Common Blood Thinners and Anticoagulant Drugs

By Stephen T. Sinatra, M.D., F.A.C.C., F.A.C.N., C.N.S., C.B.T.

If you’ve had a stroke or are at high risk for one, or have atrial fibrillation, or deep venous thrombosis, your doctor will likely prescribe you a blood thinner. Some of the most common blood thinners are warfarin (Coumadin), aspirin, and clopidogrel bisulfate (Plavix).

What Are Blood Thinners?

Blood thinners are most often prescribed for the prevention of stroke and clots. The drugs are also prescribed after a hip or knee replacement to prevent embolisms, as was the case after my hip was replaced.

Blood thinners are technically called “anticoagulants,” because they prevent or treat coagulation, the formation of clots. I think the nickname comes from “paint thinner.”

Although advertising influences which drugs patients request from their doctors (and doctors, sadly, all too often oblige), there is no simple, cookie-cutter approach. Anticoagulation therapy needs to be individualized.

How Blood Thinners Work

Common blood thinners work in one of two ways. Coumadin, which has been around for more than 60 years and is the oldest anticoagulant drug, works the first way: by neutralizing clotting factors in the blood. Coumadin decreases blood clot formation by reducing the body’s level of vitamin K1, which regulates clotting. It has shown unparalleled ability to thin the blood and prevent unwanted blood clotting.

Other blood thinners, like clopidogrel (Plavix), work by preventing blood platelets from clumping. Platelets are irregularly shaped cell fragments in the blood that can cause sticky blood and thus enhance clotting. In my own clinical experience with Plavix, I’ve seen very few adverse symptoms. It seems to be tolerated better than aspirin as an anticoagulant.

Is Aspirin a Blood Thinner?

Another type of blood thinner, aspirin is useful for individuals with arterial disease and those who have undergone stenting or bypass surgery. Like Plavix, aspirin works by preventing blood platelets from clumping together. In such cases, doctors often prescribe aspirin, sometimes as an accompaniment to a more potent anticoagulant.

Despite its potential benefits, the only time I condone regular aspirin use is when someone has documented coronary heart disease and can tolerate the drug. (I personally can’t tolerate it.) Should you have heart disease, I suggest a full aspirin every other day, to give your system a rest and still get the best effect.

Blood thinners are a double-edged sword. While the drugs help prevent heart disease and strokes, they also raise the risk of bleeding, even a stroke-induced hemorrhage.

For many years, doctors have routinely prescribed aspirin for primary heart attack and stroke prevention. But I’ve been cautioning patients and you, my readers, to think outside that box.

Aspirin is a major cause of GI bleeding and hospitalizations, and can trigger insomnia, rapid heartbeat, and liver damage. As I’ve reported previously, an authoritative publication for doctors and pharmacists unequivocally stated that the risks of long-term aspirin use should disqualify this practice from being considered for primary prevention.

Side Effects of Blood Thinners

The major side effect of blood thinners is excessive bleeding. For that reason, doctors require routine blood testing to monitor a measurement of coagulation called INR (International Normalized Ratio). Normal clotting ability on the INR scale is 1.0. For anyone with atrial fibrillation, the therapeutic INR target for effectively reducing risk for stroke is a reading of 2–3. An excess of any single anticoagulant, or of a combination of them, has the potential to raise your number and increase the risk of bleeding.

Coumadin is the most dangerous of the blood thinners for bleeding. However, aspirin can also cause bleeding, particularly in the gastrointestinal tract, and sometimes in other tissues. One of my patients on aspirin therapy had bleeding into his eye but could tolerate the aspirin well, without any GI distress whatsoever.

With Coumadin and/or aspirin therapy, I’ve had patients develop multiple ecchymoses, purple discolorations of the skin in various parts of the body. It’s caused by blood passing from ruptured blood vessels into tissue under the skin. This is not uncommon, especially if people suffer some minor trauma to their hands, arms, or legs.

Other possible side effects include nausea, vomiting, diarrhea, fever, bruising, anemia, blood in the urine, and rash. With Plavix in particular, side effects may include flu-like symptoms, headache, dizziness, pain, diarrhea, and upset stomach or indigestion.

Prescription Blood Thinners – Caution

Blood Thinner Medications & Nutritional Deficiencies

Blood thinners (except aspirin) can cause vitamin D and calcium deficiencies that can lead to softening, weakening, and thinning of bones. With elderly patients who suffer from atrial fibrillation and take Coumadin, one of my biggest fears has always been this: What if they were to fall and fracture a hip, or even worse, crack their heads and suffer a fatal subdural hematoma?

