- Atrial Fibrillation Slideshow: Causes, Tests and Treatment
- Atrial Fibrillation (A-Fib) Quiz: Test Your Medical IQ
- A Visual Guide to Heart Disease
- What are anticoagulants?
- Why are they used?
- List of anticoagulant side effects
- Drugs and herbal supplements that interact with anticoagulants
- Are anticoagulants, aspirin, and antiplatelets the same type of drug?
- Who shouldn't take anticoagulants?
- Different types or classes of anticoagulants
- List of brand and generic names, and preparations (oral, injection, tablet, pill, powder)
- Is it safe to take an anticoagulant if I'm pregnant or breastfeeding?
- Anticoagulant mechanism of action (how they work)
- Storage, preparations, and forms available in the US
What are anticoagulants?
An anticoagulant is a drug (blood thinner) that treats, prevents, and reduces the risk of blood clots-breaking off and traveling to vital organs of the body, which can lead to life threatening situations. They work by preventing blood from coagulating to form a clot in the vital organs such as the heart, lungs, and brain.
For example, a DVT or deep vein thrombosis (blood clot in the leg or lower extremity) can happen if you have a medical condition that keeps you immobile or if you have been sitting for n long period of time without getting up and stretching, like traveling by plane, car, or train. If the clot breaks off from the vein or artery of a leg it can get lodged in the blood vessels of the lung where it can form a clot in the lung (pulmonary embolism). This is a life threatening medical condition. Similarly, a stroke can be caused by a clot lodged in a vessel in the brain.
Anticoagulant treatment is used to prevent the formation of new blood clots, and to treat existing clots by preventing them from growing larger in size. It also reduces the risk of embolization of blood clots to other vital organs such as the lungs and brain.
Why are they used?
An anticoagulant medicine is used in patients to prevent blood clots from forming in veins, arteries, the heart, and the brain of a patient. For example, if the clot travels to the patient's heart it can cause a heart attack or if one forms in the brain it may cause a stroke or TIA (mini-stroke, transient ischemic attack).
Examples of diseases and health conditions that require treatment with anticoagulants to reduce the risk of clots forming, or are used to prevent life-threatening problems include:
Quick GuideAtrial Fibrillation: Heart Symptoms, Diagnosis, & Afib Treatment
List of anticoagulant side effects
The most common side effect of treatment with anticoagulant medicine is bleeding. Treatment with these products may cause various degrees of bleeding, including fatal bleeds.
This list of adverse effects associated with anticoagulants are compiled from adverse effects listed for various anticoagulants and may not apply to every medicine.
Common side effects include:
- Abdominal pain
- Flatulence (intestinal gas)
- Local injection site reactions
- Bruises caused by trauma (ecchymosis)
Other side effects include:
- Hair loss (alopecia)
- Itching (pruritus)
- Changes is sense of taste
- Fainting (syncope)
- Shortness of breath
- Low blood pressure (hypotension)
- Chest pain
Serious side effects include:
- Cholesterol embolus syndrome
- Intraocular hemorrhage
- Groin hemorrhage
- Tissue necrosis
- Respiratory tract bleeding
- Hypersensitivity reaction
- Hemorrhagic stroke
- "Purple toe" syndrome
- Increased fracture risk with long-term usage
- Elevation of serum aminotransferases
Drugs and herbal supplements that interact with anticoagulants
Treatment with more than one blood thinner or using medicine that can cause bleeding will increase the risk of bleeding from any anticoagulant. Examples of drugs that also can cause bleeding when they interact include:
- Antiplatelet medicine such as aspirin and other nonsteroidal anti-inflammatory medications (for example, ibuprofen [Motrin], naproxen [Aleve]), clopidogrel (Plavix), and prasugrel (Effient)
- Serotonin reuptake inhibitors (SSRIs) such as fluoxetine (Prozac) and paroxetine (Paxil).
- Garlic and ginkgo also increase the risk of bleeding when combined with another medicine that thins the blood because these herbs can cause bleeding when taken alone.
