Skip to content
ClinCalc Pro
Menu
Calculators Drugs Pathways AI Dx Donate Get the App
Phosphate enema / oral bowel preparation Pregnancy: Section 4.6: 'As there is no relevant data available to evaluate the potential for foetal malformation or other foetotoxic effects when administered during pregnancy Cleen Ready-to-Use Enema should only be used as directed by a physician at the time of delivery or postpartum. As sodium phosphate may pass into the breast milk, it is advised that breast milk is expressed and discarded for at least 24 hours after receiving the Cleen Ready-to-Use Enema.'

Sodium acid phosphate with sodium phosphate

Brand names: Fleet Phospho-soda, Fleet Ready-to-use enema

This is an oral phosphate bowel-cleansing preparation combining sodium acid phosphate with sodium phosphate, used to empty the bowel before procedures such as colonoscopy or surgery.

Adult dose

Dose: Occasional constipation, or bowel cleansing (e.g. before and after lower bowel surgery, delivery and post partum, before proctoscopy, sigmoidoscopy or colonoscopy, before radiological examination of the lower bowel): adults, elderly and children over 12 years - 1 bottle (118 ml delivered dose; 21.4 g sodium dihydrogen phosphate dihydrate + 9.4 g disodium phosphate dodecahydrate), no more than once daily or as directed by a physician.
Route: Rectal (enema)
Frequency: No more than once daily, or as directed by a physician
Max: 1 bottle (118 ml delivered dose) no more than once daily (SPC section 4.2); administration of more than one enema in a 24 hour period can be harmful (section 4.4)
Strength (SPC section 2): each 118 ml dose delivers the equivalent of 21.4 g (18.1% w/v) sodium dihydrogen phosphate dihydrate and 9.4 g (8.0% w/v) disodium phosphate dodecahydrate; contains 4.4 g sodium per 118 ml delivered dose. ROUTES NOT COVERED: this SPC is for a RECTAL enema only ('For rectal use only'); the page's oral route and any oral sodium phosphate preparation are not covered by this source and no oral dose is written. The SPC also states that no other sodium phosphate preparations, including sodium phosphates oral solution or tablets, should be given concomitantly (sections 4.3, 4.5). Method (section 4.2): lie on left side with both knees bent; with steady pressure gently insert the Comfortip into the anus with the nozzle pointing towards the navel; squeeze the bottle until nearly all liquid is expelled; discontinue if resistance is encountered - forcing the enema can result in injury. Generally 2 to 5 minutes are sufficient to obtain the desired effect; if delayed, discontinue further use and consult a physician. For occasional constipation rectal enemas are for short-term relief only. Section 4.4: evacuation normally occurs about 5 minutes after administration (retention over 5 minutes is not recommended); if evacuation does not occur or retention lasts more than 10 minutes serious side effects could occur - give no further administrations and have a physician assess the patient. Repeated and prolonged use is not recommended (habituation); unless directed by a physician it should not be used for more than one week. Do not use when nausea, vomiting or abdominal pain is present unless directed by a physician. Contains benzalkonium chloride (80 mg per 118 ml delivered dose). Source product: Cleen Ready-to-Use Enema (SPC brand); the page's Fleet brand names are not themselves covered by this bundle.

Paediatric dose

Dose: Children over 12 years: 1 bottle (118 ml delivered dose), no more than once daily or as directed by a physician (same as adult). Children aged 3 years to less than 12 years: as directed by a physician (the SPC gives no figure).
Route: Rectal (enema)
Frequency: No more than once daily, or as directed by a physician
As printed in SPC section 4.2 ('Adults, Elderly and Children over 12 years old'). No dose is written for children 3 to under 12 years because the SPC defers to a physician. Contraindicated in children under 3 years of age (sections 4.2, 4.3). Electrolyte shifts are of particular concern in children with megacolon or any other condition where there is retention of enema solution (section 4.4). Use a children's formulary for any child under 12.

Dose adjustments

Renal

SPC 4.2: do not administer to patients with clinically significant impairment of renal function (contraindicated, section 4.3). The product should be used with caution in patients with impaired renal function, when the clinical benefit is expected to outweigh the risk of hyperphosphataemia (sections 4.2, 4.4).

Hepatic

SPC 4.2: no dose adjustment is required in patients with hepatic impairment.

