What is Blood Thinner?

Tricia Christensen
Tricia Christensen

A blood thinner, or anticoagulant, is a drug that is used to prevent blood clots from forming or to lengthen the time that it takes for blood clots to form. These drugs are often used by people who are at risk for heart attack, stroke or heart disease. There are many chemical formulations for blood thinners, and they can help prevent clotting in various ways. Those that block blood platelets from forming clots are called antiplatelet drugs. Others inhibit certain other clotting factors or the actions of a protein called thrombin, which plays a role in clotting.

Aspirin is one type of medication used to thin the blood and help prevent clot formation.
Aspirin is one type of medication used to thin the blood and help prevent clot formation.


The most common blood thinner is aspirin, an antiplatelet drug that has been recognized as a blood thinner since the middle of the 20th century. Often, a daily dose of aspirin is the only required cardiac medicine for people who are at risk for heart attack, stroke or heart disease. Patients who have certain medical conditions or are taking other medications should consult a healthcare professional before taking a daily dose of aspirin, because this medication could increase the risk of internal bleeding or other complications.

Fish oil may increase the risk of bleeding problems for someone who is already taking aspirin.
Fish oil may increase the risk of bleeding problems for someone who is already taking aspirin.

Conditions that might contribute to those risks include stomach ulcers, congenital blood disorders and asthma. Medications that might interact with aspirin include ibuprofin, heparin, warfarin and some antidepressants. Certain dietary supplements, such as ginkgo and fish oil, also might increase the risk of bleeding problems for someone who is taking aspirin.

Routine blood tests may be required to determine the proper dose of blood thinners.
Routine blood tests may be required to determine the proper dose of blood thinners.

Children who were born with congenital heart defects and who have undergone surgery often are prescribed a daily dose of aspirin, which helps prevent platelets from clumping together and forming clots. The use of aspirin by children must be carefully monitored and should be stopped if the child has a stomach flu, influenza or chicken pox. This is because the use of aspirin by children has been indicated in the development of Reye's syndrome, an illness that can cause damage to the major organs of the body and might be fatal.


In some cases, aspirin is not a strong enough blood thinner to address the risk of potentially life-threatening clots forming. The second most common blood thinner is warfarin. It is much stronger than aspirin, so its use must be carefully monitored. Dosing is difficult because warfarin is highly reactive. Determining the proper dosage can take several months of making adjustments and might require weekly blood tests before an ideal dose is achieved.

Patients who take warfarin and other anticoagulants are advised to monitor their intake of foods that are high in vitamin K, which can reduce the effectiveness of the drug. They also are cautioned about the risks regarding severe bleeding after bruising or cutting the skin. There is a risk of cranial bleeding if the patient incurs a head injury. Children who take warfarin are often cautioned to wear helmets when engaging in any kind of rough play.


One of the more recently developed blood thinners is clopidogrel, an antiplatelet drug. Clopidogrel is more stable than warfarin and has fewer side effects, but serious side effects — such as slurred speech, seizures, bloody vomit and severe headaches — are still possible and should be reported to a healthcare professional as soon as possible. Some patients do not metabolize clopidogrel effectively, leaving them at risk for clots.


Another type of blood thinner, heparin, is injected directly into the blood stream and inhibits the actions of thrombin. It is often used during certain types of surgery, blood transfusions and dialysis, and it might be used to help keep intravenous (IV) lines from clotting. Heparin also can slow the growth of blood clots, although — like all blood thinners — it does not dissolve clots after they have formed.


If a patient is taking any of these drugs regularly, his or her physician should be notified. Many blood thinners can interact with other drugs and reduce the effectiveness of the blood thinner or increase the risk of complications. Among the many substances that might interact with blood thinners are ibuprofen, acetaminophen and even some herbal supplements, such as ginkgo or St. John's wort. Using more than one type of blood thinner also might increase the patient's risks, although a combination might also be prescribed in certain instances.

