Anticlotting Drugs: What You Need to Know

Jeff Prescott and Yunlu Chen

What are anticlotting agents? They're medications that are used to prevent clots from forming in the blood or to shrink clots that have already formed. You may have heard these medications referred to as "blood thinners." There are different types - antiplatelets and anticoagulants - and the reason why a person may have to take them depends on the doctor's diagnosis.

Anticlotting drugs are very important, even though taking them may not make you feel any different. Severe consequences could occur if treatment is not taken seriously. For many people, adding this drug regimen - and sticking to it - is lifesaving.

Blood Clot Basics

There are many proteins, chemicals and clotting factors in blood that are normally in balance, allowing your blood to flow properly and nourish your cells. Some help the blood clot when you get an injury, and others break the clots down when you're healing. This is normal. Problems arise when clots form and fail to dissolve.

Clots in the veins can occur when there is low blood flow, along with too much clotting factor in the blood. Clots in the arteries happen due to artery plaque buildup and cardiovascular disease. These situations can become damaging and even life threatening, especially when the clots block blood circulation from the legs or major organs such as the brain, the heart or the lungs. Dangerous clots can occur without warning.

In the brain, a clot is known as a stroke, and in the heart, it is called a myocardial infarction or heart attack. You may be at higher risk for a heart attack or stroke if you:

-- Are older or are a man.

-- Have a family history or previous history of heart attack or stroke.

-- Have certain conditions, such as diabetes, irregular heartbeats, high blood pressure, high cholesterol or plaque in your arteries.

-- Are obese.

-- Use alcohol or tobacco.

-- Are sedentary (do not exercise).

In the lungs, a clot is called a pulmonary embolism (or PE), and in the legs, it is known as a deep vein thrombosis (or DVT). The risk for these conditions doubles every decade past 50 years of age. You may also be at higher risk for a PE or DVT if you:

-- Have a history of a PE or DVT.

-- Have hip or knee replacement surgery.

-- Are pregnant or take drugs containing estrogen.

-- Use tobacco.

-- Have a severe illness or cancer or are bedridden or paralyzed.

To prevent these events from happening, your doctor will prescribe you medications that he or she thinks will be the safest and most effective for you. Remember that medication alone is not the only answer to improving your health. It is very important for you to have a healthy lifestyle with proper nutrition and exercise.

Anticlotting Drugs

Anticoagulants such as warfarin, heparins, fondaparinux or dabigatran work by blocking vitamin K or inactivating other clotting factors in the blood. Antiplatelets such as aspirin, dipyridamole, ticlopidine and clopidogrel prevent clotting by blocking thromboxane, a chemical that rounds up clotting cells in the blood.

These medications all require careful management because they "thin out" your blood and can make you bleed more easily. Avoiding situations where you may fall or become injured is crucial to preventing these serious bleeding events.

10 Tips for Warfarin

-- Check your international normalized ratio (also known as INR) as scheduled.

-- Avoid missed doses, but do not double up on doses if you skipped.

-- Keep the amount of leafy green vegetables constant from day to day. Vitamin K is found in many vegetables and is a target warfarin works on to prevent clots. Eating too much or too little can affect your INR.

-- Consult your doctor before making changes to your diet, vitamins or OTC medications, because warfarin interacts with many things.

-- Avoid alcohol.

-- Take medication with a full glass of water at the same time every day, with or without food.

-- Make sure your doctor knows before you have any dental work or surgeries.

-- Carry an ID card that says you take warfarin in case of emergency.

-- Store your medication away from moisture, heat or light.

-- Tell your doctor if you are planning to get pregnant. Warfarin is not safe during pregnancy.

What Should I Watch Out For?

If you notice unusual bleeding, such as blood in your urine or stool; if you're coughing up or vomiting blood; or if you have unexplained severe bruising, skin color changes, headache, dizziness, reoccurring nosebleeds, or heavier than normal menstrual bleeding, seek medical attention. There are specific instructions on how you can manage each medication, so talk to your doctor or pharmacist for more details.

Note: This article was originally published on Dec. 14, 2012 on It has been edited and republished by U.S. News.