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Clinician’s Corner: Laxatives that Result in Soft or Loose stool in 6-12 hours

Bisacodyl (oral) Dulcolax® 5mg 5-15mg daily at bedtime
Senna Senokot® 8.6mg 2 at bedtime,    max=4 daily
Magnesium hydroxide Milk of Magnesia (400/5) 30-60ml at bedtime

Stimulant agents

USE: Are effective as initial therapy to treat constipation but should not be used for more than 1 week, without a physician recommendation.

HOW IT WORKS: Increases contractions by local irritation of the intestinal smooth muscle, stimulating secretion of water and electrolytes.


  • Causes discoloration of urine
  • Temporary measure, do not use for longer than one week, without consultation.
  • These agents are often abused.
  • Are excreted in breast milk.
  • May cause harmless darkening pigmentation of colon
  • May color the urine from pink to brown.
  • Senokot® (senna) 8.6mg/ tablet.

Dosage:  start 2 tablets at bedtime do not exceed 2 tablets twice daily

Senna is often combined with a docusate.

  • Dulcolax® (bisacodyl) 5mg tablets 10mg suppositories

Dosage: start with 1 tablet at bedtime. Usual adult dose is 2 tablets at bedtime.

NOTE: this product has a protective coating so do not crush or chew. Do not take within 1 hour of antacids, milk or any product that raises gastric pH.

Magnesium hydroxide

USE: can be used as an antacid for temporary relief of heartburn, or occasionally as a laxative.

HOW IT WORKS: Highly osmotic ions draw water into the intestine and cause an increase in the pressure inside the bowels, thereby exerting movements of the feves.

Drug interactions : be sure to consult your Thompson Pharmacist and have them check for drug interactions with heart medications and antibiotics.

Patient information:

  • May lead excessive magnesium levels, especially in patients with kidney disease.
  • May see abdominal cramping, excessive urination, nausea, vomiting, dehydration electrolyte disturbances, loss of bowel control.
  • Milk of Magnesia 400mg/5ml

Is an 8% suspension of magnesium hydroxide

Antacid: For the temporary relief of heartburn, upset stomach, sour stomach, or acid indigestion.

Laxative: For relief of occasional constipation. Expect results within 30 minutes to 6 hours.

Dose: 1 to 2 ounces at bedtime. Shake well before using and follow dose with 8 oz of water.

Some drug companies use their “brand names” for different laxative products.  Be sure to consult your Thompson Pharmacist for any laxative selection.