- Drug and herbal supplement interactions with warfarin
- amiodarone (Cordarone)
- trimethoprim/sulfamethoxazole (Bactrim)
- fluconazole (Diflucan)
- itraconazole (Sporanox)
- metronidazole miconazole
- voriconazole (Vfend)
- zafirlukast (Accolate)
- ciprofloxacin (Cipro)
- atorvastatin (Lipitor)
- clarithromycin (Biaxin)
- fluoxetine (Prozac)
- indinavir (Crixivan)
- ritonavir (Norvir)
Some drugs and herbal products that may reduce the anticoagulating effect of warfarin by increasing its breakdown include:
- St. John's wort
- carbamazepine (Tegretol, Tegretol XR, Equetro, Carbatrol)
- rifampin, bosentan (Tracleer)
Use of Warfarin with foods high in Vitamin K
Foods with high vitamin K content (for example, green leafy vegetables) reduce the anticoagulant effect of warfarin. It's important for patients to try to consume a consistent amount of vitamin K containing foods to avoid fluctuations in the effect of warfarin. A patient that regularly consumes high vitamin K containing foods may require a higher dose of Jantoven or Coumadin to achieve the desired level of anticoagulation.
Are anticoagulants, aspirin, and antiplatelets the same type of drug?
No. Anticoagulants and antiplatelets differ in how they work. Anticoagulants prevent blood coagulation by reducing the action of clotting factors directly or indirectly. Antiplatelets work by inhibiting the ability of platelets to participate in the clotting process. Aspirin is an example of an antiplatelet medication.
Who shouldn't take anticoagulants?
Anticoagulation therapy is not recommended for patients with certain diseases or health conditions because they increase the risk of bleeding. Patients who have any of the following health problems or are pregnant shouldn't use this type of therapy.
Different types or classes of anticoagulants
There are different types of anticoagulants, and they are classified by how they affect the normal coagulation pathway (see the mechanism of action section). The different classes are:
- Vitamin K antagonists (coumarin anticoagulants)
- Low molecular weight heparins (LMWH)
- Direct thrombin inhibitors
- Factor Xa Inhibitors
List of brand and generic names, and preparations (oral, injection, tablet, pill, powder)
Vitamin K antagonists
- warfarin (Coumadin, Jantoven) – oral tablets
Low molecular weight heparins (LMWH) and heparin (vials and syringes)
- bivalirudin (Angiomax) – powder for injection
- argatroban (Acova) - injection
- dabigatran (Pradaxa) – oral capsule
- antithrombin III (Thrombate III) – powder for injection
Factor Xa Inhibitors (These are relatively new anticoagulants)
Is it safe to take an anticoagulant if I'm pregnant or breastfeeding?
Most anticoagulants have not been adequately studied in patients who are pregnant because clinical trials exclude them. Therefore, this type of therapy generally is avoided during pregnancy and should be used during pregnancy only if the potential health benefit justifies the potential dangers to the fetus.
Warfarin, specifically, is a medication that should be avoided if you are pregnant or are planning to become pregnant. Birth defects and fetal bleeding have been reported during this type of therapy when taken during pregnancy. Be careful to not get pregnant if you are currently on this type of therapy. If you do become pregnant or are trying to conceive contact your doctor immediately.
Enoxaparin is an anticoagulant medicine that does not cross the placenta and shows no evidence of effects on the fetus. It is often recommended by doctors for patients who are pregnant as an alternative to oral therapy with warfarin, which cannot be safely used during pregnancy.
There is little data about the excretion of this medicine in breast milk. Available evidence suggests that warfarin is not secreted in breast milk. Since most medicines are excreted in breast milk, medical experts generally recommended that if you are receiving this type of therapy you should not breastfeed.
Anticoagulant mechanism of action (how they work)
How vitamin K antagonists (warfarin) cause anticoagulation
Warfarin prevents the formation of a blood clots in patients by reducing the production of factors II, VII, IX, and X, and the anticoagulant proteins C and S by the liver. These factors are involved in the body's natural clotting process. The production of these factors by the liver are dependent on adequate amounts of vitamin K. Warfarin reduces the production of the factors because it antagonizes vitamin K. The dose of warfarin is carefully adjusted to achieve optimal anticoagulation while minimizing the risk of bleeding.
How low molecular weight heparins (LMWH) and heparin cause anticoagulation
Heparin and low molecular weight heparins prevent a blood clot from forming by blocking the action of two of the 12 clot-promoting proteins in the blood (factors X and II) whose action is necessary for blood to clot. Low molecular weight heparins are produced by chemically breaking heparin into smaller-sized molecules. Unlike heparin, medical professionals do not monitor the effect of low molecular weight heparins with blood tests and the dose of a low molecular weight heparin is not titrated.
