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Sodium Phosphate

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Sodium phosphate can cause serious kidney damage and possibly death. In some cases, this damage was permanent, and some people whose kidneys were damaged had to be treated with dialysis (treatment to remove waste from the blood when the kidneys are not working well). Some people developed kidney damage within a few days after their treatment, and others developed kidney damage up to several months after their treatment. Tell your doctor if you have ever had a biopsy (removal of a piece of tissue for examination in a laboratory) that showed that you have kidney problems caused by too much phosphate or stomach surgery and if you have or have ever had a blockage or tear in your intestine. Your doctor may tell you not to take sodium phosphate. Also tell your doctor if you are constipated, you have severe stomach pain or bloating, you think you may be dehydrated (have lost a lot of fluid from your body), or you have or develop symptoms of dehydration such as vomiting, dizziness, decreased urination, and headache. Tell your doctor if you have or have ever had a low level of calcium, sodium, magnesium, or potassium in your blood; a high level of sodium or phosphate in your blood; colitis (inflammation of the large intestine) or other conditions that irritate your intestine; slow moving bowels; heart failure (condition in which the heart cannot pump blood through the body as well as it should); or kidney disease. Also tell your doctor and pharmacist if you are taking angiotensin converting enzyme inhibitors (ACEIs) such as benazepril (Lotensin, in Lotrel), captopril, enalapril (Epanid, Vasotec, in Vaseretic), fosinopril, lisinopril (Prinivil, Qbrelis, Zestril, in Zestoretic), moexipril, perindopril (Aceon, in Prestalia), quinapril (Accupril, in Accuretic and Quinaretic), ramipril (Altace), or trandolapril (in Tarka); angiotensin receptor blockers (ARBs) such as candesartan (Atacand, in Atacand HCT), eprosartan (Teveten), irbesartan (Avapro, in Avalide), losartan (Cozaar, in Hyzaar), olmesartan (Benicar, in Azor and Tribenzor), telmisartan (Micardis, in Micardis HCT and Twynsta), or valsartan (Diovan, in Byvalson, Diovan HCT, Entresto, Exforge, and Exforge HCT); aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen (Advil, Motrin, others) and naproxen (Aleve, Naprosyn, others); or diuretics (water pills). The risk that you may develop kidney damage is higher if you have any of these conditions, are taking any of these medications, or are older than 55 years old. However, you may develop kidney damage even if you do not have any of these conditions, are not taking any of these medications, and are younger than 55 years old. If you experience any of the following symptoms, call your doctor immediately: weakness, drowsiness, decreased urination, or swelling of the ankles, feet, or legs.

It is very important that you drink plenty of clear liquids during and after your treatment with sodium phosphate. You should not take any other laxatives or use any enemas while you are taking this medication.

Keep all appointments with your doctor and the laboratory. Your doctor may order certain tests to check your body’s response to sodium phosphate.

Your doctor or pharmacist will give you the manufacturer’s patient information sheet (Medication Guide) when you begin treatment with sodium phosphate. Read the information carefully and ask your doctor or pharmacist if you have any questions. You can also visit the Food and Drug Administration (FDA) website ( or the manufacturer’s website to obtain the Medication Guide.

Talk to your doctor about the risks of taking sodium phosphate.

Why is this medication prescribed?

Sodium phosphate is used in adults 18 years of age or older to empty the colon (large intestine, bowel) before a colonoscopy (examination of the inside of the colon to check for colon cancer and other abnormalities) so that the doctor will have a clear view of the walls of the colon. Sodium phosphate is in a class of medications called saline laxatives. It works by causing diarrhea so that the stool can be emptied from the colon.

How should this medicine be used?

Sodium phosphate comes as a tablet to take by mouth. It is usually taken as one dose the night before a colonoscopy is scheduled and one dose the following morning (3 to 5 hours before the procedure). For each dose, your doctor will tell you to take a certain number of tablets with 8 ounces of clear liquid, wait 15 minutes, and then take more tablets with 8 ounces of clear liquid. You will repeat this several more times until you have taken all the tablets that your doctor prescribed for that dose.

It is very important that you drink the full amount of clear liquid with each dose of sodium phosphate, and that you drink plenty of clear liquid at other times before, during, and after your treatment with sodium phosphate. Examples of clear liquids are water, clear flavored broth, herbal or black tea, black coffee, flavored water, lemonade or limeade without pulp, apple or white grape juice, gelatin, popsicles, and clear soda (ginger ale). Do not drink alcohol, milk, or any liquids that are colored purple or red. Tell your doctor if you have trouble drinking clear liquids.

