US Pharm. 2013;38(12):8-11.
Patients often consult pharmacists for assistance with
gastric and digestive complaints, such as diarrhea, gastroesophageal
reflux, and bloating. One of the most common complaints is constipation.
It is critical for the pharmacist to be fully aware of different
options for preventing and treating constipation.
Prevalence and Epidemiology of Constipation
Experts estimate that 15% of the population is affected with constipation, which is approximately 42 million people.1 Within this group, 4 million people suffer from frequent constipation, and 12% to 19% are chronically constipated.2,3 The laxative market in the United States alone is approximately $725 million yearly.2
Constipation affects people of all races and ages, and both sexes.1 However, it is more common in women, in those over the age of 65 years, in non-Causcasians, and in lower socioeconomic classes.1,2 As many as 17% to 45% of women experience constipation during pregnancy.4
Evaluating the Patient’s Medical Record
When a patient complains of constipation, the pharmacist must be alert to the possibility that medications may be the cause.5,6
A host of drugs can be responsible, including narcotic analgesics
(e.g., opiate derivatives), antacids with aluminum hydroxide or calcium
carbonate, calcium channel blockers, diuretics, Parkinson’s medications,
antispasmodics, antidepressants, iron or calcium supplements, and
anticonvulsants.1 If a medication is suspected as
the cause, the patient should be urged to discuss the problem with the
prescriber so alterations to the regimen might be considered.
When to Refer Patients to a Physician
Patients should be referred to a physician in the
following situations (among others): 1) the patient has a serious
underlying medical condition (e.g., Parkinson’s disease, diabetes); 2)
the patient is a possible laxative abuser/misuser (discussed below); 3)
constipation has lasted longer than 7 days; 4) the patient also
complains of abdominal pain, nausea, and/or vomiting (possible signs of
appendicitis); 5) the patient has rectal bleeding or a sudden change in
bowel habits that lasts for 2 weeks or longer; 6) the patient has an
ileostomy or colostomy; 7) the patient is pregnant or breastfeeding; 8)
constipation alternates with diarrhea; 9) the patient has rectal pain or
sharp/severe abdominal pain, especially if the latter is accompanied by
bloating; 10) stools are thin or pencil-like; 11) the patient has
unexplained weight loss; or 12) the patient has used a laxative and/or
instituted lifestyle changes, but remains constipated.7-10
Pharmacists must also be alert to potential misuse and abuse of laxatives, as mentioned in the referral list above.7,11
There are several types of abuse. For example, wrestlers may be
instructed by their coaches to use laxatives to weigh in at a lower
number in hopes that they can win a bout. In other cases, persons with
anorexia or bulimia intentionally attempt to lose weight by continued
use of laxatives, often those containing harsh stimulants such as
bisacodyl or senna. Repeated purchases by thin or drastically
underweight women should trigger an alarm. Another group of abusers
administer laxatives to family members or children for whom they provide
care, enjoying the resulting medical attention given to the victim. A
final group is patients who use laxatives over the 7-day limit, becoming
If pharmacists suspect any of these issues, a refusal to
sell is warranted. This can be accomplished by placing laxatives of
abuse behind the counter, with a sign informing patients that they must
ask the pharmacist for them. This allows the pharmacist to ask questions
prior to sale.
