Compare Coumadin vs. Aspirin

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.Relieves pain, fever, and inflammation. Protects your heart and thins blood. A low dose of Aspirin (81mg) every day can protect your heart, but it's not the best medicine to take for pain, swelling, or fever.
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Reviews & ratings
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Reviews for Coumadin (Warfarin)
of people say Coumadin (Warfarin) is worth it
say it works well
say it's a big hassle
512 reviews
Reviews for Aspirin
+15% vs. Coumadin (Warfarin)
13% vs. Coumadin (Warfarin)
+15% vs. Coumadin (Warfarin)
532 reviews
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 Aspirin side effects.

FDA side effect reports for Aspirin »
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.Aspirin is a salicylate and non-steroidal anti-inflammatory drug (NSAID). It blocks the inflammation process in your body, which relieves swelling and pain. It also prevents blood platelets from forming clots, which thins your blood.
Type of medication
Vitamin K antagonist
Prescription only
Pain reliever
Available as
  • Pill
  • Pill
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 »
    • Children 18 years or younger
    • Children recovering from viral infections
    • History of stomach bleeding or ulcers
    • Age 60 years or older
    • Taking Aspirin, NSAIDs, or blood thinners
    • Drinking more than 3 alcoholic beverages a day
    • Asthma
    • Rhinitis
    • Nasal polyps
    • Aspirin allergy
    • NSAID allergy
    • Women of childbearing age
    Detailed Aspirin 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
    NFDA pregnancy category (Unknown)

    The FDA hasn’t classified this medicine’s effects on unborn babies. Talk with your doctor about this medicine if you’re pregnant or planning on it.

    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.
    • Take with food to lower the chance of an upset stomach.
    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.
    • When taking low doses (81 mg) every day, Aspirin provides protection for your heart and prevents heart attacks and stroke.
    • Used in higher doses to relieve pain, swelling, and fever.
    • Available over-the-counter in drugstores by itself and in combination with other cold and flu medications.
    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.
    • Not a preferred medication for treating pain, swelling, or fever due to its high risk of bleeding.
    • NSAIDs (like ibuprofen and naproxen) and acetaminophen (Tylenol) are better for treating pain and fever thank Aspirin.
    • Aspirin raises your risk of bleeding, especially when used with other blood thinner medications like warfarin (Coumadin).
    • Studies show that using higher doses of Aspirin (162 mg or more) every day raises your risk of stomach bleeding and doesn't provide any additional heart protection.
    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.
    • Using low doses (81mg) of Aspirin every day can lower your risk of heart attack and stroke, but it isn't good for everyone. Only take Aspirin daily if your doctor recommends it.
    • Higher Aspirin doses can be used to treat occasional pain, swelling, and fever. Using ibuprofen or acetaminophen (Tylenol) instead can lower your risk of serious bleeding.
    • Take with food to lower the chance of an upset stomach.
    • Don't use for kids younger than 18 years old.
    • Stop taking this right away and tell your doctor if you have ringing in your ears, unusual bleeding, or nausea or vomiting that doesn't go away.
    Learn more
    More about CoumadinSide effectsReviews & ratingsAlternativesFDA package insert
    More about AspirinSide effectsReviews & ratingsAlternativesFDA package insert