What Is Calcium Acetate? Uses, Dosage, and What You Need to Know in 2026

Calcium acetate is a prescription medication used to treat high phosphate levels in people with kidney failure who are on dialysis. It is sold under the brand names PhosLo, Phoslyra, Eliphos, and Calphron. This guide covers everything you need to know about calcium acetate — what it does, how to take it, possible side effects, and important safety information.

What Is Calcium Acetate Used For?

Calcium acetate is FDA-approved to treat hyperphosphatemia — high levels of phosphate in the blood — in patients with end-stage renal disease (ESRD) who are on dialysis. The FDA first approved calcium acetate in December 1990.

When the kidneys fail, they can no longer filter excess phosphate from the blood. Phosphate comes primarily from the foods we eat — especially protein-rich foods, dairy, nuts, and beans. In healthy people, the kidneys excrete excess phosphate efficiently. In dialysis patients, phosphate builds up in the blood between dialysis sessions, which can cause serious complications including weak bones, calcification of blood vessels, and an overactive parathyroid gland (secondary hyperparathyroidism).

What Drug Class Is Calcium Acetate?

Calcium acetate belongs to a class of drugs called phosphate binders. These medications work by binding to phosphate in the food you eat, preventing it from being absorbed into your bloodstream. The phosphate then exits the body in your stool. By reducing phosphate absorption, calcium acetate helps keep blood phosphate levels within a safe range.

What Forms Does Calcium Acetate Come In?

Calcium acetate is available in three forms, all at a strength of 667 mg per unit:

Capsule (667 mg): The most commonly prescribed form. Brand names include PhosLo Gelcap.

Tablet (667 mg): Available under the Eliphos brand name and as a generic.

Oral solution / liquid (667 mg per 5 mL): Sold as Phoslyra. Prescribed for patients who cannot swallow capsules or tablets.

How Is Calcium Acetate Taken?

Calcium acetate must be taken with every meal. This is essential — if you take it without food, it cannot bind to dietary phosphate and will not work properly. Most patients take it at the very start of their meal with the first few bites.

The typical starting dose is 2 tablets or capsules (1334 mg) per meal, or 10 mL of the liquid. Your nephrologist will adjust this over several weeks based on your blood phosphate test results. Most patients end up taking 3–4 tablets or capsules (2001–2668 mg) per meal as their maintenance dose.

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Is Calcium Acetate a Controlled Substance?

No. Calcium acetate is not a controlled substance. It has no abuse potential and is not assigned a DEA schedule. It requires a prescription, but it can be prescribed by any licensed physician, NP, or PA without special restrictions.

Important Safety Information

Here are the most important safety points every calcium acetate patient should know:

Do not take extra calcium supplements or calcium-containing antacids (like Tums) while on calcium acetate without your doctor's approval. The combined calcium load increases the risk of hypercalcemia.

Separate from antibiotics: Take fluoroquinolones (ciprofloxacin, levofloxacin) at least 2 hours before or 6 hours after calcium acetate. Take tetracyclines (doxycycline, minocycline) at least 1 hour before.

Separate from thyroid medication: Take levothyroxine (Synthroid) at least 4 hours before or after calcium acetate.

Tell your doctor about digoxin: High calcium levels increase digoxin toxicity risk. Your provider should monitor digoxin levels closely if you take both medications.

Get regular blood tests: Your nephrologist will check serum calcium and phosphate levels regularly to make sure calcium acetate is working and not causing hypercalcemia.

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Who Should Not Take Calcium Acetate?

Calcium acetate should NOT be taken by patients who:

Already have high calcium levels in their blood (hypercalcemia)

Are allergic to calcium acetate or any of its ingredients

Are under 18 years old (not FDA-approved for pediatric use)

Finding Calcium Acetate and Getting Started

If you are having trouble finding calcium acetate in stock, medfinder is a paid service that contacts pharmacies near you to locate your medication. Want to understand more about how calcium acetate works in the body? Read our deep dive on how calcium acetate works.