Dr. MJ Bazos MD,
Effects of Medicines on the Adult Digestive System
Many medicines taken by mouth may affect the
digestive system. These medicines include prescription (those ordered by a
doctor and dispensed by a pharmacist) and nonprescription or over-the-counter
(OTC) products. A glossary at the end of this fact sheet describes some common
prescription and nonprescription medicines discussed below that may affect the
medicines usually are safe and effective, harmful effects may occur in some
people. OTC's typically do not cause serious side effects when taken as directed
on the product's label. It is important to read the label to find out the
ingredients, side effects, warnings, and when to consult a doctor.
Always talk with your doctor before
taking a medicine for the first time and before adding any new medicines to
those you already are taking. Tell the doctor about all other medicines
(prescription and OTC's) you are taking. Certain medicines taken together may
interact and cause harmful side effects. In addition, tell the doctor about any
allergies or sensitivities to foods and medicines and about any medical
conditions you may have such as diabetes, kidney disease, or liver disease.
Be sure that you understand all
directions for taking the medicine, including dose and schedule, possible
interactions with food, alcohol, and other medicines, side effects, and
warnings. If you are an older adult read all directions carefully and ask your
doctor questions about the medicine. As you get older, you may be more
susceptible to drug interactions that cause side effects.
People with a food intolerance such as
gluten intolerance should make sure their medicines do not contain fillers or
additives with gluten. Check with your doctor if you have any questions or
concerns about your medicines. Follow the doctor's orders carefully, and
immediately report any unusual symptoms or the warning signs described below.
Some people have difficulty swallowing
medicines in tablet or capsule form. Tablets or capsules that stay in the
esophagus may release chemicals that irritate the lining of the esophagus. The
irritation may cause ulcers, bleeding, perforation (a hole or tear), and
strictures (narrowing) of the esophagus. The risk of pill-induced injuries to
the esophagus increases in persons with conditions involving the esophagus, such
as strictures, scleroderma (hardening of the skin), achalasia (irregular muscle
activity of the esophagus, which delays the passage of food), and stroke.
Some medicines can cause ulcers when
they become lodged in the esophagus. These medicines include aspirin, several
antibiotics such as tetracycline, quinidine, potassium chloride, vitamin C, and
•Pain when swallowing food or liquid.
•Feeling of a tablet or capsule "stuck" in
•Dull, aching pain in the chest or
shoulder after taking medicines.
•Swallow tablets or capsules while you are
in an upright or sitting position.
•Before taking a tablet or capsule,
swallow several sips of liquid to lubricate the throat, then swallow the tablet
or capsule with at least a full glass (8 ounces) of liquid.
•Do not lie down immediately after taking
medicines to ensure that the pills pass through the esophagus into the stomach.
•Tell your doctor if painful swallowing
continues or if pills continue to stick in the throat.
The lower esophageal sphincter (LES)
muscle is between the esophagus and the stomach. The muscle allows the passage
of food into the stomach after swallowing. Certain medicines interfere with the
action of the sphincter muscle, which increases the likelihood of backup or
reflux of the highly acidic contents of the stomach into the esophagus.
Medicines that can cause esophageal reflux
include nitrates, theophylline, calcium channel blockers, anticholinergics, and
birth control pills.
•Heartburn or indigestion.
•Sensation of food coming back up into the
•Avoid foods and beverages that may worsen
reflux, including coffee, alcohol, chocolate, and fried or fatty foods.
•Cut down on, or preferably quit, smoking.
•Do not lie down immediately after eating.
One of the most common drug-induced
injuries is irritation of the lining of the stomach caused by nonsteroidal
anti-inflammatory drugs (NSAIDs).
can irritate the stomach by weakening the ability of the lining to resist acid
made in the stomach. Sometimes this irritation may lead to inflammation of the
stomach lining (gastritis), ulcers, bleeding, or perforation of the lining.
In addition, you should be aware that
stomach irritation may occur without having any of the symptoms below.
Older people are especially at risk
for irritation from NSAIDs because they are more likely to regularly take pain
medicines for arthritis and other chronic conditions. Also at risk are
individuals with a history of peptic ulcers and related complications or
gastritis. These individuals should tell their doctor about any of these
previous conditions. Special medicines may be needed to protect the stomach
•Severe stomach cramps or pain or burning
in the stomach or back.