I’ve seen these things happen. In treating such cases, cardiologists are always engaged in a challenging and delicate balancing act. However, taking supplements to counteract the depletions can help to avert disaster.

I recommend patients on blood thinners take daily supplements of 2,000 IU of vitamin D, and calcium: 100 mg for men and 200 mg for women. Although green leafy vegetables, a rich source of vitamin K1, are usually restricted, I allow my patients to have a 4-ounce serving three or four times per week.

I also recommend shoring up one’s vitamin C status. Blood thinners can deplete this fundamental nutrient, which might contribute to spontaneous bruising, loose teeth, and swollen and bleeding gums. Aspirin alone can cause a deficiency of folic acid, vitamin C, iron, sodium, and zinc. Follow a foundation vitamin/mineral program containing vitamin C, folic acid, and zinc.

Who Should Take Blood Thinner Meds

If you have a prosthetic heart valve (metal or plastic), Coumadin is the only anticoagulant to take, and you must take it. No ifs, ands, or buts.

If you have atrial fibrillation, you need a blood thinner, and Coumadin is usually prescribed. If you don’t have an enlarged left atrium or significant mitral regurgitation, consult with your doctor about using a combination of aspirin and the nutritional supplement nattokinase (see Alternatives).

Who Should Not Take Blood Thinner Drugs

Anyone who has a stomach ulcer, hemophilia, or any other condition that may cause bleeding should not take blood thinners. Coumadin and Plavix should not be used by people who have high, uncontrolled blood pressure.

I wouldn’t give a prescription blood thinner to someone with atrial fibrillation who is over 90 and is unsteady on their feet, because their risk for falling injuries trumps stroke prevention. But if that same person has a mechanical (metallic or plastic) valve, Coumadin therapy is a must. Aspirin won’t cut it because it isn’t strong enough.

New Anticoagulants

Recently, the Food and Drug Administration approved a German blood thinner, Pradaxa (dabigatran etexilate). The first of a new generation of anticoagulants, it is designed to prevent stroke and blood clots in people who suffer from atrial fibrillation that is “non-valvular,” meaning not due to a heart-valve problem. In the United States, the drug maker estimates that about 95 percent of atrial fibrillation cases are non-valvular.

Previously, Pradaxa has been marketed in Europe. Only time will tell how much better the new anticoagulant works, compared to Coumadin. Some downsides of Pradaxa include bleeding in the elderly and renal impairment in younger people. More new anticoagulants have recently entered the market, including Xarelto (rivaroxaban), Eliquis (apixaban), and Savayasa (edoxaban).

Patients with stents, including drug-eluting (medicated or drug-coated) stents, need long-term anticoagulation therapy to prevent the danger of clotting at the stent site. Plavix is necessary for anyone with a drug-eluting stent.

Alternatives to Anticoagulants

In my practice, when elderly people need a blood thinner, I often put them on nattokinase (50 mg twice a day) and fish or squid oil (1–2 grams daily). But beware, never take nattokinase with Coumadin. Anyone taking Coumadin, Plavix, or aspirin can take the same dose of fish or squid oil but should be sure not to take more than 2 grams daily.

Is It Safe to Mix Fish Oil and Blood Thinners?

These are other suitable alternatives to try: garlic (1–2 grams daily) and ginger in the form of a daily tea. You can boil diced ginger, adjusting the strength to your taste, or buy ginger tea at a health food store. However, if you want to try any alternatives, you must always work with your doctor.

Earthing (grounding) is another great, natural method to prevent red blood cell clumping and improve zeta potential (a measure of blood stickiness). We know that anybody on a pharmaceutical blood thinner who is Earthing themselves must work closely with their doctor to monitor their INR level and avoid too much thinning of the blood.

This article originally appeared in the June 2011 issue of Dr. Sinatra’s monthly written newsletter, Heart, Health & Nutrition. HMDI has reprinted this article with permission from Healthy Directions, LLC, and since adapted it © 2011 Healthy Directions, LLC, 2016 Healthy Directions, LLC and HeartMD Institute. All rights reserved.

