Encyclopedia of Health and Medicine

antiemetic medications 13
CAFFEINE consumption, FOOD-BORNE ILLNESSES, or
viral INFECTION (GASTROENTERITIS or ENTERITIS). These
circumstances tend to resolve themselves within a
few days, which may be briefer than the actions of
many antidiarrheal medications.
Taking an antidiarrheal product may result in
rebound CONSTIPATION. However, diarrhea more
significantly interferes with daily activities than
does constipation, and many people opt to take
medications to slow or stop it. It is important to
drink extra fluids when taking antidiarrheal medications,
to replace fluids lost with the diarrhea as
well as to maintain adequate hydration of the gastrointestinal
tract to prevent rebound constipation
from developing. Some antidiarrheal medications
are available over the counter and others require a
doctor’s prescription.
Doctors sometimes prescribe anticholinergic
medications, which act on the NERVOUS SYSTEM to
slow gastrointestinal function, for severe diarrhea.
However, these medications have numerous
actions throughout the body, and doctors tend to
reserve them for use when other antidiarrheal
medications are ineffective. Opiate NARCOTICS such
as paregoric and codeine are effective for slowing
gastrointestinal motility. Attapulgite, pectin, and
kaolin are natural substances that absorb fluid.
Though typically perceived as LAXATIVES, bulking
agents such as psyllium and methylcellulose also
absorb water and can help restore normal bowel
function.
Antidiarrheal medications are most effective for
controlling outbreaks of diarrhea such as may
occur with IRRITABLE BOWEL SYNDROME (IBS), INFLAM-
MATORY BOWEL DISEASE (IBD), and MALABSORPTION.
Antidiarrheal medications are also effective for
treating antibiotic-induced diarrhea that does not
end when the antibiotic therapy ends. Remedies
such as taking lactobacillus or eating plain yogurt
may help restore normal BACTERIA to the gastrointestinal
tract.
The most frequent complication of antidiarrheal
medications is rebound constipation. A rare
but serious complication that can occur when taking
antidiarrheal medications that slow gastrointestinal
motility is TOXIC MEGACOLON, in which the
colon becomes vastly dilated and flaccid and the
flow of the intestinal content stops. Antidiarrheal
medications also can mask conditions that require
medical attention. For most people, occasional use
of over-the-counter antidiarrheal medications provides
prompt relief of diarrhea with few complications.
See also ANTACIDS; ANTIEMETIC MEDICATIONS; FIBER
AND GASTROINTESTINAL HEALTH.
antiemetic medications Medications that relieve
NAUSEA and VOMITING (known clinically as emesis).
The most commonly used are anticholinergic
medications and antihistamine MEDICATIONS, which
suppress the vestibular system mechanisms that
cause vomiting. Many antihistamine products are
available over the counter. Doctors may recommend
or prescribe these medications to treat nausea
related to VERTIGO, MÉNIÈRE’S DISEASE,
LABYRINTHITIS, and other disorders of the inner EAR
and vestibular system, and to help prevent motion
sickness. Both anticholinergics and antihistamines
can cause drowsiness and dry MOUTH.
A classification of powerful antiemetics, the 5-
HT3 RECEPTOR ANTAGONIST MEDICATIONS, became
available in the 1990s. Doctors prescribe these
medications, such as dolasetron and ondansetron,
primarily to treat nausea and vomiting resulting
from RADIATION THERAPY, CHEMOTHERAPY, and surgery.
These medications work by blocking serotonin
from reaching receptors in the
gastrointestinal system and may have neurologic
side effects such as Parkinson-like symptoms.
Over-the-counter products to treat nausea
include bismuth subsalicylate (Pepto-Bismol) and
cola syrup, both of which are effective for relieving
mild nausea and vomiting with viral INFECTION
(such as GASTRITIS and GASTROENTERITIS). Pharmacies
also sell a commercial preparation of phosphorated
carbohydrate solution, similar to cola syrup,
called Emetrol. Cola drinks allowed to go “flat”
have the same antinausea effect. These substances
act to soothe the inner lining of the stomach. GIN-
GER also has a calming action on the stomach and
can provide relief through drinking flat ginger ale
(brands that contain ginger, not just ginger flavoring)
or eating small pieces of fresh ginger root.
Treatment for nausea and vomiting also targets
any underlying conditions or causative circumstances.
See also ACUPUNCTURE; MORNING SICKNESS; NEURO-
TRANSMITTER.