Avoid if allergic to any ingredients in phosphorus/phosphate preparations.
In general, sodium, potassium, aluminum, and calcium phosphates are likely safe when used orally in recommended doses for short-term periods by people without hyperphosphatemia, impaired kidney function, or other health conditions known to increase the risk of hyperphosphatemia (see below). Sodium phosphate is likely safe when used rectally for short-term periods in otherwise healthy individuals with normal kidney function. Long-term use or high doses used orally or rectally require monitoring of serum electrolytes. Intravenous phosphate is likely safe when used as an FDA-approved prescription drug under medical supervision in people without hyperphosphatemia, impaired kidney function, or other health conditions known to increase the risk of hyperphosphatemia. Phosphate (expressed as phosphorus) intake taken via any route that exceeds the tolerable upper intake level (UL) is possibly unsafe, and may cause hyperphosphatemia (low phosphate levels), hypocalcemia (low calcium blood levels), calcification of nonskeletal tissues, and other electrolyte disturbances. Baseline electrolyte levels should be measured prior to starting phosphate therapy, including sodium, potassium, chloride, bicarbonate, calcium, phosphate, blood urea nitrogen (BUN), and creatinine. Sodium phosphate and potassium phosphate are cathartic agents, which can cause diarrhea.
Excessive intake of phosphates can cause potentially serious or life-threatening toxicity. Intravenous, oral, or rectal/enema phosphates may cause electrolyte disturbances including hypocalcemia (low calcium blood levels), hypomagnesemia (low magnesium blood levels), hyperphosphatemia (high phosphorus blood levels), or hypokalemia (low potassium levels). Calcification of non-skeletal tissues (particularly in the kidneys), severe hypotension (low blood pressure), dehydration, metabolic acidosis, acute kidney failure, or tetany can occur. Death has been reported in infants or adults with oral, rectal, or intravenous phosphates, particularly in those at increased risk for electrolyte disturbances. Late symptoms may include abdominal pain, vomiting of phosphorescent materials, bloody vomiting and diarrhea, headache, limb aches, tongue coating, foul breath, weakness, yellow conjunctivae (whites of the eyes). Rare complications may include confusion, convulsions (seizures), headache, dizziness, numbness, tingling, pain, weakness, anxiety, increased thirst, muscle cramps, or fatigue. Abnormal heart rhythms, shortness of breath, foot/leg swelling, and weight gain have been reported. Management of toxicity may include sulfate of copper emetic, or lavage with Epsom salts in water (repeated every hour); repeated small doses of sulfate of copper and large doses of bicarbonate of soda. Oxygen inhalation, external heat, camphor, old oil of turpentine, and permanganate of potassium have been recommended.
Sodium phosphate and potassium phosphate are cathartic agents, and may cause diarrhea. Nausea, vomiting, or gastrointestinal irritation can occur. A reduction in dosage may be necessary to minimize diarrhea. Potassium acid phosphate may cause dyspepsia in patients with a history of peptic ulcer disease. Aluminum phosphate can cause constipation.
Conditions which may be worsened with excessive phosphorus/phosphate supplementation include burns, heart disease, pancreatitis, rickets, osteomalacia (softening of bones), underactive parathyroid glands (with sodium phosphate or potassium phosphate), dehydration, underactive adrenal glands (potassium phosphate may increase the risk of hyperkalemia), edema, high blood pressure, liver disease, toxemia of pregnancy, hyperphosphatemia, kidney disease.
U.S. Food and Drug Administration Pregnancy Category: C.
The Tolerable Upper Intake Level (UL) for phosphorus in pregnant women is 3.5 grams per day, and in breastfeeding women is 4 grams per day.
Adults (18 years and older)
The National Academy of Sciences has recommended 700 milligrams of phosphorus per day in adults ages 18 years and older, including pregnant or breastfeeding women.
The Tolerable Upper Intake Level (UL) for adults ages 19-70 years-old is 4 grams per day; for adults 70 years and older the UL is 3 grams per day. The recommended UL in pregnant women is 3.5 grams per day, and in breastfeeding women is 4 grams per day. Phosphate salts should not be administered to patients with hyperphosphatemia, and should be used cautiously in those with impaired kidney function.
