Brand Names: Coumadin,
Drug Class: Anticoagulant
Available in: Tablets,
Available Without a Prescription? No
Available as a Generic? Yes
reaction (wheezing, breathing difficulty, hives, or swelling
of lips, tongue, and throat); bleeding into skin and soft tissue;
from nose, gastrointestinal tract, urinary tract, or uterus; severe infection;
excessive or unexpected menstrual bleeding; black vomit; bruises or purple
marks on skin. Consult your doctor immediately if you experience any
of these side effects.
Common: No common
side effects have been reported.
Less Common: Loss
of appetite, unusual weight loss, nausea, vomiting, skin rash,
To prevent blood clot formation in people suffering
from heart, lung, and blood vessel disorders that could lead
to heart attack, stroke, or other problems.
How the Drug Works
Warfarin blocks the action of vitamin K, a compound
necessary for blood clotting.
Adults: To start, 10 to 15 mg daily, taken
once a day. Long-term, usually 2 to 10 mg per day, taken once
a day. Children: The dose must be determined by a pediatrician.
It should be taken at the same time every day.
Onset of Effect
36 to 48 hours.
Duration of Action
24 to 96 hours.
Warfarin can be taken with liquid or food.
Store in a tightly sealed container away from heat
and direct light.
If You Miss a Dose
If you miss a dose, take it as soon as you remember,
unless it is almost time for the next dose. In that case, skip
the missed dose and go back to your regular schedule. Do not
double the next dose.
Stopping the Drug
Take it as prescribed for the full treatment period,
even if you begin to feel better before the scheduled end of
therapy. The decision to stop taking the drug should be made
by your doctor.
Regular tests of prothrombin time (a simple test
that measures the time it takes for one stage of blood coagulation
to occur) are needed when taking this drug. Your doctor may also
take stool and urine samples periodically to check for the presence
Over 60: Adverse reactions
may be more likely and more severe in older patients.
Driving and Hazardous Work: Avoid
if you have blurred vision or feel dizzy. Avoid activities that
could cause injury.
Alcohol: Use with
caution. Alcohol can increase or decrease the effect of warfarin.
Usually, consume no more than one drink a day.
may cause birth defects. Do not use during pregnancy.
Breast Feeding: Warfarin
passes into breast milk. Do not use while nursing.
Infants and Children: Not
recommended for children under 18.
gums, uncontrolled nosebleeds, blood in the urine
What to Do: Discontinue
the medication and call your doctor, emergency medical services
(EMS), or the nearest poison control center right away.
Consult your doctor for specific advice if you
are taking steroid drugs, acetaminophen, allopurinol, aminogluthemide,
antibiotics, antiarrhythmic heart drugs, androgens, antacids,
antifungal drugs, antihistamines, aspirin, antidiabetic drugs,
disulfiram, a non-steroidal anti-inflammatory drug (NSAID), barbiturates,
benzodiazepine tranquilizers, calcium supplements, chloramphenicol,
or any cholesterol-lowering drugs.
Avoid green, leafy vegetables and other foods that
are rich in vitamin K (liver, broccoli, cauliflower, kale, spinach,
and cabbage). Intake of too much vitamin K can override the anticlotting
effect of warfarin and render the drug useless. Conversely, certain
substances can interfere with the absorption of vitamin K so
much that normal, healthy clotting (necessary for wounds to heal)
is impaired. Megadoses of vitamin E can do this, as can fish
oil supplements and foods high in omega-3 fatty acids. These
substances can enhance the effect of anticlotting drugs so much
that a tendency to hemorrhage may result.
Consult your doctor about taking warfarin if you
have high blood pressure, diabetes, serious liver or kidney disease,
or a severe allergy.
From The Johns
Hopkins Consumer Guide to Drugs. You can order
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