Constipation:

  • Is the most common digestive complaint in the United States [15]
  • 65 million Americans suffer from the discomfort of constipation [4]
  • Accounts for 2.5 million physician visits every year [18]

Quick reference

Medicines that may cause constipation*

Download this chart
Type of drug Primary use Active Ingredients Brand Examples
Antacids Relieve heartburn Brands containing aluminum, calcium Gaviscon®, Amphojel®
Anticonvulsants Control epilepsy and other seizure disorders Phenytoin, valproic acid Dilantin®, Depakote®
Antidepressants Treat symptoms of depression Amitriptyline, imipramine, nortriptyline Elavil®, Tofranil®, Pamelor®
Antihypertensives Lower blood pressure Diltiazem, nifedipine, clonidine hydrochloride Cardizem®, Procardia®, Catapres®
Anti-Parkinson's agents Relieve symptoms of Parkinson's disease Levodopa, carbidopa Sinemet®, Stalevo®
Antipsychotics Treat symptoms of psychosis Haloperidol, clozapine, risperidone Haldol®, Clozaril®, Risperdal®
Antispasmodics Decrease intestinal cramps, control overactive bladder Propantheline, dicyclomine, oxybutynin, tolterodine Pro-Banthine®, Benthyl®, Ditropan®, Detrol®
Bile acid sequestrants Reduce cholesterol Cholestyramine, colestipol Questran®, Colestipol®
Calcium supplements Supplement dietary calcium Calcium citrate, calcium carbonate Caltrate®, PhosCal®
Chemotherapy agents Treat cancer Vinca alkaloids, alkylating agents, others Oncovin®, Paraplatin®
Diuretics Lower blood pressure, promote excretion of water Furosemide, hydrochlorothiazide Lasix®, Aldactazide®, Aldoril®, HydroDIURIL®, Dyazide®
Iron supplements Iron deficiency anemia Ferrous fumarate, ferrous gluconate, ferrous sulfate Femiron®, Fergon®, Feosol®, Slow Fe®
Opioids Relieve pain Morphine, codeine, oxycodone MS Contin®, Tylenol® with Codeine, Percocet®, OxyContin®

*When used as directed.
The trademarks depicted in this table are owned by their respective owners.

Quick Reference

Comparison of constipation treatments

Download this chart
Brand name Type and active ingredient Indication How it works Considerations
MiraLAX® OTC Osmotic: Polyethylene glycol 3350 Occasional Constipation
  • Relieves occasional constipation by drawing water into the bowel from surrounding body tissues. This provides softer stools and increases the frequency of bowel movements
  • Provides both stool softening and laxative effects [1-9]
  • Generally produces a bowel movement in 1-3 days. Many get relief in 1 day
  • Unlikely to cause harsh side effects
  • Proven safe and effective in elderly patients [6]
  • No known drug-drug interactions [6]
  • One of only 2 laxatives with a Grade A recommendation from the American College of Gastroenterology [12]
  • Do not use if you have kidney disease except under the advice and supervision of a doctor

Dulcolax®

Correctol®

Ex-Lax®

Senokot®

Stimulant: Bisacodyl

Sennosides

 Occasional Constipation
  • Stimulates the walls of the intestine, causing the muscles to contract and clear the bowel
  • Generally produces a bowel movement in 6-12 hours
  • Can cause stomach discomfort, faintness, cramps, sudden urgent bowel movement
  • Do not use Bisacodyl within 1 hour after taking an antacid or milk
  • Sennosides may affect how other drugs work. Should be taken 2 hours before or after other drugs
Metamucil® Bulk-Forming (Fiber): Psyllium Husk Occasional Constipation
  • Softens and increases the bulk of digested food, making it easier for waste to travel through and leave the body
  • Generally produces effect in 12-72 hours
  • Ferments in the intestine, which may cause gas and bloating
  • May affect how well other medicines work. Take at least 2 hours before or 2 hours after prescribed medication
Colace OTC® Stool Softener: Docusate Sodium Occasional Constipation
  • Allows water and fats to get into the stool. This helps soften fecal material and makes defecation easier
  • Generally produces bowel movement in 12-72 hours
  • Does not force bowel movement
Phillips' Milk of Magnesia® Saline: Magnesium Hydroxide Occasional Constipation
  • Pulls large amounts of water into the intestine, making stool soft and loose. Increased fluid causes pressure that stimulates contractions in the intestines
  • Usually produces bowel movement in 30 minutes to 6 hours
  • Can produce urgent, loose stools
  • Can remove electrolytes [19]
  • May interact with certain prescription drugs
  • Patients with kidney disease or a magnesium restricted diet need to consult their doctor before use