How thrombin inhibitors cause anticoagulation
Thrombin inhibitors work by blocking the action of thrombin, a protein that is necessary for the coagulation of blood and formation of a blood clot. Reducing the action of thrombin reduces the ability of blood to clot.
How factor Xa inhibitors cause anticoagulation
Factor Xa inhibitors are novel anticoagulants. They block the action of factor Xa which is an important protein in the coagulation cascade that causes blood to clot. Reducing the action of factor Xa reduces the ability of blood to clot.
Quick GuideAtrial Fibrillation: Heart Symptoms, Diagnosis, & Afib Treatment
Storage, preparations, and forms available in the US
Drugs in this class are available as tablets, capsules, powder for injection, prefilled syringes, and in vials containing a solution for injection. Some intravenous anticoagulants (for example, bivalirudin, and heparin) are administered via an intravenous infusion while receiving medical care in the hospital.
Oral anticoagulants are stored at room temperature. Prefilled syringes and multiple dose vials of low molecular weight heparins, and heparin vials are also stored at room temperature.
- Deep vein thrombosis (DVT)
- Blood clot in the lung (pulmonary embolism)
- Blood clots during AFib
- Heart attack
Common side effects of anticoagulants include:
- Flatulence (intestinal gas)
- Local injection site reactions
- Bruises caused by trauma (ecchymosis)
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Treatment & Diagnosis
Medications & Supplements
- apixaban (Eliquis)
- Ibuprofen and Plavix (Side Effects and Interactions)
- Lovenox (enoxaparin)
- dalteparin (Injection; Fragmin)
- Coumadin vs. Plavix (Differences and Similarities)
- rivaroxaban (Xarelto)
- fondaparinux - injection, Arixtra
- heparin lock flush-injection, Hep-Lock
- dalteparin vial - injection, Fragmin
Prevention & Wellness
Quick GuideAtrial Fibrillation: Heart Symptoms, Diagnosis, & Afib Treatment
Daily Health News
Subscribe to MedicineNet's Heart Health Newsletter
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
FDA Prescribing Information
American Heart Association. 2015. "What Are Anticoagulants and Antiplatelet Agents?"
Top Anticoagulants drug class of blood thinners Related Articles
11 Signs and Symptoms of Stroke
Stroke is a serious medical condition. If you think you or someone you know is having a stroke call 911 immediately.
There are two main types of strokes, hemorrhagic and ischemic (the most common type).
A hemorrhagic stroke occurs due to a blood vessel rupture in the brain. An ischemic stroke occurs when a blood clot becomes lodged in a blood vessel in the brain, which causes a loss of blood supply to the brain, possibly causing brain tissue death.
FAST is an acronym that helps people identify stroke signs and symptoms so they can act fast and call 911. Face drooping, Arm weakness, and Speech difficulty are indicators that a person may be having a stroke and it is Time to seek emergency medical treatment. Additional signs and symptoms of stroke may include weakness, difficulty walking, blurred vision, dizziness, headache, confusion, difficulty speaking, and loss of sensation. .
Stroke is a major cause of death and disability in the US. Early identification and treatment of stroke helps reduce the risk of morbidity and mortality.
Arrhythmia (Irregular Heartbeat)An arrhythmia is an abnormal heart rhythm. With an arrhythmia, the heartbeats may be irregular or too slow (bradycardia), to rapid (tachycardia), or too early. When a single heartbeat occurs earlier than normal, it is called a prmature contraction.
Atrial Fibrillation QuizLearn the causes, symptoms, and treatments of the common heart abnormality known as atrial fibrillation (A-fib).
A-Fib SlideshowAtrial fibrillation is the most common type of abnormal heart rhythm. Atrial fibrillation or AF can lead to serious heart complications like stroke. Risks associated with AFib are related to heart rhythm changes. Treating atrial fibrillation addresses these changes in heartbeat.
Blood clots can occur in the venous and arterial vascular system. Blood clots can form in the heart, legs, arteries, veins, bladder, urinary tract and uterus. Risk factors for causes of blood clots include
- high blood pressure and cholesterol,
- smoking, and
- family history.
Symptoms of a blood clot depend on the location of the clot. Some blood clots are a medical emergency. Blood clots are treated depending upon the cause of the clot. Blood clots can be prevented by lowering the risk factors for developing blood clots.
