Sodium Phosphate Dibasic and Sodium Phosphate Monobasic (Oral)

Sodium phosphate dibasic and sodium phosphate monobasic is a combination of medicines used before a colonoscopy in order to empty the bowels.


The combination of Sodium phosphate dibasic and sodium phosphate monobasic is a laxative used in patients to trigger an emptying of the bowels. This medicine triggers diarrhea so that the colon can be cleared. The treatment is used before a colonoscopy so that the doctor can examine the inside of your colon without obstruction.

This medication is only available with a prescription from your doctor and can be taken in liquid, tablet or solution forms.

Sodium phosphate dibasic and sodium phosphate monobasic combination is available in the following brands:

  • Visicol
  • Phospho-Soda
  • OsmoPrep
  • Fleet Phospho-soda EZ-Prep

This medication should be taken over a period of time with regular consumption of water interspersed with the doses. The treatment is to be used in the evening before a colonoscopy.

Use of this medication poses a real risk of causing kidney problems. You should ensure that you are consuming ample liquids during use to minimize this risk.

Condition treated

  • Colonoscopy, preparation for

Type of medicine

  • Laxative

Side Effects

In addition to the required laxative effects of the Sodium phosphate dibasic and sodium phosphate monobasic combination, unwanted side effects can occur. In some cases, these side effects can require the patient to seek medical attention, whilst in other cases, the side effects will abate over time and do not necessitate treatment. Before receiving the treatment you should review the side effects listed below so you know how to react if they occur.

You should check with your doctor immediately if any of the following side effects occur:

Occurring commonly:

  • Abdominal pain
  • Bloating
  • Feeling of fullness
  • Nausea
  • Stomach pain or cramps
  • Vomiting

Frequency of incidence not known:

  • Agitation
  • Bloody or cloudy urine
  • Burning or tingling feelings in the skin. Can occur all over the body.
  • Coma or loss of consciousness
  • Confusion or disorientation
  • Coughing
  • Decreased volume or frequency of urine output
  • Depression or feelings of extreme sadness
  • Difficult or labored breathing
  • Difficult or painful passing of urine
  • Difficulty in swallowing
  • Dizziness
  • Fainting or feeling of faintness
  • Headaches
  • Hives
  • Hostility
  • Irregular or changed heartbeat
  • Irritability or quickness to annoyance
  • Lethargy or undue tiredness
  • Muscle twitching or spasms
  • Noisy breathing or rattling of breath
  • Puffiness or swelling of the face, particularly on the eyelids tongue or lips
  • Rapid weight gain
  • Redness of the skin with or without lesions
  • Seizures or convulsions
  • Skin rash or itching
  • Stupor
  • Swelling of the face, ankles, or hands
  • Tightness in the chest
  • Unusual tiredness
  • Unusual weakness
  • Welts

It is possible to suffer from an overdose of this medication. If you believe that you or someone else is suffering from an overdose of this medication then you should contact the emergency services immediately. The symptoms of overdose are as follows. If you experience more than one of the following then you should seek treatment immediately.

Symptoms of overdose:

  • Abdominal pain
  • Blurry vision
  • Change in heart rate
  • Chest pain
  • Decrease in feelings of hunger
  • Decreased frequency of urine
  • Discomfort in the upper chest region
  • Dizziness or feeling of faintness or lightheadedness when rising from lying or sitting down suddenly.
  • Dry mouth or feeling of dehydration
  • Increase in weight
  • Increased thirstiness
  • Lightheadedness
  • Lower back
  • Muscle cramping experienced in the hands, arms, legs, feet or face
  • Muscle pain
  • Pounding or rapid pulse
  • Rapid breathing
  • Restlessness
  • Side pain
  • Stomach cramps
  • Sunken eyes or appearance of extreme tiredness
  • Sweating when warm
  • Tremor or shaking
  • Unusual weakness
  • Wrinkling of the skin

Other side effects from the use of this medication may occur that are not listed here. If you experience any other side effects then you should report them to your doctor for advice. If you are seriously concerned about a side effect that you are experiencing and believe yourself to be at risk then you should always contact the emergency services.


This medication should only be taken as directed by your doctor. Do not take more of it, take it more frequently than prescribed or take it for longer than ordered by your doctor.

This medication comes with a medication guide that you should read and understand before use. If you have any questions then seek clarification from your healthcare professional.

Each dose of 4 tablets should be taken with 8 ounces of water or clear liquid (approximately 1 large glass of water). A clear liquid is a liquid like water or flavored juice that is transparent. You should not consume thick or translucent liquids with this treatment. You should not drink any liquids that are colored purple or red.

