Dulcolax

What bisacodyl is and how it works

Dulcolax (bisacodyl) is a stimulant laxative used for the short-term relief of occasional constipation, and to empty the bowel before certain diagnostic procedures or surgery. It works by stimulating the muscles of the bowel wall, usually producing a bowel movement within 6 to 12 hours (tablets) or 10 to 30 minutes (suppositories). (1) (5)

This is a widely available, over-the-counter medicine with no boxed warning in any market reviewed. Its main real safety points are: avoid it if you have a bowel blockage or a severe, undiagnosed abdominal condition; do not use it continuously for more than a few days without seeing a clinician about the underlying cause of constipation; and some people feel dizzy or briefly faint around a bowel movement while using it, which is usually a mild reflex response to straining rather than a direct effect of the medicine itself.

Mechanism of action: how bisacodyl works

Bisacodyl is a diphenylmethane derivative stimulant laxative. After hydrolysis in the gut, its active metabolite stimulates sensory nerve endings in the colonic mucosa, increasing peristalsis (bowel muscle contraction) and altering fluid/electrolyte movement to soften stool and promote a bowel movement. (5)

What is Bisacodyl used for?

Before taking bisacodyl

Do not take / not appropriate for

• Do not take Dulcolax if you have a bowel blockage (ileus or intestinal obstruction). (all countries) (2) (5)
• Do not take Dulcolax if you have an acute abdominal condition such as appendicitis, or an acute flare of inflammatory bowel disease. (all countries) (2) (5)
• Do not take Dulcolax if you have severe abdominal pain together with nausea and vomiting -- this can be a sign of a more serious condition needing urgent assessment. (all countries) (2) (5)
• Do not take Dulcolax if you are severely dehydrated, or have a known allergy to bisacodyl or any ingredient in the product. (all countries) (2) (5)
• Do not chew or crush the tablets, and do not take them within an hour of antacids, milk, or certain acid-reducing medicines -- this can cause the coating to dissolve too early and lead to stomach upset. (all countries) (1) (2)

Tell your clinician about

• Whether you have kidney problems, are elderly, or are otherwise at higher risk of dehydration.
• Whether you have ongoing or recurring constipation that hasn't been assessed by a clinician.
• Any rare hereditary conditions affecting lactose, sucrose, or fructose tolerance (relevant to some tablet formulations).
• Whether you have anal fissures or ulcerative proctitis, if using the suppository form.

Bisacodyl dosage and how to take it

• Swallow tablets whole with enough fluid -- do not chew or crush them.
• Take tablets at night; they are designed to produce a bowel movement the following morning.
• For suppositories: insert pointed-end first into the rectum; warming it briefly in your hand before removing the foil wrapper can help it go in more easily -- do not coat it in paraffin oil or petroleum jelly.
• Do not use for more than a few days in a row without talking to a clinician about the underlying cause of your constipation.

Procedures and treatment changes

Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2) (3) (4) (5)

Missed dose

Dulcolax is used as needed for occasional constipation rather than on a fixed daily schedule, so a 'missed dose' does not usually apply. If you are using it regularly for an ongoing condition, contact your pharmacist or clinician for guidance rather than adjusting the schedule yourself.

Overdose

Seek medical attention or contact a poison control service if too much has been taken, especially in children, or if severe abdominal pain, persistent diarrhoea, or signs of dehydration (such as reduced urination or extreme thirst) develop. (5)

Bisacodyl side effects

Side effects and their urgency vary; report severe, persistent, or concerning symptoms.

Serious warnings

Interactions

• Antacids, milk, and certain acid-reducing medicines (such as some proton pump inhibitors) taken within an hour of the tablet can cause its protective coating to dissolve too early, leading to stomach irritation and reduced effectiveness. (1) (2)
• Other laxatives or diuretics used together with Dulcolax may increase the risk of dehydration and electrolyte imbalance. (2)

Pregnancy, breastfeeding, kidney/liver function, age

Monitoring

Before starting

• Confirm there is no bowel obstruction, acute abdominal condition, or severe dehydration
• Consider whether ongoing constipation needs clinical assessment rather than repeated self-treatment

During treatment

• Watch for signs of dehydration or electrolyte imbalance with continued use beyond a few days.
• Reassess with a clinician if constipation persists beyond short-term, occasional use.

Storage

Store at room temperature, away from moisture, and out of reach of children -- accidental ingestion by children should prompt medical advice.

Frequently asked questions

References

1. DULCOLAX (bisacodyl) tablet, coated -- OTC drug facts labelU.S. Food and Drug Administration / DailyMed (NIH), OTC drug facts label · United States · accessed 2026-07-30 · source 1
2. Dulcolax Adult 5 mg Gastro-resistant Tablets and Dulcolax 5 mg/10 mg Suppositories -- Summary of Product Characteristicselectronic medicines compendium (emc), United Kingdom -- Opella Healthcare UK Limited / Opella POM UK Limited · United Kingdom · accessed 2026-07-30 · source 2
3. Health Canada Drug Product Database -- live query results for 'Dulcolax'Health Canada Drug Product Database (official API) · Canada · accessed 2026-07-30 · source 3
4. TGA PICMI search for 'bisacodyl' -- 4 documentsTherapeutic Goods Administration (TGA), Australia -- PICMI repository · Australia · accessed 2026-07-30 · source 4
5. DULCOLAX (bisacodyl) New Zealand Data Sheet (dultabsup-ccdsv2-dsv5, dated 2024-04-12)Medsafe (New Zealand regulator) -- official New Zealand Data Sheet · New Zealand · accessed 2026-07-30 · source 5
6. No centralised EU authorisation applies to bisacodyl OTC products; national-database confirmation attempt inconclusiveEuropean national medicines databases (attempted: France ANSM base-donnees-publique.medicaments.gouv.fr) · European Union · accessed 2026-07-30 · source 6

Brand names by country

Single-ingredient bisacodyl names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.

Priority countries