Skip to content
ClinCalc Pro
Menu
Calculators Drugs Pathways AI Dx Donate Get the App
Stimulant Laxative

Bisacodyl

Brand names: Dulcolax

Bisacodyl is a stimulant laxative used for constipation and for bowel preparation before procedures.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: Constipation, adults and children over 12 years: 1 to 2 coated tablets (5 – 10 mg) daily before bedtime. Start with the lowest dose and adjust upwards only as needed. Each coated tablet contains 5 mg — the strength is pinned by the product, 'Bisacodyl 5mg Laxative Tablets 12+ years'. ORAL TABLETS ONLY: the rectal suppository route shown elsewhere on this page is not covered by this source.
Route: Oral — enteric-coated tablets. §4.2 verbatim: 'It is recommended to take the coated tablets at night to have a bowel movement the following morning. They should be swallowed whole with an adequate amount of fluid. The coated tablets should not be taken together with products which reduce the acidity of the upper gastrointestinal tract, such as milk, antacids or proton pump inhibitors, in order not to prematurely dissolve the enteric coating.'
Frequency: Once daily, before bedtime.
Max: Maximum 10 mg (2 coated tablets) daily — the top of the only range stated for this indication. §4.2 verbatim: 'Adults and children over 12 years: 1 to 2 coated tablets (5 - 10 mg) daily before bedtime… It is recommended to start with the lowest dose. The dose may be adjusted up to the maximum recommended dose to produce regular stools. The maximum daily dose should not be exceeded.' No figure above 10 mg daily appears anywhere in the fetched SPC.
SCOPE — ORAL TABLETS, CONSTIPATION. This is the whole of the posology in the fetched UK SPC; the bundle contains no strength-pinned suppository dose and no bowel-preparation regimen. || VERBATIM §4.2: 'Adults and children over 12 years: 1 to 2 coated tablets (5 - 10 mg) daily before bedtime. Should not be used in children and adolescents under the age of 12 years. It is recommended to start with the lowest dose. The dose may be adjusted up to the maximum recommended dose to produce regular stools. The maximum daily dose should not be exceeded. In the management of constipation, once regularity has been restarted dosage should be reduced and can usually be stopped.' || COURSE LENGTH — §4.4 verbatim: 'As with all laxatives, bisacodyl should not be taken on a continuous daily basis for more than five days without investigating the cause of constipation. Long-term everyday use of stimulant laxatives may harm the intestinal function and should be avoided… This product should only be used if a therapeutic effect cannot be achieved by a change of diet or the administration of bulk forming agents.' || ELDERLY — §4.2 verbatim: 'No specific information on the use of this product in the elderly is available. Clinical trials have included patients over 65 years and no adverse reactions specific to this age group have been reported.' || WEIGHT LOSS — §4.4: 'Stimulant laxatives (including bisacodyl) do not help with weight loss… They do not reduce the absorption of calories or nutrients.' || SUPPOSITORY, FOR THE RECORD ONLY — the US cross-check label ('Walgreens Gentle Laxative') states verbatim: 'adults and children 12 years of age and older 1 suppository once daily'. Its fetched text nowhere gives the suppository strength, so this count is not publishable as a dose and the page's '10mg per suppository' figure is not sourced from this bundle. || UNSOURCED FIGURES CURRENTLY ON THE PAGE: the onset times ('acts in 10–12 hours' oral, 'acts in 20–60 minutes' rectal), the suppository strength '10mg', the bowel-preparation regimen '10mg oral the evening before colonoscopy followed by macrogol', and the 'no evidence of long-term harm' claim — none appears in this bundle. The SPC's own §4.4 in fact warns the opposite about long-term use: 'Long-term everyday use of stimulant laxatives may harm the intestinal function and should be avoided.'

Paediatric dose

Route: Oral (coated tablets)
Frequency: Once daily before bedtime — children over 12 years take the adult dose.
NOT WEIGHT-BASED AND NOT LICENSED UNDER 12 YEARS in the primary source, so dosePerKg is null and the weight calculator is deliberately left unset. §4.2 verbatim: 'Adults and children over 12 years: 1 to 2 coated tablets (5 - 10 mg) daily before bedtime. Should not be used in children and adolescents under the age of 12 years.' §4.4 repeats: 'Should not be used in children and adolescents under the age of 12 years.' Children over 12 therefore take the adult dose above. || The US cross-check label in this bundle does carry a paediatric direction for a SUPPOSITORY — verbatim: 'adults and children 12 years of age and older 1 suppository once daily children 6 to under 12 years 1/2 suppository once daily children under 6 years do not use' — but its fetched text nowhere states the suppository strength, so that count cannot be converted into a milligram dose and is NOT published here. US OTC labelling may also differ from UK labelling. || Verify any paediatric dose against a children's formulary. || The page currently states a paediatric maxDose of '10mg' with no age band; the SPC gives no paediatric dose at all below 12 years.

Dose adjustments

Renal

Not stated — no renal-impairment dose adjustment appears in any fetched section (§4.2, §4.3, §4.4, §4.6, §4.8). §4.4 does carry a renal caution that is about stopping the drug, not adjusting it: 'In patients suffering from fluid loss where dehydration may be harmful (e.g. renal insufficiency, elderly patients) bisacodyl should be discontinued and only be restarted under medical supervision.' The page's current 'No dose adjustment required' is an inference, not a quotation from this SPC.