Leave a Reply


  1. john milat

    on August 23, 2014 at 8:03 pm

    can blood thinners cause bleeding in the intestinal track and difficult to locate does the drug effect the intestines that causes bleeding in more than one location does the drug injure the walls of the intestines making them fragile….your help will greatly appreciated,,thank you

  2. john milat

    on August 23, 2014 at 8:05 pm

    [quote]can blood thinners cause bleeding in the intestinal track and difficult to locate does the drug effect the intestines that causes bleeding in more than one location does the drug injure the walls of the intestines making them fragile….your help will greatly appreciated,,thank you[/quote]

  3. Kappa

    on September 29, 2014 at 5:54 pm


  4. Soli Diano

    on February 25, 2015 at 3:20 pm

    My mother is 89 years old. She has recently suffered a bronchial infection and has been on Avelox and a steroid pump.

    Her cardiologist has recently indicated that she has artrial fibrillation and took her off her low-dose aspirins and gave her Xarelto fearing she would have a stroke. My mother has an ulcer and she is seriously allergic to many medications including codeine. I am concerned as to why he prescribed her this medication which has many side effects including bleeding and the warnings that Xarelto should not be taken if she has an ulcer.

    My mother has not been taking any blood thinners other than aspirin and has been eating garlic every day. What would be the best blood thinner or treatment for her?

  5. Pamela Holtel

    on March 16, 2015 at 7:22 pm

    In 2007 I was taking Plaix and up with an
    Emergency colonosomy and had it reverse 3 months later. The doctors could not figure out the reason for itbut took me off blood thinners. I wonder if theycaused the bleeding in the first place so I would be wary if I was you

  6. Elizabeth Kenoyer

    on May 8, 2015 at 12:25 am

    I have prosthetic heart valves and take coumadin. Why can’t I take nattokinase and fish or squid oil instead of coumadin? WHy not?

    Thanks. Waiting for an answer please.

  7. Elizabeth Kenoyer

    on May 8, 2015 at 12:26 am

    I have prosthetic heart valves. Why cant I take nattokinase and fish or squid oil instead of coumadin? Please answer soon. Thank you.

    Elizabeth Kenoyer

  8. James Quinones

    on October 15, 2015 at 3:13 am

    # sandeep dey: Did you ever get an answer to above. I got a blister in my ankle and recently got a shot of Cortisone from a dermatologist. Almost two weeks and don’t see any change or improvement.

  9. Elaine

    on November 12, 2015 at 3:55 am

    I have had two heart attacks I am 64 I have a stent from my first one but nothing was blocked when I had the second.I do not know what to do i am hypersensitive to all sorts of meds but blood thinners make me so ill I cant take any I am asthmatic so asprin may be another problem.Please help I am losing my mind.

  10. Elaine

    on November 12, 2015 at 4:01 am

    Please help me after two heart attacks I am 64 first had a stent second no blockages.I am hypersenitive to meds blood thinners are one of the worst I feel like I am losing my mind have tried to take them but am so ill cannot get off the bed most days. I am asthmatic also asprin could be a problem.Any suggestions thank you .

  11. maremags

    on December 18, 2015 at 3:57 am

    What happened with your mom? My mom is 85 fell and fractured her femur. Healthy prior to the fall, she developed afib, was treated with xarelto, unknowingly had stomach ulcers which bled due to the blood thinners. She was taken off xarelto, then put back on it to only have additional bleeding. She was again hospitalized, given blood and taken off xarelto. She then suffered a stroke. Now she is hospitalized again, most recent diagnosis is doctors are stopping the blood thinner (this time heparin) because she had an active bleeding ulcer. She’s caught in a vicious cycle.

  12. gangadhar

    on December 23, 2015 at 11:27 am

    Hi Sir,
    I have blood thinner problem and also my BP level 180 to 240. how to reduce the blood thinner problem ? how to take precautions plz advice….

  13. Loretta Abbey

    on February 2, 2016 at 11:14 pm

    I am 73 last week had a Tia. was put on Clopidogrel 5mg tag. I take half a tab. only been on it 1 week and am now having blood in stool. would nattokinese 50 mg be a better choice with fish oil?
    I am really frightened to keep taking this, but do not want another Tia. My blood pressure is usually 120/65 or 70. I take no other drugs. ( I do take baby aspirin at bed time)

  14. Roy Hartsell

    on October 20, 2016 at 8:23 pm

    Have had by-pass and now on Plavix and aspirin. I scraped my thumb on the refrig-shelf- just very small scrap and it bleed for 45 minutes before I put direct pressure on it. It would still be bleeding. This is very scary and do not want to live at the e-room. Have history of nose bleeds. Am horrified .

