Understanding and treating an irritable bowel
and treating an irritable bowel
Irritable bowel syndrome significantly
disrupts life for the women who have it. The
good news is that we’re finding better
ways to control it.
Irritable bowel syndrome (IBS)
affects an estimated 24 million people in the
United States. Experts aren’t sure why,
but 70% of sufferers are women.
IBS causes recurrent episodes
of constipation or diarrhea (or alternating
bouts of each) along with cramps, bloating,
and gas. For many, “irritable” vastly
understates the impact of IBS. Symptoms often
interfere with work and other activities. Some
women hesitate to leave their homes because
they’re embarrassed or don’t want
to be very far from a bathroom.
an irritable bowel
There is no test for IBS.
A clinician familiar with this condition can
usually make a diagnosis just by talking with
you and performing a physical exam. She or
he will look for specific symptoms (see “Criteria
for diagnosing IBS”) and may order routine
blood and stool tests and check for lactose
intolerance. She or he will also try to rule
out other causes such as a thyroid disorder,
endometriosis, and other bowel diseases. In
some cases, clinicians may recommend a sigmoidoscopy
or colonoscopy to examine the colon.
for diagnosing IBS
IBS is a functional
bowel disorder — that is, there
is no known disease or structural abnormality
behind its symptoms. An IBS diagnosis
requires the presence of abdominal
pain or discomfort for 12 or more weeks
(not necessarily consecutive) in the
past 12 months, accompanied by at least
two of the following:
- relief of abdominal discomfort
- a change in the frequency of bowel
- a change in stool appearance or
These symptoms also
- abnormal stool frequency (more
than three times per day or less
than three times per week)
- abnormal stool form or consistency
- abnormal stool passage (straining,
urgency, feeling of incomplete evacuation)
- passage of mucus
- bloating or a feeling of abdominal
causes the symptoms?
Some experts suspect disturbances
in the nerves or muscles in the gut cause IBS.
Others believe that abnormal processing of
gut sensations in the brain may be responsible.
For example, well-known research indicates
that people with IBS have an unusually heightened
awareness of bowel sensations. Some patients
may have irregularities in the muscle activity
of the colon. And research suggests that a
bout with an intestinal virus may set off IBS,
particularly when a stressful event follows
An emerging theory focuses
on the neurotransmitter serotonin. Neurotransmitters
are chemicals that transmit messages between
nerve cells. Most of us have heard about the
relationship between depression and serotonin
in the brain, but the gut also produces serotonin,
which in turn acts on nerves in the digestive
tract. Some research suggests that IBS patients
who suffer mainly from diarrhea may have increased
serotonin levels in the gut, while those with
constipation-predominant IBS have decreased
Emotional factors also play
a role. For example, stress often worsens symptoms,
and studies suggest that cognitive behavioral
therapy, relaxation therapy, and hypnotherapy
can help relieve pain and symptoms. Stress
management, diet, and exercise have also proven
constipation, diarrhea, and gas
Because there is no cure for
IBS, the goal of treatment is to control symptoms.
agents (fiber, bran, and psyllium laxatives)
help by moving waste through the intestines;
however, they may not be useful for pain or
diarrhea, and can cause gas and bloating. When
using bulking agents, start slowly and gradually
increase your intake. Be sure to drink plenty
While there are no good data,
most doctors think laxatives can be safe and
effective when used judiciously. Stimulant
laxatives (bisacodyl and glycerol) may cause
abdominal cramping. Laxative herbal teas are
also available; start with a weak brew and
work up to the strength that works for you.
reduces intestinal muscle contractions and
fluid secretion in the gut. Studies show that
it helps relieve diarrhea, but not pain. It
may not be a good choice for women whose symptoms
fluctuate between constipation and diarrhea.
A lower-dose form of loperamide is sold over
the counter as Imodium. Lomotil (diphenoxylate
and atropine) is a prescription drug also used
to treat IBS-related diarrhea.
Gas and bloating. Simethicone-based
products (Gas-X, Maalox), charcoal, and alpha-galactosidase
(Beano) aren’t very effective, and no
prescription drugs have proven useful. The
best approach is to avoid the foods that trigger
gas and bloating. Common offenders include
beans, pretzels, bananas, dairy products, carbonated
beverages, and raw fruits and vegetables (particularly
cabbage, cauliflower, and broccoli). Fructose
(a common sweetener) and sorbitol (an artificial
sweetener) can also cause bloating and diarrhea.
Antispasmodics relax the muscle
of the stomach and intestines. These drugs
help relieve abdominal pain, but their benefits
for constipation and diarrhea are uncertain.
