PhosLo (calcium acetate): what it does and how to use it safely
PhosLo is a prescription medicine doctors use to lower high phosphate in people with chronic kidney disease. High phosphate can damage blood vessels and bones. PhosLo binds phosphate from food inside your gut so your body passes it in stool instead of keeping it in the blood.
Most people take PhosLo with meals. That timing matters: phosphate from food appears during digestion, so taking the pill with food lets it bind the phosphate right away. Doses vary, usually one to two tablets with each meal, but follow your doctor's instructions. Never double a missed dose; wait until your next meal and take the prescribed amount.
Common side effects and warnings
Stomach upset, constipation, or nausea are the most reported side effects. If you get severe constipation, black stool, or stomach pain, call your doctor. PhosLo raises calcium levels in some people, which can cause weakness, confusion, or irregular heartbeat. Your healthcare team will check blood calcium and phosphate often while you take PhosLo.
Don't use PhosLo if you have high blood calcium or certain conditions that cause calcium buildup. Tell your doctor about all medicines you take. Calcium-containing antacids, vitamin D supplements, or other phosphate binders can change how PhosLo works. Your provider may change doses to keep calcium and phosphate balanced.
Practical tips for everyday use
Take PhosLo exactly with meals as prescribed. If you eat snacks that contain phosphate, treat them like a meal and take PhosLo with the snack. Avoid taking PhosLo at the same time as oral iron, levothyroxine, or certain antibiotics like fluoroquinolones and tetracyclines; separate them by at least two hours to prevent reduced absorption.
Keep a food diary for a week to spot high-phosphate foods you might not expect, like cola, processed cheeses, and cured meats. Working with a renal dietitian can make low-phosphate eating easier and help reduce the number of pills you need. Stay hydrated unless your doctor tells you otherwise.
If you are on dialysis, your doctor may adjust PhosLo based on dialysis schedule and recent labs. Do not stop PhosLo just because numbers look better once — kidney-related mineral balance can change quickly. Store tablets at room temperature away from moisture and keep them out of reach of children. Always review over-the-counter supplements with your clinic; many contain hidden phosphate or calcium that affect treatment. Bring a current medication list to each appointment and ask about dose changes.
Pregnant or breastfeeding people should discuss risks and benefits with their provider. Also tell your team if you have parathyroid disease, heart issues, or high blood calcium. If you experience allergic signs — hives, swelling, difficulty breathing — seek emergency care.
PhosLo helps many people control phosphate when kidneys can’t. It works best as part of a plan: diet changes, regular lab checks, and clear communication with your healthcare team. Ask your doctor how often to test calcium and phosphate and whether PhosLo fits your other meds and meals.
PhosLo Uses, Side Effects, and Tips for Kidney Health
Everything you need to know about PhosLo: its uses, side effects, and tips on managing phosphate levels for kidney disease and dialysis patients.
20.06.25
Alistair Mukondiwa
11