  15. Dale

    on February 13, 2017 at 1:15 pm

    I am taking several prescription drugs for a TIA and for two stents installed about five years ago.
    I want to know if any of the following are considered blood thinners — Atorvastatin, Gabapentin, Isosorbide or Metoprolol .
    Thank you

  16. gary s.

    on March 6, 2017 at 3:05 pm

    October, 2015 at age 76 I had a pulmonary embolism with many blood clots on my lungs. for a long time, years, I probably took vitamin D3 1000 I.U. a day without taking K-2. under those conditions, how long would it take to create atherosclerosis build up and therefore have a plaque rupture causing the blood clots on my lungs? I now take xarelto and was told by the doctor I will need to take them until age 86 when the risk will be the same if I take xarelto or not.

  17. Edie P.

    on March 31, 2017 at 3:11 am

    After 2 or 3 weeks I got off Xarelto and Amiodorone 200/day because of tarry stool x2days and extreme fatigue, dizziness, and loss of balance. (I had normal blood count CBC-I am prone to bleeding from Aspirin) I had one episode atrial fib that lasted about an hour. Was given IV med in ER where I converted after 20 mins. Follow up Echo revealed normal ♡ & normal e f . 24°halter no atrial fib. Normal BP. Now I am herbal tea totaller + very strict healthy eating, extra clove of garlic am&pm. Fish oil 2.5gm/day +Tumeric with Bromelium 300mg +Culturelle probiotic. I am 80yo none smoker doing aquatics 30mins daily. Question is should I take Nattokinase? Should I add anything else? Thank you so much. Edie

  18. Antoinette Haliday

    on June 30, 2017 at 6:52 am

    I have to stop taking Pradaxa for 5 days before some minor surgery. Am I in danger and should I keep to a normal routine?

  19. J Collins

    on July 1, 2017 at 12:04 am

    My husband is almost 71 . Severe pain in. Left side, he starting seeing blood in his urine, & sometimes little pieces also.. No burning, had for a. Month, was prescribed anitinbotic to stop, still bleeding , went to get a cut & bladder test,, but he has been dizzy sometimes,& never had Bp problems, so he goes to urology to get test , does not do it, said he thought his heart was in a fib, so he contacts a cardiologist , they did a ekg, didn’t sound like much sends him home, they started scheduling him with bunches of test and a follow up appt after those test, ordered a heart monitor, then prescribes blood thinners,
    He is weak from a month of bleeding, dehydrated , fever every night. Re-.schedules him for his ct scan & bladder July 10 (holidays )’ so my question is should he be taking blood thinners , still bleeding,dehydrated , ? Shouldn’t they find out what the scan & bladder test say??

  20. HeartMD Editor

    on July 5, 2017 at 10:16 am

    Hi J Collins,

    I would recommend that you review your husband’s situation with one of the doctors on Dr. Sinatra’s Top Docs List. Dr. Sinatra cannot give direct medical advice and a situation such as this would need to be reviewed in careful detail. You can see the list here: Also note that many of the cardiologists on the list can do phone consultations as well, so be sure to contact those who are not local to you.

  21. HeartMD Editor

    on July 5, 2017 at 10:59 am

    Hi Antoinette,

    It is common practice to stop the use of blood thinners prior to surgery. Consult with your cardiologist to be sure there are no other precautions you should be taking during that time.

  22. Ruth K.

    on July 31, 2017 at 11:20 am

    I have recently had a blood test showing that my calcium in blood was low: 6.5. Previously, it had been high ranging about 11.2 for several years. The drop of about 5 points from high to low is of concern for my doctor. She is sending me for a parathyroid test for the second time. The first test several years ago showed the glands to be normal. I think that they still are. I believe that since I started taking Xalelto about 2 years ago, that may be the cause of the drop in calcium levels. I do not take vitamin D although I believe that I should be on it. The heart doctor put me on the blood thinner because I have severe atrial fib. My primary doctor ordered the
    parathyroid test again which I believe may be unnecessary. Lab tests revealed the high calcium in blood which they never could find a reason for the high number for many years. Thank you.

  23. Jeannie bailey

    on September 19, 2017 at 6:39 am

    Looks like no one answered these folks

  24. kate

    on November 19, 2017 at 12:22 am

    i think that’s why it’s called a comments section,not a question and answer forum.