Dose independently re-sourced from UK Summary of Product Characteristics (SPC) via MHRA Products — clinician-reviewed. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

  • Hypersensitivity to the active ingredients or to any of the excipients (section 4.3)
  • Conditions causing increased absorption capacity or decreased elimination capacity, such as bowel obstruction or decreased bowel motility: suspected intestinal obstruction, paralytic ileus, anorectal stenosis, imperforate anus, congenital or acquired megacolon, Hirschsprung's disease (section 4.3)
  • Undiagnosed gastrointestinal pathology, e.g. symptoms suggestive of appendicitis, intestinal perforation or active inflammatory bowel disease; undiagnosed rectal bleeding (section 4.3)
  • Congestive heart failure (section 4.3)
  • Dehydration (section 4.3)
  • Children under 3 years of age (section 4.3)
  • Clinically significant impairment of renal function (section 4.3)
  • Concomitant use of any other sodium phosphate preparation, including sodium phosphates oral solution or tablets (sections 4.3, 4.5)

Side effects

  • Very rare (section 4.8): hypersensitivity e.g. urticaria; blister, pruritus, stinging
  • Very rare (section 4.8): dehydration, hyperphosphataemia, hypocalcaemia, hypokalaemia, hypernatraemia, metabolic acidosis
  • Very rare (section 4.8): nausea, vomiting, abdominal pain, abdominal distension, diarrhoea, gastrointestinal pain, anal discomfort and proctalgia
  • Very rare (section 4.8): rectal irritation, pain, stinging, chills
  • Patients should expect liquid stools and be encouraged to drink clear liquids to help prevent dehydration (section 4.4)
  • Hypernatraemia, hyperphosphataemia, hypocalcaemia and hypokalaemia may occur with clinical signs such as tetany and renal failure (section 4.4)
  • Forcing the enema can result in injury; rectal bleeding after use may indicate a serious condition - stop and assess (section 4.4)

Interactions

  • Calcium channel blockers, diuretics, lithium and other medications that might affect electrolyte levels - use with caution; hyperphosphataemia, hypocalcaemia, hypokalaemia, hypernatraemic dehydration and acidosis may occur (section 4.5)
  • Lithium - hypernatraemia is associated with lower lithium levels, so concomitant use could lead to a fall in serum lithium levels with a lessening of effectiveness (section 4.5)
  • Other sodium phosphate preparations including oral solution or tablets - should not be given concomitantly (sections 4.3, 4.5)
  • Diuretics, ACE inhibitors, angiotensin receptor blockers and NSAIDs (medications which may decrease glomerular filtration rate) - dehydration risk; encourage clear liquids (section 4.4)
  • QT-prolonging medicines (e.g. amiodarone, arsenic trioxide, azithromycin, erythromycin, clarithromycin, citalopram, domperidone) - use with caution (section 4.4)

Monitoring

  • Electrolyte levels before and after administration where electrolyte disorders are suspected and in patients who may experience hyperphosphataemia (section 4.4)
  • Signs of dehydration and electrolyte disturbance (tetany, renal failure) (section 4.4)
  • Evacuation expected at about 5 minutes; if no evacuation or retention exceeds 10 minutes give no further administrations and have a physician assess, who will decide on laboratory tests for electrolyte abnormalities (section 4.4)
  • Rectal bleeding after use - discontinue immediately and assess (section 4.4)

Clinical monograph

How it works

The osmotically active phosphate salts draw water into the bowel lumen, increasing intraluminal volume to stimulate peristalsis and produce evacuation.

Prescribing in practice

  • It can cause clinically significant fluid and electrolyte disturbances including hyperphosphataemia, hypocalcaemia and dehydration, with a risk of acute phosphate nephropathy, so it is contraindicated or used with great caution in renal impairment, heart failure and the elderly.
  • Adequate oral hydration must be maintained throughout, and concomitant drugs affecting fluid or electrolyte balance such as diuretics, ACE inhibitors and lithium increase the risk.
  • It is contraindicated in suspected bowel obstruction, ileus or active inflammatory bowel disease.

Monitoring

Assess renal function, hydration and electrolytes before use in at-risk patients and ensure generous fluid intake during bowel preparation.

Counselling the patient

  • Drink the recommended clear fluids generously to avoid dehydration.
  • Report dizziness, palpitations, severe vomiting or markedly reduced urine output.
  • Tell the team about kidney or heart problems and any water tablets you take.

Evidence & guidelines

MHRA advice highlights the risk of severe electrolyte disturbance and renal injury with oral phosphate bowel-cleansing preparations, supporting careful patient selection.

Reference: NICE; MHRA; Confirm identity and dosing against the manufacturer SPC (eMC) and NICE. Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

Calculators
Pathways