Hepatic

Not stated — no hepatic-impairment dosing or adjustment statement appears in any fetched section of this SPC (§4.2, §4.3, §4.4, §4.6, §4.8). The page's current 'No dose adjustment required' is an inference, not a quotation from this SPC.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

US labelling (FDA)

Reference — US labelling, may differ from UK

Directions -detach one suppository from the strip -remove wrapper before inserting into the rectum adults and children 12 years of age and older 1 suppository once daily children 6 to under 12 years 1/2 suppository once daily children under 6 years do not use

Source: US FDA prescribing information (openFDA / DailyMed), label dated 2026-01-15. Accessed 2026-06-12. US dosing and indications can differ from UK practice — use UK sources for prescribing decisions.

Contraindications

  • Ileus — §4.3 verbatim: 'Bisacodyl Laxative Tablets are contraindicated in patients with ileus, intestinal obstruction, acute abdominal conditions including appendicitis, acute inflammatory bowel diseases, and severe abdominal pain associated with nausea and vomiting which may be indicative of the aforementioned severe conditions.'
  • Intestinal obstruction (§4.3)
  • Acute abdominal conditions including appendicitis (§4.3)
  • Acute inflammatory bowel diseases (§4.3)
  • Severe abdominal pain associated with nausea and vomiting, which may indicate any of the above (§4.3)
  • Severe dehydration — §4.3: 'Bisacodyl Laxative Tablets are also contraindicated in severe dehydration…'
  • Known hypersensitivity to bisacodyl or any other component of the product (§4.3)
  • Hereditary conditions incompatible with an excipient — §4.3: 'In case of hereditary conditions that may be incompatible with an excipient of the product… the use of the product is contraindicated.' §4.4 names them: 'Bisacodyl Laxative Tablets contain a small amount of lactose and sucrose in each tablet. Patients with rare hereditary problems of fructose intolerance, galactose intolerance, total lactase deficiency, glucose-galactose malabsorption or sucrase-isomaltase insufficiency should not take this medicine.'
  • Not a contraindication but a licence restriction (§4.2 and §4.4): 'Should not be used in children and adolescents under the age of 12 years.'

Side effects

  • Common: abdominal cramps, abdominal pain, diarrhoea and nausea — §4.8: 'The most commonly reported adverse reactions during treatment are abdominal pain and diarrhoea.'
  • Uncommon: dizziness
  • Uncommon: haematochezia (blood in stool), vomiting, abdominal discomfort, anorectal discomfort
  • Rare: syncope — §4.8: 'Dizziness and syncope occurring after taking bisacodyl appear to be consistent with a vasovagal response (e.g. to abdominal spasm, defaecation).'
  • Rare: anaphylactic reactions, angioedema, hypersensitivity
  • Rare: dehydration
  • Rare: colitis including ischaemic colitis — §4.4 adds: 'There have been isolated reports of abdominal pain and bloody diarrhoea occurring after taking bisacodyl. Some cases have been shown to be associated with colonic mucosal ischaemia.'
  • §4.4: 'Prolonged excessive use may lead to fluid and electrolyte imbalance and hypokalaemia. Intestinal loss of fluids can promote dehydration. Symptoms may include thirst and oliguria.'

Monitoring

  • Course length — §4.4 verbatim: 'As with all laxatives, bisacodyl should not be taken on a continuous daily basis for more than five days without investigating the cause of constipation.'
  • Cause of constipation — §4.4: 'Long-term everyday use of stimulant laxatives may harm the intestinal function and should be avoided. If laxatives are needed every day the cause of the constipation should be investigated.'
  • Fluid and electrolyte status with prolonged excessive use — §4.4: 'Prolonged excessive use may lead to fluid and electrolyte imbalance and hypokalaemia.'
  • Patients in whom dehydration may be harmful — §4.4: 'In patients suffering from fluid loss where dehydration may be harmful (e.g. renal insufficiency, elderly patients) bisacodyl should be discontinued and only be restarted under medical supervision.'
  • Rectal bleeding — §4.4: 'Patients may experience haematochezia (blood in stool) that is generally mild and self-limiting. If the symptoms worsen during the use of the medicinal product, a doctor or pharmacist should be consulted.'
  • Abdominal pain with bloody diarrhoea — §4.4 links isolated reports to colonic mucosal ischaemia; consider ischaemic colitis.
  • Response and step-down — §4.2: 'In the management of constipation, once regularity has been restarted dosage should be reduced and can usually be stopped.'

Clinical monograph

How it works

It stimulates the enteric nerves of the colon to increase peristalsis and also promotes fluid and electrolyte accumulation in the bowel lumen, softening stool and hastening transit.

Prescribing in practice

  • Avoid in intestinal obstruction, ileus, acute abdominal conditions and acute inflammatory bowel disease.
  • Abdominal cramps and discomfort are common, and prolonged excessive use can lead to fluid and electrolyte disturbance.
  • Oral tablets are enteric coated and should not be taken with milk or antacids, which can cause premature dissolution and gastric irritation.

Monitoring

No routine monitoring is needed for short-term use; with prolonged or high-dose use consider fluid balance and electrolytes, particularly potassium.

Counselling the patient

  • Tablets usually work overnight, so they are typically taken at bedtime, whereas suppositories act within about an hour.
  • Swallow tablets whole without milk or antacids close to the dose, and maintain a good fluid intake.
  • Seek advice if you have severe abdominal pain, vomiting or no bowel movement despite treatment.

Evidence & guidelines

Standard stimulant laxative option (NICE CKS constipation).

Reference: BSG Bowel Preparation Guidelines; SPC Dulcolax; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). 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
Drugs
Pathways