  25. Ossama d.

    on March 19, 2018 at 4:25 am

    For how long should i take plavix after coronary stenting? And is there any side effects if using it for lifetime?

  26. HeartMD Editor

    on March 22, 2018 at 10:10 am

    Hi Ossama,
    The length of time one needs to stay on blood thinners after stenting is variable. The good news is, often they can be discontinued after a year. There are many blood thinners to choose from, discuss the different options and their side effects with your doctor to get more information.

  27. michaele a.

    on April 19, 2018 at 1:50 am

    I need to know where to have all fat-soluble supplements, including mk7, converted to water-soluble form, as I’ve had a full ileostomy. I want these supplements, after reading literature from Dr. Sinatra, for atherosclerosis and severe osteoporosis. Thank you from a big fan.

  28. Patricia M.

    on May 7, 2018 at 12:18 pm

    I’m 81 years old and have been on Plavix since 1992 and I can not take aspirin, so how long am I to take Plavix?

  29. Paul

    on October 2, 2018 at 11:04 am

    Very helpful. Thank you.

  30. Roccy D.

    on November 9, 2018 at 8:35 am

    I am a 78 year old male who suffered a bilateral embolism 3 years ago and put on 5 mg of Eliquis which was reduced to 2.5 after 6 months. I have been evaluated by Cleveland clinic Dr who specializes in anticoagulants and advised that since there was no lower leg clots they could not determine why I had the ambulism and thus I might have to stay on Eliquis. which I appear to tolerate very well. I do not take statins however, I have been advised to do so since my cholesterol is high and has been for years. I chose not to do so but decided to lose some weight and then redo the blood tests and see the results. I now weigh 164 lbs. down from 175 two months ago through walking and low carb diet.
    I don’t bleed a lot and would think I bleed more when on baby aspirin than this Eliquis. I also take enalapril 5 mg for hypertension although my bp seems to be good, i.e. 125/80

    Q 1 can I ever get off this drug and if so how, and how will monitor the slow trip down.?

    Q2 who should help me in this effort if I choose to try?

  31. Michael G.

    on December 19, 2018 at 10:44 am

    I am 66 years old and was diagnosed with end stage cirrhosis 7 years ago. I have had 2 DVT’s since. One mitigated with meds, the second required an emergency small bowel resection . I was prescribed warfarin but was switched Eliquis a while back. Now I have had the Eliquis stopped because of anemia until my doctors can decide on an alternative. This makes me very nervous. Is there a natural supplement that I can take while waiting on visit with hematologist? Will likely be a month before seeing hematologist because of holidays. Cirrhosis caused by hep-c from blood transfusion in mid 60 ‘s.

  32. Kathryn Bormann

    on February 23, 2019 at 1:36 am

    Have been on Xarelto for 7 days. 82 yrs old & was diagnosed with a Fib. Just went to ER because Im covered with hives. Taking Benadryl talking to Pharmacist tomorrow! About what other Blood Thinner I can be on! Do not want to take Coumadiin!!

  33. Maybritt U

    on December 30, 2019 at 12:57 pm

    I had previously had a blood clot in my leg – 6 months on Coumadin.
    Then – two years ago they discovered in the ER room CAT scan on my urinary track infection that I have a blood clot in my right lung. So BOOM now Xarelto for the rest of my life ! I do not like this, I take 20 mg a day. Could it be lower or could I stop sometime? I don’t like meds, but here I am stuck on this thing FOR THE REST OF MY LIFE ! I go in for tests once a year – lots of blood tests. I’m not a “go to the dr. person” nor a med person. I was also told not to take such and such vitamins, but I take Dr. Sinatra’s Gold pack every day anyway. Help, what is my next step??

  34. Lynda

    on March 11, 2020 at 5:51 am

    I have had 1 heart attacks I am 60 I have a stent from my first one but nothing was blocked when I had the second. I do not know what to do i am hypersensitive to all sorts of meds but blood thinners make me so ill I cant take any I am asthmatic so asprin may be another problem.

  35. HeartMD Editor

    on March 13, 2020 at 6:17 pm

    Hi Lynda, Try 1 to 2 Grams of omega-3 fish oil or Calamarine (squid) oil. I personally take the Omega 3 Calamarine oil you can find at or on Amazon. I personally visited the source plant in Norway and was highly impressed. Here is some info:

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