Other uses for this medicine

This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.

What special precautions should I follow?

Before taking sodium phosphate,

  • Tell your doctor and pharmacist if you are allergic to sodium phosphate, other medications, or any of the ingredients in the tablets. Check the prescription label or ask your pharmacist for a list of the ingredients.
  • Tell your doctor if you have already taken sodium phosphate or used an enema containing sodium phosphate within the past 7 days. You should not take sodium phosphate more than once in 7 days.
  • Tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Be sure to mention the medications listed in the IMPORTANT WARNING section and any of the following: alprazolam (Xanax), amiodarone (Cordarone, Pacerone); amitriptyline, desipramine (Norpramin), diazepam (Diastat, Valium), disopyramide (Norpace), dofetilide (Tikosyn), erythromycin (E.E.S., Erythrocin), estazolam, flurazepam, lorazepam (Ativan), medications for seizures, midazolam (Versed) moxifloxacin (Avelox), pimozide (Orap), quinidine (Quinidex, in Nuedexta), sotalol (Betapace, Betapace AF, Sorine), thioridazine, or triazolam (Halcion). Your doctor may need to change the doses of your medications or monitor you carefully for side effects. Many other medications may also interact with sodium phosphate, so be sure to tell your doctor about all the medications you are taking, even those that do not appear on this list.
  • If you are taking any other medications by mouth, talk to your doctor about when you should take them during your treatment with sodium phosphate. Medications that you take 1 hour before you take sodium phosphate may not be absorbed properly.
  • Tell your doctor if you follow a low salt diet, if you had been drinking large amounts of alcohol or taking medications for anxiety or seizures and are now gradually decreasing your use of these substances, and if you have had heart surgery. Also tell your doctor if you have or have ever had a prolonged QT interval (a rare heart problem that may cause irregular heartbeat, fainting, or sudden death), an irregular heartbeat, a heart attack, chest pain, seizures, inflammatory bowel disease (IBD; a group of conditions in which all or part of the lining of the intestine is swollen, irritated, or has sores) difficulty swallowing.
  • Tell your doctor if you are pregnant, plan to become pregnant, or are breastfeeding.

What special dietary instructions should I follow?

Your doctor will tell you what you may eat and drink before, during, and after your treatment with sodium phosphate. Follow these directions carefully.

What should I do if I forget a dose?

Call your doctor if you forget or are unable to take sodium phosphate exactly as directed.

What side effects can this medication cause?

Sodium phosphate may cause side effects. Tell your doctor if either of these symptoms is severe or do not go away:

  • Stomach pain
  • Nausea
  • Bloating

Some side effects can be serious. If you experience any of these symptoms or those listed in the IMPORTANT WARNING section, call your doctor immediately:

  • Irregular heartbeat
  • Vomiting
  • Fainting
  • Seizures
  • Rash
  • Hives
  • Itching
  • Swelling of the eyes, face, lips, tongue, mouth or throat
  • Burning or tingling of the lips, tongue, or mouth
  • Throat tightness
  • Difficulty breathing or swallowing

Sodium phosphate may cause other side effects. Call your doctor if you have any unusual problems while you are taking this medication.

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration’s (FDA) MedWatch Adverse Event Reporting program online ( or by phone (1-800-332-1088).

What should I know about storage and disposal of this medication?

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom).

Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA’s Safe Disposal of Medicines website ( for more information if you do not have access to a take-back program.

It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach.

In case of emergency/overdose

In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at If the victim has collapsed, had a seizure, has trouble breathing, or can’t be awakened, immediately call emergency services at 911.

Symptoms of overdose may include the following:

  • Seizures
  • Irregular heartbeat
  • Vomiting
  • Dizziness
  • Headache
  • Decreased urination

What other information should I know?

Do not let anyone else take your medication. Your prescription is probably not refillable, since you will not need more sodium phosphate after your colonoscopy.

Sodium phosphate has also been sold as a nonprescription laxative to relieve constipation. Many nonprescription oral sodium phosphate products are no longer sold in the United States, but some may still be available. If you are taking oral sodium phosphate for constipation, it is important that you take it exactly as directed on the package label. Do not take more of the medication than directed on the label for each dose, and do not take more than one dose in 24 hours even if you do not have a bowel movement after you take the medication. Do not give nonprescription oral sodium phosphate to a child 5 years of age or younger unless the child’s doctor tells you that you can. Taking too much nonprescription sodium phosphate may cause serious damage to the heart or kidneys or death.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.

Brand names

  • OsmoPrep,®
  • Visicol®
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