Additionally, patients should receive directions regarding stopping the use of blood thinners before any type of surgical procedure. Physicians and dentists usually recommend stopping about a week before surgery. Stopping the use of blood thinners is indicated only if doing so does not increase the risk of heart attack or stroke, however, and it should be done only under the direction of a healthcare professional.

Blood thinners may be used during certain types of blood tranfusions.
Blood thinners may be used during certain types of blood tranfusions.
Tricia Christensen
Tricia Christensen

Tricia has a Literature degree from Sonoma State University and has been a frequent wiseGEEK contributor for many years. She is especially passionate about reading and writing, although her other interests include medicine, art, film, history, politics, ethics, and religion. Tricia lives in Northern California and is currently working on her first novel.

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Discussion Comments


Is there any problem if I use warfarin and clopidgrel simultaneously?


A blood "thinner" is an agent that reduces the blood's viscosity. Examples of true blood "thinners" include aspirin and garlic. But the vast majority of the drugs being discussed in this article are not blood thinners. They are anticoagulants which reduce the blood's ability to clot. The two are not the same thing and are they interchangeable, neither in treatment nor in definition.

Why this insistence on describing anticoagulants as blood "thinners" is so widespread is totally beyond me!


@anon202241: You should always consult your doctor about a missed dose for this kind of medication. You need to call him and tell him you need instructions on what to do if this ever happens again. If it were something like an antibiotic, I'd say go ahead and take it and don't worry about it. With a blood thinner, I'd be more likely to say just take the next dose at the scheduled time, but I'm not a doctor. Please give your doc a call and ask what to do if this happens again.


If you are taking blood thinner every day at six p.m., and one day you forgot to take it, should you take it immediately when you remember? My guy was supposed to have it at six p.m., last night. I just woke up, realizing he had not had it and I am so concerned about what I should do. Should I go wake him and give him the shot, or wait until morning, or wait until the regular time of six pm. Right now it is almost 3 a.m. Anyone?


Can anyone give us advice? My 24 year old daughter began suffering from seizures and a dvt in her left arm in september. She's been on warfarin ever since and it has not had any effect. In fact, the clot has moved towards her chest. Please help!


Yes, the drug is called Pradaxa. I am currently prescribed it. It is true that is does not have a lot of the side effects that Plavix and Coumadin have, and I do not have to get my blood tested every week (like you would taking Coumadin).


sounds like aggrenox. i think its asprin and plavix, to answer anon64057.


I was on warfarin for hip replacement surgery. I no longer take it and need to know when I can start back to taking my baby aspirins each day. also should I have another blood test to make sure my count is back to normal? Thanks!


I was wondering if someone could tell me about how long it takes when you start coumadin to get your blood levels right. I am having an ablation on my heart and I need to be between 2.5 and 3.5.


once you are on a blood thinner, do you have to take it for the rest of your life? I don't like to be on any medication for long term, so how do they determine when you don't need it on a regular basis?


I had three blood clots in my arm, spent four days in icu, came home yesterday feeling much better. I am in no pain, but my arms are black and blue, spreading bruises. Does any one know why the bruising is getting worse?


to # 24: Aggrenox is the new drug.


My mother was on Plavix for years and recently broke her femur. I believe the doctors should have waited at least seven days for surgery due to the Plavix in her system. They operated after five days and she arrested and fell into a coma with severe brain damage. She died 18 days later, after life support was ceased.


my mother is 83 with a heart valve and is taking coumadin. Three a day for the last 10 years at least. she went to her Dr. yesterday and he told her that her blood was too thin so no coumadin on monday through thurs. she is to take three then on fri. and sun. take four. on sat. just take 3. My question is if her blood is too thin, why would they up the dosage, or is this OK?


How does Warfarin interact with the herb Lions Mane?

Are they compatible?


The new blood thinner is Effient,


Ive had a few strokes at the age 36. I'm on coumadin and lovanox. My levels are still .9-1.0 I am also on a aspirin 81mg. Why is it not working? I'm getting kind of scared.


The new blood thinner on the market is Effient; developed and tested in Europe; recently approved by the FDA for use in the USA.