Doses typically range from 1-3 grams of phosphorous (as a phosphate salt (sodium phosphate or potassium phosphate) or elemental phosphate) per day by mouth for the treatment of calcium oxalate kidney stones, hypercalcemia, or hypophosphatemia. Doses are usually divided and taken throughout the day.
Fleet Enema (118 milliliters) can be used as a laxative when administered rectally. It should be administered as a single daily dose. Laxatives should not generally be used for more than one week. 4-8 grams of sodium phosphate dissolved in water has also been used as a saline laxative (should be taken with plenty of water).
Intravenous phosphate 50 millimoles (sodium 81 millimoles, potassium 9.5 millimoles) over 24 hours has been used during refeedng syndrome when serum phosphate falls below 0.5 millimoles per liter. Phosphate blood levels should be closely followed.
Children (younger than 18 years)
The recommended adequate intake in infants 0-6 months-old is 100 milligrams per day (additional phosphorus may be added to infant formulas); the recommended adequate intake in infants 7-12 months old is 275 milligrams per day; the recommended daily intake in children ages 1-3 years-old is 460 milligrams per day; the recommended daily intake in children ages 4-8 years-old is 500 milligrams per day; the recommended daily intake in children ages 9-18 years-old is 1,250 milligrams per day (including pregnant or breastfeeding females).
The Tolerable Upper Intake Level (UL) for infants aged 0-12 months-old is not clearly established and the source of intake should be from food and formula only; for children 1-8 years-old the UL is 3 grams per day; for children 9-18 years-old the UL is 4 grams per day.
Children under 12 years of age should not receive an adult size Fleet enema. Children 2 to 12 years of age may receive a Fleet Ready-To-Use Enema for children in a single daily dose (2 fluid ounces). Laxatives should not generally be used for more than one week.
Children 5 to 10 years-old may receive 5 milliliters Fleet Phospho-soda and should not exceed 10 milliliters in a 24-hour period. Children between 10 to 12 years-old may receive 10 milliliters and should not exceed 20 milliliters in a 24-hour period. Children over 12 years-old may receive a dose of 20 milliliters and should not exceed 45 milliliters in a 24-hour period. Do not administer to children under 5 years of age.
Children may also receive intravenous preparations, which should be given under the supervision of a licensed healthcare professional.
Interactions with Drugs
Antacids containing aluminum, calcium, or magnesium can bind phosphate in the gut and prevent its absorption, potentially leading to hypophosphatemia (low phosphate levels) when used chronically.
Some anticonvulsants (including phenobarbital and carbamazepine) may lower phosphorus levels and increase levels of alkaline phosphatase.
Bile acid sequestrants such as cholestyramine (Questran®) and colestipol (Colestid®) can decrease oral absorption of phosphate. Therefore, oral phosphate supplements should be administered at least one hour before or four hours after these agents.
Corticosteroids may increase urinary phosphorus levels.
Potassium supplements or potassium-sparing diuretics taken together with a phosphate may result in high blood levels of potassium (hyperkalemia).
Alcohol (ethanol) may increase urinary phosphorus. Wine may enhance absorption of phosphorus (as well as calcium and magnesium).
Medications that may affect electrolyte levels should be used cautiously with phosphates. Examples include: amiloride (Midamor®); angiotensin-converting enzyme (ACE) inhibitors such as benazepril (Lotensin), captopril (Capoten®), enalapril (Vasotec®), fosinopril (Monopril®), lisinopril (Zestril®, Prinivil®), quinapril (Accupril®), or ramipril (Altace®); cyclosporine; cardiac glycosides (Digoxin®); heparins; anti-inflammatory drugs; potassium-containing agents; salt substitutes; spironolactone (Aldactone®); and triamterene (Dyrenium®).
Calcium may impair phosphates in the body, and result in calcium deposits in tissues.
Pumpkin seed may increase urine phosphates.
Excessive doses of calcitriol, the active form of vitamin D (or its analogs) may result in hyperphosphatemia (high phosphate levels).