Check the Patient’s Age
Laxatives and fiber products carry age limits below which they are not safe for self-treatment.7
Some of the products that are safe down to the age of 2 years include
glycerin suppositories and enemas, polycarbophil, docusate, magnesium
hydroxide (e.g., Phillips’ Milk of Magnesia), sodium phosphate enemas,
mineral oil enemas, magnesium citrate, castor oil, and senna. Products
safe only down to the age of 6 years include methyl-cellulose, psyllium,
oral mineral oil, and bisacodyl. Carbon dioxide suppositories should
not be used by anyone under the age of 12 years, and polyethylene glycol
(PEG) 3350 is not safe for those under 17 years.7
Types of Laxatives
PEG 3350: This
type (e.g., MiraLAX) is indicated for relief of occasional constipation
and generally produces a bowel movement in 1 to 3 days. The
manufacturer explains its action as “gently replenishing the water” in
the digestive system.12 Patients should not use PEG 3350
without a physician’s advice if they have kidney disease, nausea,
vomiting, abdominal pain, a sudden change in bowel habits that lasts
more than 2 weeks, or irritable bowel syndrome. Patients should not use
it without speaking to a physician or pharmacist if they are taking any
prescription drugs. They should stop use and seek physician advice in
the following situations: they have rectal bleeding; their nausea,
bloating, cramping, or abdominal pain worsens; they develop diarrhea; or
they need to use a laxative for longer than 1 week. Patients are
directed to fill the cap to the indicated level, which will deliver 17
g, mix the product with a 4- to 8-oz beverage of any temperature, and
drink once daily.12
Fiber Replacement Products: These products replace fiber in the diet, acting as dietary supplements.7
They do not force expulsion of fecal contents as stimulants do, but
attract water to promote healthy bowel movements. Patients may not
notice a difference until 2 to 3 days have passed. These products may be
taken up to 3 times daily for 7 days to treat constipation. However, if
used to prevent constipation by bulking up the diet, they may be taken
indefinitely, unless the patient has a contraindication to their use.
Fiber replacement products are inappropriate in several circumstances,
including fluid limitations (e.g., renal disease), large intestinal
ulcerations or adhesions, partial bowel obstruction, fecal impaction,
dysphagia, and gastrointestinal strictures, or in patients who are
bedridden and have colonic distension. They are also inappropriate when
a prompt, thorough bowel evacuation is needed, as for an upcoming x-ray
Patients must be advised to dilute powdered bulks as
advised, and to take them quickly to prevent overthickening that would
hamper ingestion.7 If the patient does not dilute the product
as needed, it could conceivably block the throat or esophagus to cause
choking. Patients should immediately call 911 if they develop chest
pain, vomiting, or difficulty in swallowing or breathing. Patients
should not take bulks within 3 hours of any medication with a narrow
therapeutic index (NTI), such as digitalis or warfarin. Bulks include
psyllium (e.g., Metamucil, Konsyl Powder, Hydrocil), calcium
polycarbophil (e.g., FiberCon, Konsyl Fiber Tablets), and
methylcellulose (e.g., Citrucel).7
Stool Softeners: Docusate has a surfactant effect that softens stool and promotes a bowel movement in 12 to 72 hours.7
It has few adverse reactions. Patients taking medications with NTIs
(e.g., digitalis, warfarin) should not use it, and if it is
coadministered with mineral oil, the patient can experience systemic
lipid granulomatosis. Products include calcium docusate (e.g., Surfak)
and sodium docusate (e.g., Colace, Phillips’ Stool Softener, Dulcolax
Saline Laxatives: These laxatives osmotically draw water into the bowel to promote a watery bowel movement within 6 to 8 hours.7
Patients should be advised to ingest adequate water (i.e., 8 oz) with
them to prevent dehydration. Oral sodium phosphate/biphosphate was
discontinued in 2008 for causing acute kidney injury, leaving
magnesium-containing products as the only “salines.” They include
magnesium citrate, which is occasionally used as a presurgical bowel
preparation agent. Another example is magnesium hydroxide, also known as
Milk of Magnesia in suspension form. Magnesium should be avoided in
patients with adynamic ileus, severe diarrhea, abdominal trauma,
intestinal obstruction, heart block, or renal failure, and in patients
who require prolonged catharsis.7
Mineral Oil: Mineral
oil produces bowel movements in 6 to 8 hours by virtue of its lubricant
effect, but the precautions to its use cause it to be a poor choice.7
They include accidental aspiration causing lipid pneumonia, leakage of
oily feces, malabsorption of oil-soluble vitamins (i.e., A, D, E, K),
and hemorrhagic disease of the newborn if taken in pregnancy (due to
vitamin K deficiency).7
Stimulant Laxatives: As
is the case with mineral oil, the potential dangers of stimulant
laxatives outweigh their benefit, especially in light of the fact that
there are far safer choices.7 Stimulant laxatives cause
intestinal straining, emesis, abdominal discomfort, electrolyte
abnormalities, dehydration, and watery stools. Several stimulants have
been taken off of the market due to carcinogenicity (e.g., danthron,
aloe, casanthranol, phenolphthalein), but senna (e.g., ex-lax, Senokot),
bisacodyl (e.g., Dulcolax Tablets, Fleet Stimulant Laxative), and
castor oil remain.7
The drastic, nonphysiological action of stimulant laxatives leads to habituation.13
They empty the distal bowel, but their sustained action also forces the
patient to experience loose, watery bowel movements from stool that has
not yet reached the distal bowel. When the patient attempts to have a
bowel movement the next day, there are no results because that stool has
been prematurely evacuated under the drastic action of the stimulant.