Its benefits are that it can be taken by folks who take meds like Nexium or Protonix without losing effectiveness as Plavix does and there seem to be a lot less drug interaction problems. It's easy to take and does not require the constant blood monitoring that Coumadin does.


My husband recently had a heart attack and he was prescribed "Effient" the new blood thinner.


my 79 year old husband who has been on Plavix for some time is hospitalized now from a stroke in the back of his brain. He can walk and talk fine but is very confused and cannot read a word. They have him on a new oral blood thinner that I would like to find out something about but no one at the hospital has time to talk.

The nurse said it was something like oughgonaut, maybe argonot. Does anyone know a blood thinner with a similar name?


I am on a blood thinner for the last 10 years, and have been noticing that I am cold all the time, and I know it is only me who feels chilled.


how high is too high? my dad was at 8.9. two days later he hit 14-plus.


my husband was hospitalized for atrial flutter and he takes blood thinner. what is the average time someone would need to take blood thinner and is there a natural way to treat this?


how can you stop the bleeding in the mouth(bitten gum) of a person on blood thinner medication?


I'm taking Worf 10mg and 7 mg Olternet each day, but my blood ring is still 1.6. I'm worried about this.


Hi, I was wondering what blood thinners may be appropriate for a person of age 86?


I was hospitalized for a mild heart attack and was told that I need to have a blood thinner. I am taking plavix now. (clopidogrel)..Do I need it to take it in long term and why is it that I still have pain in my heart even when I was in the hospital? I stopped taking the crestor since i read that cholesterol medicine won't help and is risky anyway. I also stopped taking the losartan

Is it not a good idea to do this?


My grandpa is 80yrs old. He had a mild attack. Doctor has prescribed him to take ecosprin-150mg at nights alone, but my grandma gave him 2 ecosprin this morning by mistake. Since the morning he is sleeping and very tired. Will this produce any side effects?


everyday i give blood thinner to my father but one day i forgot to give him the blood thinner. my question is if i missed 1 day of taking blood thinner what will be the result? thank you


i just found out i have a blood clot in my arm and now i am on blood thinners. I was wondering if drinking alcohol will affect it? long term? short term? if the alcohol will stay in my system or anything.


My son in 13 months old. He has to take a 1/2 a baby aspirin a day - 40mg. He had a stroke and to prevent more from happening he is required to take aspirin. Now I am scared of Reye's Syndrome. Are there any other blood thinners that are recommended for a child his age?


There is a new product on the market named KytoStat. KytoStat is as easy to use as a regular bandaid. Just apply it to the wound and it stops the bleeding. You don’t even need to wipe the blood away. In fact, the blood allows the chitosan in KytoStat to seal the wound. This bandage is very useful to individuals taking blood thinners.


How to remove RTV Silicone after it is set up?


For a short time I was taking aspirin, daily, 81mg, since it's values are so lauded, however, after a while I noticed I was bruising so easily. I would get blue marks all over my arms, that I had no idea how they got there.

Initially I did not know why, but eventually I came to realize that it was aspirin, which acts as blood thinner, that caused my bruises.

I stopped taking aspirin, at the recommendation of my doctor, and my bruises are gone too. Now, for most people aspirin is beneficial, but for some of us it is better not to take it daily. So, yes, blood thinners do cause bruises.


I am taking warfarin and am extremely overweight. Is there any kind of rule of thumb for dieting when on a blood thinner? I am afraid to change my diet now that my levels are pretty stable.


I recently read that in the first three months after stopping Plavix there is a large increase in the possibility of a heart attack. Is there a way to stop Plavix slowly?


Can having thin blood cause a large amount of bruises on your body??? Or can blood thinners cause bruises????

thank you,



Can blood thinner medications cause problems with cataracts?


Could you please let me know the name of the new blood thinner besides Plavix and Coumadin, and what the side effects to it there are.


I have heard there is a new blood thinner on the market now besides Plavix and Coumadin. It just came out recently and is experimental. It is suppose to be just as effective as Plavix but without all the side effects. Is this true and if so what is the name of this new drug and do you have any info on it?

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