Deep Vein Thrombosis
Deep vein thrombosis (DVT) is a blood clot in the deep veins, and can be caused by broken bones, trauma to a limb, immobility, medications, smoking, cancer, genetic predisposition, and cancer. Symptoms of a deep vein thrombosis in a leg are
- warmth, and
Treatment for DVT include medications and surgery.
Heart AttackHeart attack happens when a blood clot completely obstructs a coronary artery supplying blood to the heart muscle. A heart attack can cause chest pain, heart failure, and electrical instability of the heart.
Heart Detail PictureThe heart is composed of specialized cardiac muscle, and it is four-chambered, with a right atrium and ventricle, and an anatomically separate left atrium and ventricle. See a picture of Heart Detail and learn more about the health topic.
Heart Disease (Coronary Artery Disease)
Heart disease (coronary artery disease) occurs when plaque builds up in the coronary arteries, the vessels that supply blood to the heart. Heart disease can lead to heart attack. Risk factors for heart disease include:
- High blood pressure
- High cholesterol
- Family history
Angina, shortness of breath, and sweating are just a few symptoms that may indicate a heart attack. Treatment of heart disease involves control of heart disease risk factors through lifestyle changes, medications, and/or stenting or bypass surgery. Heart disease can be prevented by controlling heart disease risk factors.
CAD SlideshowWhat is heart disease (coronary artery disease)? Learn about the causes of heart disease. Symptoms of heart disease include chest pain and shortness of breath. Explore heart disease diagnosis, treatment, and prevention.
Heart Disease SlideshowLearn about heart disease and heart attack symptoms and signs of a heart attack in men and women. Read about heart disease diagnostic tests, treatments, and prevention strategies.
Heart Disease QuizTake our Heart Disease Quiz to get answers and facts about high cholesterol, atherosclerosis prevention, and the causes, symptoms, treatments, testing, and procedures for medically broken hearts.
Heart: How the Heart WorksThe heart is a very important organ in the body. It is responsible for continuously pumping oxygen and nutrient-rich blood throughout your body to sustain life. It is a fist-sized muscle that beats (expands and contracts) 100,000 times per day, pumping a total of five or six quarts of blood each minute, or about 2,000 gallons per day.
Peripheral Vascular Disease
Peripheral vascular disease (PVD) refers to diseases of the blood vessels (arteries and veins) located outside the heart and brain. While there are many causes of peripheral vascular disease, doctors commonly use the term peripheral vascular disease to refer to peripheral artery disease (peripheral arterial disease, PAD), a condition that develops when the arteries that supply blood to the internal organs, arms, and legs become completely or partially blocked as a result of atherosclerosis. Peripheral artery disease symptoms include intermittent leg pain while walking, leg pain at rest, numbness in the legs or feet, and poor wound healing in the legs or feet.
Treatment for peripheral artery disease include lifestyle measures, medication, angioplasty, and surgery.
Pulmonary EmbolismA pulmonary embolism (PE) occurs when a piece of a blood clot from deep vein thrombosis (DVT) breaks off and travels to an artery in the lung where it blocks the artery and damages the lung. The most common symptoms of a pulmonary embolism are shortness of breath, chest pain, and a rapid heart rate. Causes of pulmonary embolism include prolonged immobilization, certain medications, smoking, cancer, pregnancy, and surgery. Promt medical attention should be sought if you think you or someome you know has a pulmonary embolus.
Stroke SlideshowWhat is a stroke? Learn about stroke symptoms like sudden numbness or weakness, confusion, vision problems, or problems with coordination. Discover causes and recovery of a stroke.
Take the Stroke QuizTake the Stroke Quiz to learn about stroke risks, causes, treatment, and most importantly, prevention.
Stroke Symptoms and Treatment
A stroke is an interruption of the blood supply to part of the brain caused by either a blood clot (ischemic) or bleeding (hemorrhagic). Symptoms of a stroke may include
- double vision or vision loss,
- vertigo, and
- difficulty speaking or understanding speech.
A physical exam, imaging tests, neurological exam, and blood tests may be used to diagnose a stroke. Treatment may include administration of clot-busting drugs, supportive care, and in some instances, neurosurgery. The risk of stroke can be reduced by controlling high blood pressure, high cholesterol, diabetes, and stopping smoking.