Health & Well-Being A-Z

Phosphate Salts

3D illustration of Phosphorus Element

Phosphorus is an essential mineral found in many foods. In the diet and body, phosphorus usually binds to other minerals in the form of phosphate salts.

Phosphates are involved in cell structure, energy transport and storage, vitamin function, and many other essential processes in the body. Phosphate salts can act as laxatives by causing more fluid to be drawn into the intestines and making the gut push out its contents faster.

People use phosphate salts for bowel cleansing, low blood levels of phosphate, constipation, high blood levels of calcium, and heartburn. They are also used for athletic performance, osteoporosis, and many other conditions, but there is no good scientific evidence to support these other uses.

Is It Effective?

Effectiveness header

NatMed Pro 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.

  • Emptying the colon before a colonoscopy. Taking sodium phosphate products by mouth before a colonoscopy is effective for bowel cleansing. Some sodium phosphate products are approved by the US FDA for this use. But taking sodium phosphate can increase the risk of kidney damage in some people and should be used with caution.
  • Low levels of phosphate in the blood (hypophosphatemia). Taking sodium or potassium phosphate by mouth or by IV is effective for preventing or treating low phosphate levels in the blood. IV products can only be given by a healthcare provider.
Likely effective
  • Constipation. Sodium phosphate is an FDA-approved over-the-counter (OTC) ingredient for treating constipation. OTC products are taken by mouth or used as enemas.
  • Indigestion (dyspepsia). Aluminum phosphate and calcium phosphate are FDA-approved ingredients in OTC antacids.
  • High levels of calcium in the blood (hypercalcemia). Taking phosphate salts by mouth is likely effective for treating high levels of calcium in the blood. But calcium phosphate should not be used since it contains calcium and can increase calcium levels.
Possibly effective
  • Kidney stones. Taking potassium phosphate by mouth can help prevent calcium kidney stones from forming in people with high urine levels of calcium.

There is interest in using phosphate salts for a number of other purposes, but there isn't enough reliable information to say whether it might be helpful.

Is it Safe?


When taken by mouth: Phosphate salts are likely safe when consumed in the diet, or when supplements are used appropriately for a short time. Phosphate salts might cause side effects such as stomach upset, diarrhea, headache, and others.

Phosphate salts (as phosphorous) are possibly unsafe when taken in doses higher than 4 grams daily for adults 70 years and younger, or in doses higher than 3 grams daily for people over 70 years. 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.

When given as an enema (rectally): Phosphate salts are likely safe for most people when inserted into the rectum appropriately and short-term. But these products shouldn't be used more than once daily.

Special Precautions & Warnings:

Pregnancy and breast-feeding: Phosphate salts are commonly consumed in the diet. Phosphate salts are possibly unsafe when taken in amounts above the tolerable upper intake level (UL). The UL is 3.5 grams daily during pregnancy and 4 grams daily while breast-feeding.

Children: Phosphate salts are commonly consumed in the diet. Phosphate salts are possibly unsafe when taken in amounts that exceed the tolerable upper intake level (UL). The UL is 3 grams daily for children 1-8 years old and 4 grams daily for children 9 years and older.

Giving a sodium phosphate enema to children OVER 2 years of age is likely safe when no more than one dose is given every 24 hours. But it is likely unsafe to give more than one dose every 24 hours, or to give a sodium phosphate enema to children who are under 2 years of age.

Gastrointestinal (GI) conditions:: Sodium phosphate can cause damage to the intestines in some people. If you have an obstruction or have an inflammatory GI condition, avoid using sodium phosphate.

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 to have too much phosphate in their blood when they take phosphate salts. Use phosphate salts only while under the care of a healthcare professional if you have one of these conditions.

Kidney disease: Use phosphate salts only while under the care of a healthcare professional if you have kidney problems.

Drug interactions


Interaction Rating=Moderate Be cautious with this combination.

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.

Erdafitinib (Balversa)

Interaction Rating=Major Do not take this combination.

Erdafitinib increases the amount of phosphate in the blood. Taking phosphate salts along with erdafitinib can cause very high phosphate levels and serious side effects. Avoid phosphates when using erdafitinib.

Herb interactions

Calcium: Phosphate can bind 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.
Iron: Phosphate can bind 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.
Magnesium: Phosphate can bind 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.

Food interactions

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.


Phosphate (as phosphorus) is found in many foods, including meat, fish, eggs, and dairy products. Phosphate deficiencies are rare. The amount that should be consumed on a daily basis is called the recommended dietary allowance (RDA). For adults, the RDA is 700 mg. While pregnant or breast-feeding, the RDA is 1250 mg for those 14-18 years of age and 700 mg for those over 18 years of age. In children, the RDA depends on age. Speak with a healthcare provider to find out what type of product and dose might be best for a specific condition.

Other names

Aluminum phosphate, Bone Phosphate, Calcium phosphate, Calcium Orthophosphate, Calcium Phosphate Dibasic Anhydrous, Calcium Phosphate-Bone Ash, Calcium Phosphate Dibasic Dihydrate, Calcium Phosphate Dibasique Anhydre, Calcium Phosphate Dibasique Dihydrate, Calcium Phosphate Tribasic, Calcium Phosphate Tribasique, Dibasic Calcium Phosphate Dihydrate, Di-Calcium Phosphate, Dicalcium Phosphate, Dicalcium Phosphates, Neutral Calcium Phosphate, Orthophosphate de Calcium, Phosphate d'Aluminium, Phosphate de Calcium, Phosphate de Magnésium, Phosphate Neutre de Calcium, Phosphate d'Os, Phosphate Tricalcium, Precipitated Calcium Phosphate, Précipitation du Phosphate de Calcium, Précipité de Phosphate de Calcium, Tertiary Calcium Phosphate, Tricalcium Phosphate, Whitlockite, Magnesium Phosphate, Merisier, Potassium phosphate, Dibasic Potassium Phosphate, Dipotassium Hydrogen Orthophosphate, Dipotassium Monophosphate, Dipotassium Phosphate, Monobasic Potassium Phosphate, Potassium Acid Phosphate, Potassium Biphosphate, Potassium Dihydrogen Orthophosphate, Potassium Hydrogen Phosphate, Phosphate de Dipotassium, Phosphate d'Hydrogène de Potassium, Phosphate de Potassium, Phosphate de Potassium Dibasique, Phosphate de Potassium Monobasique, Sodium phosphate, Anhydrous Sodium Phosphate, Dibasic Sodium Phosphate, Disodium Hydrogen Orthophosphate, Disodium Hydrogen Orthophosphate Dodecahydrate, Disodium Hydrogen Phosphate, Disodium Phosphate, Phosphate of Soda, Sales de Fosfato, Sels de Phosphate, Sodium Orthophosphate, Orthophosphate Disodique d'Hydrogène, Phosphate Disodique d'Hydrogène, Orthophosphate de Sodium, Phosphate de Sodium Anhydre, Phosphate de Sodium Dibasique, Phosphorus.


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