•Black, tarry, or bloody stools.
•Severe heartburn or indigestion.
•Use coated tablets, which may lessen
•Avoid drinking alcoholic beverages while
•Take medicines with a full glass of water
or milk or with food, which may reduce irritation.
Delayed Emptying of the Stomach
Some medicines cause nerve and muscle
activity to slow down in the stomach. This slowing down causes the contents of
the stomach to empty at a slower rate than normal.
Drugs that may cause this delay include
anticholinergics and drugs used to treat Parkinson's disease and depression.
•Feeling of fullness.
•Vomiting of food eaten many hours
•Pain in midabdomen.
•Heartburn or indigestion.
•Sensation of food coming back up into the
•Eat frequent, small meals.
•Do not lie down for about 30 minutes
•Tell your doctor if symptoms continue.
Your doctor may consider changing your dosage of the medicine or trying a new
Constipation can be caused by a
variety of medicines. These medicines affect the nerve and muscle activity in
the large intestine (colon). This results in the slow and difficult passage of
stool. Medicines also may bind intestinal liquid and make the stool hard.
Medicines that commonly cause
constipation include antihypertensives, anticholinergics, cholestyramine, iron,
and antacids that contain mostly aluminum.
•Constipation that is severe or
disabling or that lasts several weeks.
•Drink plenty of fluids.
•Eat a well-balanced diet that includes
whole grains, fruits, and vegetables.
•Take laxatives only under a doctor's
Diarrhea is a common side effect of
many medicines. Diarrhea is often caused by antibiotics, which affect the
bacteria that live normally in the large intestine.
Antibiotic-induced changes in intestinal
bacteria allow overgrowth of another bacteria, Clostridium difficile (C.
difficile), which is the cause of a more serious antibiotic-induced
The presence of C.
difficile can cause colitis, an inflammation of the intestine in which the bowel
"weeps" excess water and mucus, resulting in loose, watery stools. Almost any
antibiotic may cause C. difficile-induced diarrhea, but the most common are
ampicillin, clindamycin, and the cephalosporins. Antibiotic-induced colitis is
treated with another antibiotic that acts on C. difficile.
Diarrhea also can be a side effect of
drugs that do not cause colitis but that alter the movements or fluid content of
the colon. Colchicine is a common cause of drug-induced diarrhea.
Magnesium-containing antacids can have the effect of laxatives and cause
diarrhea if overused. In addition, the abuse of laxatives may result in damage
to the nerves and muscles of the colon and cause diarrhea.
•Blood, mucus, or pus in the stool.
•Pain in the lower abdomen.
•If diarrhea lasts for several
days, consult your doctor.
The liver processes most medicines
that enter the bloodstream and governs drug activity throughout the body. Once a
drug enters the bloodstream, the liver converts the drug into chemicals the body
can use and removes toxic chemicals that other organs cannot tolerate. During
this process, these chemicals can attack and injure the liver.
Drug-induced liver injury can resemble
the symptoms of any acute or chronic liver disease. The only way a doctor can
diagnose drug-induced liver injury is by stopping use of the suspected drug and
excluding other liver diseases through diagnostic tests. Rarely, long-term use
of a medicine can cause chronic liver damage and scarring (cirrhosis).
Medicines that can cause severe liver
injury include large doses of acetaminophen (and even in small doses when taken
with alcohol), anticonvulsants such as phenytoin and valproic acid, the
antihypertensive methyldopa, the tranquilizer chlorpromazine, antituberculins
used to treat tuberculosis such as isoniazid and rifampin, and vitamins such as
vitamin A and niacin.
(for liver injury)
•Abdominal pain and swelling.
•Jaundice (yellow eyes and skin, dark
•Nausea or vomiting.
•If you have ever had a liver disease or
gallstones, you should discuss this with your doctor before taking any medicines
that may affect the liver or the gallbladder.
•Take these medicines only in the
prescribed or recommended doses.
Glossary of Medicines
The following glossary is a guide to
medicines used to treat many medical conditions. The glossary does not include
all medicines that may affect the digestive system. If a medicine you are taking
is not listed here, check with your doctor.
Acetaminophen relieves fever and pain
by blocking pain centers in the central nervous system.
Examples of brand names include Tylenol,
Panadol, and Datril.
