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Taking a Blood Thinner? Here’s What You Need to Know

Debra Gordon

Last updated: October 20, 2016 7:33 pm

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Blood thinners, or anticoagulants, do just what their name implies: They keep your blood from clotting. Blood clots can cut off the blood supply to your heart, lungs, or brain, causing strokes, heart attacks, or respiratory failure. The most common reason they are prescribed, however, is for atrial fibrillation, an irregular heartbeat. The condition significantly increases your risk of stroke.

You may also be prescribed anticoagulants if you have:

• heart disease
• problems with blood circulation or blood flow
• atrial fibrillation (abnormal heartbeat)
• had heart valve surgery
• congenital heart defects

More than 2 million people in the United States take blood thinners – which are generally quite safe. The major risk is bleeding, particularly in the stomach or brain. That’s why it’s important to take only the dose your doctor recommends, and to follow any directions regarding other medications and certain foods.

Determining Your Risk for Blood Clots

The National Heart, Lung, and Blood Institute as well as the Centers for Disease Control and Prevention, and the U.S. Department of Health and Human Services (HHS) have identified the following among blood clot risk factors 1:

  • Being 65 years of age or older.
  • Taking hormones, especially for birth control.
  • Suffering prior serious health issues, including cancer, stroke, or heart trouble.
  • Getting a bad bump, bruise or significant broken bone.
  • Having varicose or bad veins.
  • Experiencing a prior blood clot.
  • Being a smoker.

You may also be at risk if you have any of the following conditions:

  • Obesity or overweight.
  • Pregnancy.
  • Dehydration.
  • Have a family history of blood clots.

Recognizing Blood Clot Symptoms

According to the HHS, you may have a blood clot if you are experiencing any of the following:

  • Swelling, soreness or pain in arms or legs.
  • Redness of skin.
  • Warmth in an area of the leg. 2

Blood clots in legs or arms may dislodge and travel through the body. If a blood clot has entered your lungs you may experience the following:

  • Breathing difficulties.
  • Pain in chest.
  • Fast heartbeat.
  • Fainting spells.
  • Slight fever.
  • Cough, with sputum that may contain blood. 3

Preventing Blood Clots

Whether your risk of a blood clot is high or not, it is best to try to prevent them, if possible. These tips from the HHS can help you prevent experiencing blood clots and their symptoms:

  • Wear clothes that are loose-fitting.
  • Raise your legs above your heart periodically.
  • Ask your doctor if you should wear compression stockings.
  • Exercise regularly.
  • Move around and change your position often.
  • Do not stand or sit for more than an hour.
  • Cut back on the salt you eat.
  • Avoid hurting your legs and try not to cross them.
  • Raise the bottom of your bed four to six inches. 4

There are several types of oral blood thinners available:

Aspirin. Just taking an aspirin every day (81 mg to 325 mg) can reduce the risk of blood clots (and protect you against heart attacks). Aspirin as blood thinners, however, are reserved for people with a pretty low risk of stroke.

Warfarin (Coumadin®). Warfarin was the first oral blood thinner. It’s been around for more than 50 years, which is why it’s considered the “gold standard” of stroke prevention. It’s not the easiest drug to take, however. There are certain foods and medications that can interact with warfarin, either making it less effective at preventing blood clots or increasing the risk of bleeding. You also need to have your blood levels monitored on a regular basis via a blood test.

Clopidogrel (Plavix®). This medication is mainly prescribed if you can’t take warfarin or one of the other medications listed below. It is usually taken with aspirin.

Dabigatran (Pradaxa), rivaroxaban (Xarelto®), and apixaban (Eliquis®). These are the newest anticoagulants available. According to their manufacturers, they’re intended to work just as well as warfarin with fewer drug interactions and no need to monitor your diet. You also don’t need blood tests to monitor drug levels. One downside is that they tend to cost more than warfarin. Besides the cost, additional issues with newer anticoagulants, like Pradaxa and Xarelto, exist. Pradaxa and Xarelto have been linked to increased risks of hemorrhaging and uncontrollable bleeding that has been cause for FDA intervention and multiple lawsuits.

Before filling any prescription for an anticoagulant, however, ask your doctor the following questions:

1. Why do I need an anticoagulant? Are there lifestyle changes I can make instead?
2. How long will I need to take it?
3. How will we know if it’s working?
4. What is the risk of bleeding?
5. Why are you prescribing this type of anticoagulant?
6. Are there any interactions with other medications?
7. Do I have to follow a special diet?
8. What side effects are possible?
9. How will I know if I have unexpected bleeding?
10. What if I need surgery?

