Phosphate Salts

Phosphate Salts
Phosphate Salts


Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate. The effectiveness ratings for PHOSPHATE SALTS are as follows:

Effective for…

  • Preparing the bowel for a medical procedure. Taking sodium phosphate products by mouth before a colonoscopy procedure is effective for bowel cleansing. Some sodium phosphate products (OsmoPrep, Salix Pharmaceuticals; Visicol, Salix Pharmaceuticals) are approved by the US Food and Drug Administration (FDA) for this indication. However, taking sodium phosphate can increase the risk of kidney damage in some people. For this reason, sodium phosphate products are no longer commonly used in the U.S. for bowel preparation.
  • Low phosphate levels in the blood. Taking sodium or potassium phosphate by mouth is effective for preventing or treating low phosphate levels in the blood. Intravenous phosphate salts may also treat low phosphate levels in the blood when used under the supervision of a physician.

Likely effective for…

  • Constipation. Sodium phosphate is an FDA-permitted over-the-counter (OTC) ingredient for the treatment of constipation. These products are taken by mouth or used as enemas.
  • Indigestion. Aluminum phosphate and calcium phosphate are FDA-permitted ingredients used in antacids.
  • High calcium levels in the blood. Taking phosphate salt (except calcium phosphate) by mouth is likely effective for treating high levels of calcium in the blood. But intravenous phosphate salts should not be used.

Possibly effective for…

  • Kidney stones (nephrolithiasis). Taking potassium phosphate by mouth can help prevent calcium kidney stones from forming in patients with high urine levels of calcium.

Insufficient evidence to rate effectiveness for…

  • Athletic performance. Some early research shows that taking sodium phosphate by mouth for 6 days before high-intensity cycling or sprinting can improve athletic performance. But other early research shows no benefit. More studies are needed in larger groups of people to see if sodium phosphate is really beneficial. Taking other phosphate salts such as calcium phosphate or potassium phosphate doesn’t improve running or cycling performance.
  • Diabetes complication (diabetic ketoacidosis). Early research shows that giving potassium phosphate intravenously (by IV) does not improve a diabetes complication in which the body produces too many blood acids called ketones. People with this condition should only be given phosphates if they have low phosphate levels.
  • Osteoporosis. Research shows that taking calcium phosphate by mouth helps improve bone density of the hip and lower spine in women with osteoporosis. But it doesn’t work better than other sources of calcium, such as calcium carbonate.
  • Complications that occur upon eating in people who were previously starving (refeeding syndrome). Early research shows that giving sodium and potassium phosphate intravenously (by IV) over 24 hours prevents refeeding syndrome when restarting nutrition in people who are severely malnourished or starved.
  • Sensitive teeth.
  • Other conditions.

More evidence is needed to rate phosphate salts for these uses.

Side Effects Of Phosphate Salts

Phosphate salts containing sodium, potassium, aluminum, or calcium are LIKELY SAFE for most people when taken by mouth, inserted into the rectum, or given intravenously (by IV) appropriately and short-term. Phosphate salts should only be used intravenously (by IV) under the supervision of a physician.

Phosphate salts (expressed as phosphorous) are POSSIBLY UNSAFE when taken in doses higher than 4 grams per day for adults younger than 70 years of age and 3 grams per day for people who are older.

Regular long-term use can upset the balance of phosphates and other chemicals in the body and should be monitored by a healthcare professional to avoid serious side effects. Phosphate salts can irritate the digestive tract and cause stomach upset, diarrhea, constipation, headache, tiredness, and other problems.

Do not confuse phosphate salts with substances such as organophosphates, or with tribasic sodium phosphates and tribasic potassium phosphates, which are very poisonous.

Warnings & Precautions

  • Heart disease: Avoid using phosphate salts that contain sodium if you have heart disease.
  • Fluid retention (edema): Avoid using phosphate salts that contain sodium if you have cirrhosis, heart failure, or other conditions that can cause edema.
  • High levels of calcium in the blood (hypercalcemia): Use phosphate salts cautiously if you have hypercalcemia. Too much phosphate could cause calcium to be deposited where it shouldn’t be in your body.
  • High levels of phosphate in the blood: People with Addison’s disease, severe heart and lung disease, kidney disease, thyroid problems, or liver disease are more likely than other people to develop too much phosphate in their blood when they take phosphate salts. Use phosphate salts only with the advice and ongoing care of a healthcare professional if you have one of these conditions.
  • Kidney disease: Use phosphate salts only with the advice and ongoing care of a healthcare professional if you have kidney problems.

Dosage Of Phosphate Salts

The following doses have been studied in scientific research:


  • For raising phosphate levels that are too low: Healthcare providers measure the levels of phosphate and calcium in the blood and give just enough phosphate to correct the problem.
  • For lowering calcium levels that are too high: Healthcare providers measure the levels of phosphate and calcium in the blood and give just enough phosphate to correct the problem.
  • For preparing the bowel for a medical procedure: Three to four prescription tablets (OsmoPrep, Salix Pharmaceuticals; Visicol, Salix Pharmaceuticals) each containing 1.5 grams of sodium phosphate are taken with 8 ounces of water every 15 minutes for a total of 20 tablets the evening before colonoscopy. On the following morning, 3-4 tablets are taken with 8 ounces of water every 15 minutes until 12-20 tablets have been taken.
  • Kidney stones (nephrolithiasis): Potassium and sodium phosphate salts providing 1200-1500 mg of elemental phosphate daily have been used.
  • For raising phosphate levels that are too low: Intravenous (IV) products containing sodium phosphate or potassium phosphate have been used. Doses of 15-30 mmol have been given over 2-12 hours. Higher doses have been used if needed.
  • The recommended daily dietary allowances (RDAs) of phosphate (expressed as phosphorus) are Children 1-3 years, 460 mg; children 4-8 years, 500 mg; men and women 9-18 years, 1250 mg; men and women over 18 years, 700 mg.
  • The adequate intakes (AI) for infants are 100 mg for infants 0-6 months old and 275 mg for infants 7-12 months of age.

Tolerable Upper Intake Levels (UL), the highest intake level at which no unwanted side effects are expected, for phosphate (expressed as phosphorus) per day are: children 1-8 years, 3 grams per day; children and adults 9-70 years, 4 grams; adults older than 70 years, 3 grams; pregnant women 14-50 years, 3.5 grams; and breast-feeding women 14-50 years, 4 grams.


Consult your doctor or pharmacist.


All information has been provided courtesy of MedLinePlus from the National Library of Medicine and from the FDA.