmac (Te Pataka Whaioranga, New Zealand Government medicines-funding agency) · New Zealand · accessed 2026-07-30 · source 8

Brand names by country

Single-ingredient sodium polystyrene sulfonate (also available as calcium polystyrene sulfonate) names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.

Priority countries

United States

  • Kionex15 g/60mL · ani pharmaceuticals, inc.

United Kingdom

  • Calcium Resonium (3)MHRA licensed confirmed · 99.934% w/w powder · Sanofi

Canada

  • SOLYSTAT
  • RESONIUM CALCIUM
  • KAYEXALATE
  • K-EXIT POUDRE

Australia

  • Resonium A (sodium form) (5)TGA ARTG confirmed · powder · not independently confirmed beyond ARTG search index
  • Calcium Resonium (calcium form) (5)TGA ARTG confirmed registered since 1991 · powder · Sanofi-Aventis Australia Pty Ltd

New Zealand

  • Resonium A (sodium form) (7)Medsafe approved confirmed live data sheet · powder · not independently confirmed beyond the data sheet
  • Calcium Resonium (calcium form) (8)not Medsafe approved accessed via section 29A unapproved medicine pathway · powder · not independently confirmed
View brands in additional countries.

European Union

Resonium A Pulver (Austria) (6), Kayexalate Calcium / Kayexalate Sodium (Belgium) (6), Calcium Resonium (Czech Republic) (6)

This page provides general reference information about Kayexalate (sodium polystyrene sulfonate) and calcium polystyrene sulfonate, and is not a substitute for advice from the prescriber or dialysis team managing your treatment. Seek emergency medical help immediately for any severe abdominal pain, vomiting, or bleeding while taking this medicine.

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