Phosphorus is a naturally occurring substance that is important in every cell in the body. The majority of phosphorus in the body is found in the bones. The potassium and sodium salt forms of phosphorus are called phosphates.

Potassium phosphate and sodium phosphate is a combination medicine used to make the urine more acid to help prevent kidney stones.

Potassium phosphate and sodium phosphate may also be used for purposes not listed in this medication guide.

You should not take potassium phosphate and sodium phosphate if you are allergic to it, or if you have:

• severe kidney disease; or
• high levels of phosphorus in your blood (hyperphosphatemia).

To make sure this medicine is safe for you, tell your doctor if you have:

• a history of kidney stones in the distant past;
• kidney disease;
• cirrhosis or other liver disease;
• high blood levels of potassium (hyperkalemia), calcium (hypercalcemia), or sodium (hypernatremia);
• heart disease, high blood pressure;
• toxemia of pregnancy;
• Addison's disease (an adrenal gland disorder);
• breathing problems;
• pancreas disorder;
• thyroid disorder;
• swelling in your hands or feet;
• if you are dehydrated; or
• if you take a diuretic or "water pill."

FDA pregnancy category C. It is not known whether potassium phosphate and sodium phosphate will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant while using this medicine.

It is not known whether this medicine passes into breast milk or if it could harm a nursing baby. Tell your doctor if you are breast-feeding a baby.

Potassium phosphate and sodium phosphate should not be given to a child younger than 4 years old without a doctor's advice.

Use Phospho-Trin 250 Neutral (Oral) exactly as directed on the label, or as prescribed by your doctor. Do not use in larger or smaller amounts or for longer than recommended.

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have:

• severe or ongoing diarrhea;
• seizures (convulsion);
• shortness of breath; or
• signs of a kidney problem--little or no urinating; painful or difficult urination; swelling in your feet or ankles; feeling tired or short of breath.

Common side effects may include:

• nausea, vomiting, stomach pain, diarrhea;
• bone or joint pain;
• headache, dizziness, tired feeling;
• muscle pain or weakness;
• increased thirst; or
• numbness or tingly feeling.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Ask your doctor before using an antacid, and use only the type your doctor recommends. Some antacids can make it harder for your body to absorb potassium phosphate and sodium phosphate.

Avoid taking a vitamin or mineral supplement that contains calcium or vitamin D, unless your doctor tells you to.

Do not use potassium supplements or salt substitutes while you are taking potassium phosphate and sodium phosphate, unless your doctor has told you to.