What is it?
People use phosphate salts for medicine. Be careful not to confuse phosphate salts with substances such as organophosphates, or with tribasic sodium phosphates and tribasic potassium phosphates, which are very poisonous.
Phosphate salts are taken by mouth for treating blood phosphate levels that are too low and blood calcium levels that are too high, and for preventing kidney stones. They are also taken for treating osteomalacia (often called “rickets” in children), a condition caused by a mineral imbalance in the body that leads to softening of the bones. Phosphate salts are also used for improving exercise performance, as an antacid for gastroesophageal reflux disease (GERD), and as a laxative for emptying the bowels before surgery.
Phosphate salts and calcium are applied to sensitive teeth to reduce pain.
Rectally, phosphate salts are used as a laxative to clean the bowels before surgery or intestinal tests.
Healthcare providers sometimes give potassium phosphate intravenously (by IV) for treating low phosphate and high calcium levels in the blood, and for preventing low phosphate in patients who are being tube-fed.
How effective is it?
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:
- Preparing the bowel for a medical procedure. Sodium phosphate tablets (OsmoPrep, Visicol, Salix Pharmaceuticals, Raleigh, NC) are FDA-approved for cleansing the colon before a colonoscopy. Over-the-counter sodium phosphate solutions and enemas may also be used for bowel cleansing before medical procedures.
- 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 might help prevent calcium kidney stones from forming in patients with high urine levels of calcium.
Possibly ineffective for...
- Athletic performance. Some early research suggests that taking sodium phosphate by mouth four times daily for 6 days might increase athletic performance in male cyclists. However, most evidence shows that taking phosphate salts by mouth does not improve exercise performance.
Insufficient evidence to rate effectiveness for...
- Diabetes complication (diabetic ketoacidosis). Early research suggests that taking 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.
- Complications that occur upon eating in people who were previously starving (refeeding syndrome). Limited research shows that giving sodium and potassium phosphates intravenously (by IV) over 24 hours prevents refeeding syndrome when restarting nutrition in people who are severely malnourished or starved.
- Sensitive teeth.
- Other conditions.
How does it work?
Are there safety concerns?
Phosphate (expressed as phosphorus) is POSSIBLY UNSAFE when taken in amounts 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, 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.
Special precautions & warnings:Pregnancy and breast-feeding: Phosphate salts from dietary sources are LIKELY SAFE for pregnant or breast-feeding women when used at the recommended allowances of 1250 mg daily for mothers between 14-18 years of age and 700 mg daily for those over 18 years of age. Other amounts are POSSIBLY UNSAFE and should only be used with the advice and ongoing care of a healthcare professional.
Children: Phosphate salts are LIKELY SAFE for children when used at the recommended daily allowances of 460 mg for children 1-3 years of age; 500 mg for children 4-8 years of age; and 1250 mg for children 9-18 years of age. Phosphate salts are POSSIBLY UNSAFE if the amount of phosphate consumed (expressed as phosphorous) exceeds the tolerable upper intake level (UL). The ULs are 3 grams per day for children 1-8 years; and 4 grams per day for children 9 years and older.
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.
Are there interactions with medications?
- Bisphosphonate medications and phosphate salts can both lower calcium levels in the body. Taking large amounts of phosphate salts along with bisphosphonate medications might cause calcium levels to become too low.
Some bisphosphonates include alendronate (Fosamax), etidronate (Didronel), risedronate (Actonel), tiludronate (Skelid), and others.
Are there interactions with herbs and supplements?
- Phosphate can combine with calcium. This reduces the body's ability to absorb phosphate and calcium. To avoid this interaction, phosphate should be taken at least 2 hours before or after taking calcium.
- Phosphate can combine with iron. This reduces the body's ability to absorb phosphate and iron. To avoid this interaction, phosphate should be taken at least 2 hours before or after taking iron.
- Phosphate can combine with magnesium. This reduces the body's ability to absorb phosphate and magnesium. To avoid this interaction, phosphate should be taken at least 2 hours before or after taking magnesium.
- Niacin might affect phosphate levels in the body. Taking slow-release niacin (Niaspan, Abbott Labs) by mouth daily for 8 weeks appears to reduce phosphate levels by about 15%.
Are there interactions with foods?
- Phosphate-containing foods and drinks
- In theory, taking phosphate with phosphate-containing foods and drinks might increase phosphate levels and increase the risk of side effects, especially in people with kidney problems. Phosphate-containing foods and beverages include cola, wine, beer, whole grain cereals, nuts, dairy products and some meats.
What dose is used?
- For raising phosphate levels that are too low or 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.
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.
To learn more about how this article was written, please see the Natural Medicines Comprehensive Database methodology.
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