Compare Coumadin vs. Heparin

Head-to-head comparisons of medication uses, side effects, ratings, and more.



Prevents blood clots. Coumadin (Warfarin) is an old, cheap, and effective medicine to prevent blood clots, but it requires some monitoring, dose adjustments, and even lifestyle changes.Prevents blood clots. Heparin is a good anticoagulant that prevents blood clots. However, you'll need to get frequent blood tests to make sure it's working well.
Find lowest prices
Powered by GoodRxSave on your next prescription. Be sure you’re getting the lowest price for your medication, even if you have insurance.
Loading pricing data...
Reviews & ratings
Filter group. All currently selected
Filter group. All currently selected
Reviews for Coumadin (Warfarin)
of people say Coumadin (Warfarin) is worth it
say it works well
say it's a big hassle
512 reviews

Not enough reviews for this drug. Help someone out, leave a review!

Side effects

The Coumadin FDA package insert doesn’t have numbers about how common side effects are.

More about Coumadin side effects »

We haven’t found good data for Heparin side effects.

FDA side effect reports for Heparin »
How it works
Coumadin (Warfarin) is an anticoagulant blood thinner. It lowers chemicals called clotting factors so that it's harder for your body to form blood clots.Heparin is an anticoagulant that binds with proteins and platelets to stop blood clots from being made and traveling to the brain, heart, and lungs.
Type of medication
Vitamin K antagonist
Prescription only
Prescription only
Available as
  • Pill
  • Injection
Used for (click to learn more)
Risk factors for serious side effects
  • Dose too high
  • Age greater than 65
  • History of gastrointestinal bleeding
  • High blood pressure
  • Kidney or liver problems
  • Drug interactions
  • Change in lifestyle or diet
  • Illnesses
  • Alcohol
  • Certain genetic makeup
    • Women of childbearing age
    Detailed Coumadin (Warfarin) risks & warnings »
    • History of bleeding problems
    • Severe high blood pressure
    • Older age
    • Heparin-induced thrombocytopenia
    Detailed Heparin risks & warnings »
    Pregnancy category
    XFDA pregnancy category (Unsafe)

    Research studies with real people or animals found harmful effects on unborn babies. If you’re pregnant, the risks to your unborn baby outweigh the benefits.

    See the FDA package insert
    CFDA pregnancy category (Weigh risks vs. benefits)

    Research studies with animals found harmful effects on unborn babies. It hasn’t been properly studied in humans. The benefits might outweigh the risks even if you’re pregnant. Talk with your doctor.

    See the FDA package insert
    • Many lifestyle factors can affect how well warfarin works, such as diet, alcohol, and activity level, so it's important that you try to stay consistent with your behaviors.
    No specific alcohol-related info.
    • Eat foods containing consistent amounts of Vitamin K.
    No specific food-related info.
    Kidneys and liver
    No specific kidneys and liver-related info.No specific kidneys and liver-related info.
    No specific sex-related info.No specific sex-related info.
    No specific sleep-related info.No specific sleep-related info.
    No specific weight-related info.No specific weight-related info.
    Upsides and benefits
    • Oral blood-thinning medicine that prevents blood clots from forming or getting bigger.
    • Prevents complications of blood clots that can cause extreme discomfort or death. Examples include stroke (blood clots in the brain), pulmonary embolism (blood clots in the lungs causing trouble breathing), or deep vein thrombosis (blood clots in the legs causing pain and blood vessel damage).
    • Has an antidote, Vitamin K, in case of a major accidental bleeding.
    • Coumadin (Warfarin) has been around for a long time, so we know a lot about how well it works and what the risks are.
    • It's dirt cheap.
    • Safe to use in pregnancy and if you're breast feeding.
    • There are other medications that can help stop unexpected bleeding while taking Heparin.
    • Available as a generic medication.
    • Usually used in the hospital, but can be given at home too.
    Downsides and risks
    • Raises your risk of bleeding and bruising.
    • Requires routine blood testing (called an INR) to see how well the medicine is working for you and to make the dose just right for you.
    • Many lifestyle factors can affect how well warfarin works, such as diet, alcohol, and activity level, so it's important that you try to stay consistent with your behaviors.
    • Lots of interactions with other drugs or supplements. Always check with your doctor or pharmacist before starting any new meds.
    • You'll need to get labs/blood draws done on a regular basis to make sure the drug is working and to make sure you don't get unexpected side effects.
    • You can be at higher risk for bleeding or clotting while taking Heparin compared to other anticoagulants.
    Tips from our pharmacists for people taking the medication
    • Thins your blood to prevent clots from forming or getting bigger. Doesn't break up existing clots.
    • The amount you need depends on your diet, other medical problems, and genes.
    • Take it exactly as instructed.
    • Can raise your risk of bleeding or bruising.
    • Requires regular blood tests to get your dose right.
    • Interacts with a lot of medicines and supplements. Don't start any new meds without talking to your doctor.
    • Eat foods containing consistent amounts of Vitamin K.
    • Tell your doctor immediately if you fell or if you have unusual bleeding, bruising, swelling, or changes in vision and coordination.
    • Get a medical bracelet so that people know you're on a blood thinner during an emergency situation.
    • Make sure to change where you inject Heparin every time.
    • Don't take aspirin or other anti-inflammatory medications without talking to your doctor first.
    • You will have to do regular blood draws or labs to make sure that Heparin is working for you.
    Learn more
    More about CoumadinSide effectsReviews & ratingsAlternativesFDA package insert
    More about HeparinSide effectsReviews & ratingsAlternativesFDA package insert