Calcium Acetate

1 medicine

Calcium acetate is a phosphate binder for high phosphate in chronic kidney disease and dialysis, not a calcium or bone supplement. It only works when taken with meals, and overuse can raise blood calcium to dangerous levels.

Phoslo

Calcium acetate

667mg

Phoslo is a bone support medication containing Calcium acetate, available as 667mg tablets.

from $0.51 / tablet View

Key facts

  • Calcium acetate is a phosphate binder, not a calcium supplement. It's used in chronic kidney disease and dialysis to stop dietary phosphate from being absorbed.
  • Take it with meals or immediately after eating; without food in your gut it has nothing to bind and won't lower your phosphate.
  • Taking more than prescribed, or combining it with other calcium or vitamin D products, can push your blood calcium too high, a real risk given that calcium acetate is itself a calcium salt.
  • Seek care for confusion, irregular heartbeat, or severe muscle weakness, which can signal high blood calcium.

What calcium acetate treats

Calcium acetate treats hyperphosphatemia, high blood phosphate that builds up when failing kidneys can no longer clear it, most often in people with advanced chronic kidney disease or on dialysis. Lowering phosphate this way helps protect bones and blood vessels from the damage that long-term high phosphate causes. It does not treat low calcium or osteoporosis, and it is not a general bone-health supplement.

How calcium acetate works

As food moves through your gut, calcium acetate binds to phosphate from that food, forming a compound your intestine cannot absorb, so the phosphate leaves the body in stool instead of entering the bloodstream. Because this binding only happens when the drug and dietary phosphate are in the gut together, timing it with meals is what makes it work.

Before you take it

  • Do not take calcium acetate if you already have high blood calcium.
  • Tell your care team about any other calcium, vitamin D, or antacid products you take, since these add to your total calcium load.
  • Mention a history of kidney stones or heart disease, which may need extra monitoring.
  • If you're pregnant or breastfeeding, confirm the dose with your care team rather than adjusting it yourself.

Side effects

Common effects include constipation, nausea, gas, or bloating, especially when starting treatment.

Stop and seek urgent medical care for any of these:

  • Confusion, irregular heartbeat, or severe fatigue, which can signal high blood calcium.
  • Severe or persistent stomach pain.
  • Vomiting or diarrhea that leads to dehydration.

Safety essentials

  • Always take it with food. Calcium acetate taken on an empty stomach doesn't bind phosphate and only adds calcium you don't need.
  • Your care team will check your blood calcium and phosphate regularly. Dose changes are based on these results, not on how you feel.
  • Do not add other calcium or vitamin D supplements without checking first, since calcium acetate already contributes calcium on top of your diet.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.