Antacids relieve heartburn, acid
indigestion, sour stomach, and symptoms of peptic ulcer. They work by
neutralizing stomach acid.
hydroxide antacids include Alu-Tab and Amphojel; calcium carbonate antacids
include Tums, Alka Mints, and Rolaids Calcium Rich; magnesium antacids include
Mylanta and Maalox.
Antibiotics destroy or block the
growth of bacteria that cause infection.
Hundreds of antibiotics are available,
including penicillins (Amoxil, Amcil, and Augmentin), clindamycin,
cephalosporins (Keflex and Ceclor), tetracyclines (Minocin, Sumycin, and
Vibramycin), quinolones (Cipro), and sulfa drugs (Bactrim).
This class of medicines affects the
nerve cells or nerve fibers and includes drugs for depression, anxiety, and
Examples of anticholinergics
include propantheline (Pro-banthine) and dicyclomine (Bentyl). Examples of
antidepressants include amitriptyline (Elavil and Endep), and nortriptyline
(Aventyl and Pamelor).
relieving the symptoms of Parkinson's disease also are in this category.
Examples include levodopa (Dopar) and carbidopa and levodopa combination
These medicines control epilepsy and
other types of seizure disorders. They act by lessening overactive nerve
impulses in the brain.
Examples of this
class of medicines include phenytoin (Dilantin) and valproic acid (Dalpro).
Antihypertensives lower high blood
pressure. They act by relaxing blood vessels, which makes blood flow more
Examples of antihypertensives
include methyldopa (Aldomet) and clonidine hydrochloride (Catapres).
These drugs for tuberculosis limit the
growth of bacteria or prevent tuberculosis from developing in people who have a
positive tuberculin skin test.
include INH, Dow-Isoniazid, Rifadin, and Rimactane.
Calcium Channel Blockers
These medicines for angina (chest
pain) and high blood pressure affect the movement of calcium into the cells of
the heart and blood vessels, relax blood vessels, and increase the flow of blood
and oxygen to the heart.
calcium channel blockers include diltiazem (Cardizem), nifedipine (Procardia),
and verpamil (Isoptin).
This tranquilizer relieves anxiety or
Examples of brand names include
Thorazine and Ormazine.
This medicine eases the inflammation
from gout and prevents attacks from recurring.
Iron is a mineral the body needs to
produce red blood cells. Iron supplements are used to treat iron deficiency or
Many forms of laxatives are available
for relieving constipation.
names of laxatives include Phillips' Milk of Magnesia, Citroma, Epsom salts,
Correctol, and ExLax.
These drugs for angina (chest pain)
relax blood vessels and increase the flow of blood to the heart.
Examples of generic and brand names
include isosorbide dinitrate (Iso-Bid and Isonate) and nitroglycerin (Nitro-Bid
anti-inflammatory drugs (NSAIDs)
drugs block the body's production of prostaglandins, substances that mediate
pain and inflammation. NSAIDs relieve the pain from chronic and acute
inflammatory conditions, including arthritis and other rheumatic conditions, and
pain associated with injuries, bursitis, tendinitis, and dental problems. NSAIDs
also relieve pain associated with noninflammatory conditions.
Generic and brand names of NSAIDs include
aspirin (Bayer and Bufferin), ibuprofen (Advil, Nuprin, and Motrin), tometin
(Tolectin), naproxen (Naprosyn), and piroxicam (Feldene).
Potassium is a vital element in the
body. Potassium supplements help prevent and treat potassium deficiency in
people taking diuretics.
This medicine often is used to correct
Brand names of
quinidine include Quinalan and Quiniglute.
This medicine eases breathing
difficulties associated with emphysema, bronchitis, and bronchial asthma. The
medicine works by relaxing the muscles of the respiratory tract, which allows an
easier flow of air into the lungs.
Examples of brand names include Theo-Dur,
Theophyl, and Bronkodyl.
Vitamins serve as nutritional
supplements in people with poor diets, in people recovering from surgery, or in
people with special health problems.
•Niacin helps the body break down
food for energy and is used to treat niacin deficiency and to lower levels of
fats and cholesterol.
•Vitamin A is
necessary for normal growth and for healthy eyes and skin.
•Vitamin C is necessary for healthy
function of cells.