When taking this medication you should drink as much fluid as you can before, during and after treatment. This treatment will cause you to lose a lot of fluids through your bowel movements and drinking more will help to protect your kidneys and will make the passing of stools more comfortable.

This medication should not be taken more than once within a 7 day period. Consult your doctor before using this medication more frequently than this.

The dose that you take of this medicine will vary for each patient. You should only take it as instructed and should not exceed the frequency of use ordered by your healthcare professional. The following is a guideline only and you should not change your dose unless instructed to by your doctor:

For cleaning of the colon:

  • Adults - Four tablets with 8 ounces of water every 15 minutes until twenty tablets have been taken. To be consumed in the evening before the colonoscopy.
  • Children - Use and dose to be determined by the doctor.


Some medications should not be taken together because they interact in the body and can have severe side effects for the patient. For this reason, it is essential that you inform your doctor of all medications that you are taking before you begin treatment with this medication. This includes all over the counter treatments, herbal remedies, vitamin supplements and other medications that you might be taking. It is particularly important that you inform your doctor if you are taking any of the following medications:

The use of sodium phosphate dibasic and sodium phosphate monobasic should not be used if you are taking any of the following medications. Your doctor may need to change one or more medication.

  • Ziprasidone
  • Thioridazine
  • Terfenadine
  • Sparfloxacin
  • Saquinavir
  • Piperaquine
  • Pimozide
  • Mesoridazine
  • Dronedarone
  • Cisapride
  • Bepridil
  • Amisulpride
  • Amifampridine

The use of the following in conjunction with sodium phosphate dibasic and sodium phosphate monobasic is not recommended. If both medications are prescribed then the dosage of one or other may need to be amended.

  • Zuclopenthixol
  • Voriconazole
  • Vinflunine
  • Vemurafenib
  • Vardenafil
  • Vandetanib
  • Triptorelin
  • Trimipramine
  • Trazodone
  • Tizanidine
  • Tetrabenazine
  • Telithromycin
  • Telavancin
  • Tacrolimus
  • Sunitinib
  • Sulpiride
  • Sotalol
  • Sorafenib
  • Solifenacin
  • Sevoflurane
  • Salmeterol
  • Ranolazine
  • Quinine
  • Quinidine
  • Quetiapine
  • Protriptyline
  • Propafenone
  • Promethazine
  • Prochlorperazine
  • Procainamide
  • Posaconazole
  • Pitolisant
  • Pimavanserin
  • Perflutren Lipid Microsphere
  • Pazopanib
  • Pasireotide
  • Panobinostat
  • Paliperidone
  • Ondansetron
  • Ofloxacin
  • Octreotide
  • Nortriptyline
  • Norfloxacin
  • Nilotinib
  • Nafarelin
  • Moxifloxacin
  • Mifepristone
  • Metronidazole
  • Methadone
  • Mefloquine
  • Lumefantrine
  • Lopinavir
  • Levofloxacin
  • Leuprolide
  • Lapatinib
  • Ketoconazole
  • Ivabradine
  • Imipramine
  • Iloperidone
  • Ibutilide
  • Hydroxyzine
  • Hydroxychloroquine
  • Histrelin
  • Haloperidol
  • Halofantrine
  • Granisetron
  • Goserelin
  • Gonadorelin
  • Gemifloxacin
  • Gatifloxacin
  • Fluoxetine
  • Fluconazole
  • Flecainide
  • Fingolimod
  • Escitalopram
  • Erythromycin
  • Efavirenz
  • Droperidol
  • Donepezil
  • Domperidone
  • Dolasetron
  • Dofetilide
  • Disopyramide
  • Deslorelin
  • Desipramine
  • Delamanid
  • Degarelix
  • Dasatinib
  • Dabrafenib
  • Crizotinib
  • Clozapine
  • Clomipramine
  • Clarithromycin
  • Citalopram
  • Ciprofloxacin
  • Chlorpromazine
  • Chloroquine
  • Buserelin
  • Bedaquiline
  • Azithromycin
  • Astemizole
  • Asenapine
  • Arsenic Trioxide
  • Aripiprazole
  • Apomorphine
  • Anagrelide
  • Amoxapine
  • Amitriptyline
  • Amiodarone
  • Alfuzosin

When using the following medications in conjunction with sodium phosphate dibasic and sodium phosphate monobasic, there may be increased risks of suffering certain side effects. If you are prescribed both then your doctor may with to amend the dose of one or more of the medications.

  • Magnesium Trisilicate
  • Magnesium Oxide
  • Magnesium Hydroxide
  • Magnesium Carbonate
  • Magaldrate
  • Dihydroxyaluminum Sodium Carbonate
  • Dihydroxyaluminum Aminoacetate
  • Calcium Citrate
  • Calcium Carbonate
  • Calcium Acetate
  • Aluminum Phosphate
  • Aluminum Hydroxide
  • Aluminum Carbonate, Basic

The medications listed herein have been chosen due to the severity of interactions and may not be all-inclusive. Ensure that you inform your doctor of all substances and medications that you are taking before using this treatment.