Take your medicine as instructed. Some anticoagulant drugs require regular blood tests. It is important to control diet (e.g., vitamin K) and other factors (e.g., vitamins, herbal preparations, cold medicine, sleeping pills, antibiotics), as these can make anticoagulants stronger or weaker, which can be dangerous. And it’s critical to discuss management of anticoagulation during pregnancy with your cardiologist and obstetrician.

Can anticoagulants cause complications?

Yes. Sometimes the medication can cause bleeding problems, headaches, dizziness, pain, and discomfort. Call your doctor if you notice:

• bruises, blood blisters, purple toes
• swelling
• blood in your urine or stool
• stools that look like coffee grounds
• excess bleeding during your period
• pain, change in temperature

Popular Misconceptions about Anticoagulants

Here are some myths commonly associated with anticoagulants:

MYTH: Anticoagulants are called blood thinners because they thin the blood.
FACT: Anticoagulants do not thin the blood; they simply prevent it from forming clots. 5

MYTH: Anticoagulants break up clots.
FACT: Anticoagulants do not dissolve existing blood clots. “Clot-busting” drugs (thrombolytic agents such as tissue plasminogen activator or t-PA) can dissolve blood clots. 6

MYTH: Anticoagulants and antiplatelets are the same thing.
FACT: Both types of drugs keep a clot from forming or stop a clot from growing. Anticoagulant drugs work on chemical reactions in your body to lengthen the time it takes to form a blood clot. Antiplatelet drugs (e.g., clopidogrel) prevent platelets from clumping together to form a clot. 7

MYTH: Anticoagulants have been around since 1954, so they are safe.
FACT: A side effect of all anticoagulants is the risk of excessive bleeding. Symptoms of serious bleeding include: passing blood in your urine or stool, severe bruising, prolonged nosebleeds, coughing up or vomiting blood and increased bleeding during your period. 8

MYTH: If anticoagulants are advertised on TV, they must be safe.
FACT: Talk with your physician to weigh the benefits and risks of any medication, and ask about medication side effects. A 2014 study showed Pradaxa carries a higher risk of major bleeding and of gastrointestinal bleeding compared to the traditional blood thinner warfarin — and significantly greater than originally appeared to be the case at the time of FDA approval. 9  In 2014 the FDA required Xarelto to update its “black box” warning; there are certain risks and potentially dangerous side effects that accompany taking anticoagulants. 10

INTERESTING FACT: Anticoagulants occur naturally in blood-sucking insects like mosquitoes, fleas and ticks that bite to feed on blood. They inject a tiny bit of anticoagulant material at the site of the bite, to allow blood to flow without clotting during their brief meal. 11

INTERESTING FACT:  Leeches have an enzyme in their saliva called hirudin, a powerful anticoagulant. They produce this to prevent their host from forming a clot so that they can feast on blood more easily. 12

  1. http://www.ahrq.gov/patients-consumers/prevention/disease/bloodclots.html; https://www.nhlbi.nih.gov/health/health-topics/topics/pe/causes; http://www.cdc.gov/ncbddd/dvt/travel.html 

  2. http://www.ahrq.gov/patients-consumers/prevention/disease/bloodclots.html  

  3. http://www.ahrq.gov/patients-consumers/prevention/disease/bloodclots.html  

  4. http://www.ahrq.gov/patients-consumers/prevention/disease/bloodclots.html 

  5. http://www.medicinenet.com/script/main/art.asp?articlekey=2490

  6. http://www.heart.org/HEARTORG/Conditions/HeartAttack/PreventionTreatmentofHeartAttack/Cardiac-Medications_UCM_303937_Article.jsp#

  7. http://www.nlm.nih.gov/medlineplus/bloodthinners.html

  8. http://www.webmd.boots.com/stroke/tc/anticoagulant-medicines-side-effects

  9. http://www.ncbi.nlm.nih.gov/pubmed/25365537

  10. U.S. Food & Drug Administration. “Xarelto (Rivaroxaban) Tablets. Boxed warning.” (March 2014.) www.fda.gov. Accessed Oct. 27, 2014. 

  11. http://www.alternativz.co/knowledge-article/insect-bites-a-basic-overview/#.VJnx0Sc0

  12. https://wiki.uiowa.edu/display/protocols/Leech+Therapy+-+Anticoagulation+Protocols