Antispasmodics available in the United States
include dicyclomine (Bentyl) and hyoscyamine
(Anaspaz, Cystospaz, others). Side effects
include dry mouth, sweating, blurred vision,
dizziness, constipation, bloating, urinary
problems, headaches, and palpitations. Some
women find peppermint oil helpful as an antispasmodic,
but it can cause heartburn because it also
relaxes the band of muscle that helps keep
stomach contents from backing up into the esophagus.
Prokinetic agents increase
smooth muscle activity and so may help relieve
bloating or constipation. Metoclopramide (Reglan)
and newer drugs such as tegaserod (Zelnorm)
have prokinetic action.
Low doses of tricyclic antidepressants
such as amitriptyline (Elavil) or nortriptyline
(Aventyl, Pamelor) taken at bedtime appear
to alleviate abdominal pain. Some studies suggest
that these drugs are most helpful for diarrhea-predominant
IBS. Side effects include fatigue, sleepiness,
dry mouth, and constipation, which can be severe.
It isn’t clear exactly how tricyclics
help, but they may reduce nerve sensitivity.
Selective serotonin reuptake inhibitor antidepressants
have fewer side effects, but haven’t
proved useful in IBS. However, they may be
beneficial when depression or a mood disorder
pros and cons of probiotics
Probiotics are live
bacteria taken in capsule or powder
form (or in yogurt). They may help
with intestinal troubles by restoring
the balance of bacteria in the intestine,
and possibly by affecting the immune
A number of small
studies, as well as anecdotal reports,
suggest that probiotics improve IBS
symptoms for some people. However,
data on their safety and effectiveness
You can find probiotic
supplements in grocery stores, health
food stores, and pharmacies and through
Web sites. If you’re interested
in trying one, talk with your doctor.
She or he may be able to offer some
One of the most promising
approaches to IBS treatment involves medications
that alter the action of serotonin in the colon.
These drugs act on the serotonin receptors
on intestinal nerves — specifically serotonin-3
(5HT3) and serotonin-4 (5HT4)
Drugs known as 5HT3 receptor
antagonists inhibit the action of serotonin
in the gut. Alosetron (Lotronex), the first
5HT3 receptor antagonist developed
for IBS, had a rocky start. FDA-approved in
2000, Lotronex relieved symptoms for many women
with diarrhea-predominant IBS. (The drug doesn’t
work in men.) Constipation was the most common
side effect. Several months later, reports
of severe complications of constipation that
resulted in 44 hospitalizations and 5 deaths
prompted the manufacturer to withdraw the drug
from the market. These complications included
intestinal blockages, extreme inflammation
and distention of the large intestine, and
compromised blood flow to the colon (ischemic
It was a tremendous disappointment
for the many women who benefited from Lotronex.
Lobbying by patients and doctors eventually
brought this drug back to market in 2002, but
only under a tightly controlled prescribing
program (for more information, go to www.lotronex.com).
A 5HT3 antagonist (cilansetron)
is now under study. Preliminary data suggest
that this drug offers benefits to both men
and women with IBS.
The 5HT4 agonists
have the opposite effect of 5HT3 antagonists.
Like Lotronex, the 5HT4 agonist
tegaserod (Zelnorm) greatly improves symptoms,
but this time for women with constipation-predominant
IBS. It, too, is effective only in women. Tegaserod
speeds up movement of bowel contents through
the colon and reduces sensitivity to intestinal
nerve stimulation. As you’d expect, diarrhea
is the most common side effect.
Many researchers believe that
the key to better IBS treatment lies in tweaking
the neurotransmitters and hormones related
to gastrointestinal motility and sensation.
Several newer and more specific compounds are
under investigation, including muscarinic-3
receptor antagonists, neurokinin receptor antagonists,
and opiate agonists.
As more targeted medications
become available, physicians will be able to
tailor treatment to individual women. In the
meantime, if you have IBS, you’ll want
to collaborate with a clinician who has experience
treating IBS and who can help you find the
best treatment plan for you.
The New Eating
Right for a Bad Gut, by James
Scala (Dimensions, 2000).
for Functional Gastrointestinal Disorders,
888-964-2001 (toll free), www.iffgd.org
The Sensitive Gut, a
Harvard Health Publications special
health report. To obtain a copy, go
1 in 4 people has frequent gastrointestinal (GI) problems that can severely
disrupt a normal lifestyle. In The Sensitive Gut Report our
doctors describe how to help prevent and treat common and not-so-common
digestive problems ranging from heartburn to IBS. Read more »