Medications can also interact with existing medical conditions. This treatment should not be used with certain medical conditions and it is vital that you disclose all health conditions from which you suffer or from which you have suffered in the past to your doctor. This is particularly important if you suffer from any of the following conditions:

Do not use in patients suffering from the following:

  • Acute phosphate nephropathy
  • Bowel problems
  • Previous stomach surgery
  • Stomach problems
  • Toxic colitis
  • Toxic megacolon

Risk of arrhythmia will be increased in patients suffering from the following:

  • Angina
  • Congestive heart failure
  • Heart disease
  • History of heart rhythm problems
  • Recent heart attack

These symptoms of the following conditions may be worsened if this treatment is used:

  • Arrhythmia
  • Dehydration
  • Electrolyte imbalance
  • History of inflammatory bowel disease
  • History of kidney disease
  • History of seizures
  • Hypovolemia
  • Trouble with swallowing or gastric reflex
  • Ulcerative colitis
  • Withdrawal symptoms from alcohol or benzodiazepines


Before taking this medication you should understand the risks of doing so and weigh them in relation to the benefits of taking the medication. You should make the decision to take this medication with your doctor and you should consider the following factors together.

Allergies - You should inform your doctor if you have ever had an allergic reaction to any medications before. Inform your doctor of any other allergies from which you suffer too.

Pregnancy - Risk of harm to a fetus cannot be ruled out when using this treatment during pregnancy. You should inform your doctor that you are pregnant before using this treatment. Alternative laxatives are available that do not pose as great a risk to the fetus during pregnancy. This treatment should only be used during pregnancy if it is clearly needed.

This medication should never be taken alongside other laxative medications or enema treatments that contain sodium phosphate. Doing so can result in the occurrence of serious unwanted side effects.

This medication can lead to serious kidney problems. You have a higher risk of developing this side effect if you are aged 55 or older, are dehydrated, have a low volume of blood or are taking other medications that affect the kidneys. To help avoid kidney problems you should ensure that you drink an appropriate amount of water. Doing so will help to keep you hydrated throughout the treatment and will reduce the impact on your kidneys by flushing the medication out. Signs of kidney problems should be reported to your doctor immediately that you notice them. The following are symptoms of kidney problems that should be reported:

  • Confusion or disorientation
  • Decreased volume or frequency of urination
  • Feeling dizzy
  • Dry mouth or feeling of dehydration
  • Faintness or fainting
  • Increase in heartrate
  • Rapid breathing or shallow breaths
  • Unusual tiredness
  • Unusual weakness

Do not take any other medications in conjunction with this medication without first discussing the use with your doctor.


This medication should be stored at room temperature in its original packaging away from heat, light and moisture. Prevent medication from freezing.

All medications should be kept out of the reach of children at all times.

Do not keep outdated medication for longer than needed.

Discuss how to dispose of unwanted and outdated medication with your doctor.


Sodium Phosphate Dibasic And Sodium Phosphate Monobasic is a powerful laxative used to clean the colon and bowels so that a colonoscopy can be performed on a patient.

The treatment is to be taken by the patient on the evening before the colonoscopy so that the colon is cleared in preparation for the treatment.

The treatment is usually taken in tablet form over a period of time with 15 minute intervals between doses. Each dose should be taken with 8 ounces of water. The usual dose is 4 tablets every 15 minutes until a total dose of 20 tablets has been consumed.

Water consumption before, during and after this treatment is very important. The patient will lose a lot of fluids through the passing of stools and it is important to replace this fluid. The medication will put the patient at risk of kidney problems and drinking a lot of fluids will help to minimize this risk.

Patients should be alert to any signs of kidney problems and should contact their doctor immediately if they suspect that any kidney problems are occurring.

Overdose can also occur from the use of this treatment and patients should be alert to the symptoms of overdose before taking this medication.

This medication should not be taken with any other medications or laxatives that contain sodium phosphate. Doing so will greatly increase the risks that the patient is exposed to.

This medication should not be used in pregnant women where it can be avoided. Alternative laxatives are available that can be used during pregnancy.

In preparation for the colonoscopy the patient will also need to follow some other steps. This can include managing your diet in the lead up to the colonoscopy to allow for the easier passing of stools. This can ease the process and make it more comfortable. The patient will also need to fast and avoid eating anything solid in the lead up to the treatment.

Last Reviewed:
December 23, 2017
Last Updated:
April 05, 2018
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