Kristalose®

 Rx Osmotic: Lactulose Constipation
  • Draws fluid into the colon, lowering pH and increasing bowel movements [19,20]
  • Generally produces a bowel movement in 1-2 days
  • Potential significant side effects, including cramps, gas, diarrhea, nausea, and vomiting
  • People who have diabetes or require a low-lactose diet should consult a physician [20,21]

The trademarks depicted in this table are owned by their respective owners.

Diagnostic tools

There is no formal clinical definition of occasional constipation, and clinicians, patients, and diagnostic criteria define it differently.

However, chronic constipation is defined by the most recent Rome criteria:[22]

  • Presence of two or more of the following symptoms:
    • Straining during at least 25% of defecations
    • Lumpy or hard stools in at least 25% of defecations
    • Sensation of incomplete evacuation for at least 25% of defecations
    • Sensation of anorectal obstruction/blockage for at least 25% of defecations
    • Manual maneuvers to facilitate at least 25% of defecations (such as digital evacuation, support of the pelvic floor)
    • Fewer than three bowel movements a week
  • Loose stools are rarely present without the use of laxatives
  • Criteria have to have been met for the previous three months, with the onset of symptoms six months prior to diagnosis

Occasional constipation is often described as a departure from an individual's normal bowel movements and/or the presence of the same symptoms as chronic constipation (listed above). However, if symptoms last for 7 days or longer, a physician should be consulted.

The Bristol Scale

The Bristol Scale (referred to in the UK as the Meyers Scale) was developed at the University of Bristol. It can be used to monitor change in bowel consistency and helps the patient describe bowel movements in an objective and minimally embarrassing manner.

Types 1 and 2 on the Bristol Scale indicate constipation. Types 3 and 4 are the "ideal stools", especially the latter, as they are the easiest to defecate. Finally, types 5–7 tend towards diarrhea.

Type 1 Separate, hard lumps, like nuts (hard to pass)
Type 2 Sausage-shaped but lumpy
Type 3 Like a sausage but with cracks on its surface
Type 4 Like a sausage or snake, smooth and soft
Type 5 Soft blobs with clear-cut edges (passed easily)
Type 6 Fluffy pieces with ragged edges, a mushy stool
Type 7 Watery, no solid pieces. Entirely liquid
Download Bristol Scale PDF

The Bristol Stool Scale was created by Lewis SJ, Heaton KW. Scand J Gastroenterol. 1997.

Women are more at risk of developing constipation than are men

In North America, women are 2.2 times more likely than men to report constipation [22,23]

A number of factors may lead to constipation in women:

Hormones

The reported incidence of constipation premenstrually ranges from 16% to 32% [24]

  • The relationship between menstruation and constipation may be due to the raised concentration of progesterone in the luteal phase, which may reduce gastrointestinal motility [24,25]
    • The release of uterine prostaglandins (PGs) at the start of menses may stimulate the muscles of the gut to contract, thus increasing motility [24]
Diet

Cyclical food intake during menstruation may affect cyclical bowel habits

  • Women's food intake may increase as much as 35% during the luteal phase [24]
  • Women have reported an increase in appetite and/or a craving for sweet food premenstrually [24]
Pregnancy

Constipation measured using the Rome criteria affects up to one-fourth of women throughout pregnancy [26]

  • Post-partum women may experience constipation that persists for as long as 9 months [27]

MiraLAX® laxative was category C when it was sold by prescription. Patients who are nursing or pregnant should consult their physician before taking MiraLAX.

Supplemental iron

Iron deficiency is especially common among women of childbearing age due to pregnancy and menstrual blood loss [28]

  • Constipation may be a side effect of iron supplementation [28]
Supplemental calcium

Many women take calcium supplements, which can have a binding effect [29,30]

Menopause

High prevalence of constipation in postmenopausal women has been reported [31]

  • History of perianal surgery and presence of hemorrhoids have been associated with constipation [31]