However, the patient perceives the unsuccessful bowel movement as
another case of constipation and incorrectly takes an additional dose of
stimulant. Even though the products are labeled to cease use in 7 days,
patients may ignore the warning and take them for months or years. For
this reason, pharmacists who suspect habituation should urge patients to
discontinue the stimulant and attempt to bulk the stools with a fiber
replacement product. Patients who remain constipated upon
discontinuation should be advised to visit a physician to investigate
whether long-term stimulant use has caused permanent damage to the
Pharmacists should be aware of pregnant women who wish to
purchase castor oil to hasten the birth of an “overdue” baby, based on
advice on the Internet or from friends or relatives. This practice has
resulted in the death of the mother and child.7 Pharmacists must advise the mother to speak to her physician about her desire to initiate labor before the child is due.
What Is Constipation?
Many people have the idea that a daily bowel movement is
necessary to remain healthy. If they fail to attain this goal, they may
decide they need to force it with the aid of a stimulant laxative. The
reality is far more complicated, as “normal” varies from person to
person. It is true that some people normally have a single bowel
movement daily. But physicians define the normal range of bowel
movements as 3 daily to 3 weekly.
Constipation can then be seen as less than your own normal
frequency, especially if there are fewer than 3 bowel movements per
week. Further, if the stools are harder, drier, or smaller than usual,
they become more difficult to eliminate, which are also signs of
constipation. You may have a bloated feeling, or a sensation of
discomfort in the abdomen caused by trapped feces and gas.
Preventing Constipation With Fiber
The most common cause of constipation is too little fiber
in the diet. Fiber comes from plants and has the ability to help the
residues of food remain soft as they pass through the stomach and
intestinal tract. Foods high in fiber include whole grains, corn, beans,
avocado, apples, and nuts. In addition to ingesting more fiber, you can
also drink plenty of fluids to help the fibrous materials pass through
the digestive tract smoothly.
If eating foods with fiber is a challenge, consider
nonprescription fiber supplements such as psyllium (found in Metamucil,
Konsyl powder, and Hydrocil products), methylcellulose (Citrucel
products), or calcium polycarbophil (FiberCon caplets, Konsyl tablets).
You should read and follow all directions for these products. Speak to
your pharmacist for assistance with fiber supplements.
Being physically active seems to help prevent
constipation, although the reason is unclear. It is helpful to engage in
a daily bout of gentle activity such as walking. Ensure that your body
can tolerate the exercise you choose, and speak with your physician for
Heed the Urge to Have a Bowel Movement
When the urge to have a bowel movement hits, it is important to respond. This helps ensure that
you will continue to perceive that useful signal. People ignore
the urge for several reasons, such as being away from home or not
wanting to use an unfamiliar toilet. The problem is that continually
ignoring this urge will cause it to disappear.
Treatment of Constipation
Constipation is caused by many problems, including
potentially dangerous medical conditions and medications you may be
taking. For this reason, you should not self-treat constipation for more
than 7 days. There are many other precautions on the labels of
laxatives that you should read and understand before use.
It is important to Consult Your Pharmacist for
assistance with these products. Your pharmacist is specifically trained
in helping you choose the appropriate products for preventing and
Remember, if you have questions, Consult Your Pharmacist.
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12. MiraLAX product label. MSD Consumer Care, Inc. www.miralax.com/pdf/MiraLAX_ProductLabel.pdf. Accessed October 19, 2013.
13. Senna. MedlinePlus. www.nlm.nih.gov/medlineplus/druginfo/meds/a601112.html. Accessed October 19, 2013.
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