Sodium Polystyrene Sulfonate is a prescription medication that lowers dangerously high potassium levels in the blood by binding to potassium in the intestines and removing it through the stool.

If your doctor has prescribed this medication — or you've seen it referred to as Kayexalate, Kionex, or SPS — this guide covers everything you need to know in plain language: what it does, how to take it, who should avoid it, and how much it costs in 2026.

What Is Sodium Polystyrene Sulfonate?

Sodium Polystyrene Sulfonate belongs to a class of drugs called cation-exchange resins (also called potassium binders). It's been used for decades to treat hyperkalemia — a condition where potassium levels in the blood are too high.

Potassium is a mineral your body needs for normal heart, nerve, and muscle function. But when levels get too high (above 5.0 mEq/L), it can cause dangerous heart rhythm problems, muscle weakness, and in severe cases, cardiac arrest.

Sodium Polystyrene Sulfonate works in the gut — it's not absorbed into the bloodstream. It exchanges sodium ions for potassium ions in the intestines. The potassium-bound resin then passes out of your body in your stool. For a more detailed explanation, see how Sodium Polystyrene Sulfonate works.

What Is It Used For?

Sodium Polystyrene Sulfonate is FDA-approved for one primary use:

• Treatment of hyperkalemia — High blood potassium levels, typically in patients with chronic kidney disease (CKD), acute kidney injury, or other conditions that impair the body's ability to excrete potassium.

It is not used for:

• Preventing hyperkalemia (it's a treatment, not prevention)
• Routine potassium management in healthy people
• Emergency hyperkalemia treatment alone (IV calcium and insulin/glucose are used first in emergencies)

Most people who take Sodium Polystyrene Sulfonate have some form of kidney disease. If you've been prescribed it, your doctor has determined that your potassium levels need to come down.

How Is It Taken?

Sodium Polystyrene Sulfonate comes in three forms:

1. Oral Powder for Suspension

This is the most common form. You mix the powder with water or a non-potassium-containing liquid. Do not mix with orange juice, banana, or other potassium-rich foods or drinks. Do not heat the mixture.

2. Pre-Mixed Oral Suspension

A ready-to-take liquid form. This is convenient but has been subject to intermittent shortages.

3. Rectal Enema

Used when oral administration isn't possible (for example, if a patient is vomiting). The enema is retained in the colon for 30-60 minutes, then followed by irrigation.

Typical Dosage

The usual dose is 15 g to 60 g per day, taken as a single dose or divided into smaller doses throughout the day. Each 15 g dose binds approximately 15 mEq of potassium. Your doctor will determine the right dose based on your potassium levels and overall health.

Important Timing Rules

Sodium Polystyrene Sulfonate can interfere with other medications. Take other oral medications at least 3 hours before or after Sodium Polystyrene Sulfonate. For details on what to watch out for, see our drug interactions guide.

Who Should Not Take It?

Sodium Polystyrene Sulfonate is not safe for everyone. You should not take it if you have:

• Hypokalemia — If your potassium is already low, this medication would make it dangerously lower.
• Bowel obstruction — The resin could worsen a blocked intestine.
• Allergy to polystyrene sulfonate resins — Rare but possible.

It is also contraindicated in neonates (newborns) with reduced gut motility due to risk of intestinal necrosis.

Use with caution in:

• Elderly patients (higher risk of constipation and bowel problems)
• Patients taking digoxin (low potassium increases digoxin toxicity risk)
• Anyone with a history of bowel surgery or GI conditions

Always tell your doctor about your full medical history before starting this medication.

What Are the Side Effects?

Common side effects include nausea, vomiting, constipation, diarrhea, and stomach irritation. Serious but rare side effects include intestinal necrosis, bowel obstruction, and dangerous drops in potassium, calcium, or magnesium levels.

Read our full guide on Sodium Polystyrene Sulfonate side effects for details on what to watch for and when to call your doctor.

How Much Does It Cost?

Sodium Polystyrene Sulfonate is available as a generic medication, which keeps costs relatively low:

• Generic powder (454 g jar) — $6 to $50 without insurance, depending on the pharmacy.
• With a coupon — As low as $6-$20 at many pharmacies using GoodRx, SingleCare, or other discount cards.
• Brand-name Kayexalate — $47 to $100, though most patients use the generic.
• With insurance — Usually covered on Tier 1-2 formulary. Copays are typically low. Prior authorization is generally not required for generic SPS.

There are no manufacturer savings programs for Sodium Polystyrene Sulfonate, but the generic price is affordable for most patients. For more cost-saving tips, visit our savings guide.

Are There Alternatives?

If you can't take or find Sodium Polystyrene Sulfonate, two newer potassium binders are available:

• Patiromer (Veltassa) — A calcium-based binder with fewer GI side effects, but costs $600-$900/month.
• Sodium Zirconium Cyclosilicate (Lokelma) — A more selective potassium binder with faster onset, costing $500-$800/month.

These alternatives are significantly more expensive. Read our full comparison in alternatives to Sodium Polystyrene Sulfonate.

Final Thoughts

Sodium Polystyrene Sulfonate is a proven, affordable medication for treating high potassium levels. It's been used for decades and remains a first-line treatment for hyperkalemia, especially in patients with kidney disease.

If you've been prescribed it, make sure you understand how to take it properly, what side effects to watch for, and when to separate it from other medications. And if you're having trouble finding it at your pharmacy, use Medfinder to check stock near you — or explore our guide on how to find Sodium Polystyrene Sulfonate in stock.