About Blood Clots and How to Treat Them

This information describes what a blood clot is and how it is treated.

About Blood Clots

When you have a cut or an injury, your blood clots to stop the bleeding. However, your blood can also clot without having an injury.

People with cancer have a higher risk of developing blood clots. This may be because some of the changes in your genes that cause cancer can also make your blood more likely to clot. Also, some of the chemotherapy medication that you get can increase your risk of blood clots.

Some people have certain conditions that make their blood more likely to clot during treatment for cancer. These conditions include inherited (passed down in families) disorders such as the Factor V Leiden mutation, prothrombin gene mutation, protein C deficiency, protein S deficiency, and antithrombin III deficiency. If you have one of these disorders, your doctor will discuss it with you.

Back to top Arrow (up) icon.Icon pointing upwards. Usually means that the containing element can be opened and closed.

Types of Blood Clots

There are 2 types of blood clots that can be dangerous, deep vein thrombosis and pulmonary embolisms. 

Deep vein thrombosis (DVT)

DVT is a blood clot in one of the deep veins, usually in an arm or leg. DVTs are rare in other areas of the body, but they can happen.

When DVT occurs, the clot blocks the normal blood flow through the vein, causing swelling, redness, and pain in the area. If left untreated, new clots can form. This can make the swelling and pain worse. It can also make walking difficult, cause an infection, or lead to skin ulcers.

Pulmonary embolism (PE)

A PE is a blood clot in a blood vessel of the lung. Most of the time it happens when a clot in the leg breaks loose and travels up to a lung.

Once there, the PE can block the blood flow to your lung. It can cause death if it is not treated quickly.

Back to top Arrow (up) icon.Icon pointing upwards. Usually means that the containing element can be opened and closed.

Symptoms of Blood Clots

Blood clots can reduce the flow of blood throughout your body. However, some people with a blood clot don’t feel any symptoms until the problem becomes life threatening.

Symptoms of these blood clots include:

  • Sudden pain and swelling in one arm or leg
  • Difficulty walking due to swelling and pain
  • Sharp chest pain
  • Fast heartbeat
  • Shortness of breath
  • Severe abdominal (belly) pain with or without vomiting and diarrhea

Call your doctor immediately if you notice any symptoms of a blood clot.

Back to top Arrow (up) icon.Icon pointing upwards. Usually means that the containing element can be opened and closed.

Diagnosing Blood Clots

Since some people don’t have any symptoms of blood clots, many blood clots are found when your doctor is looking for something else, such as when you have a scan. Make sure you tell your doctor if you have any symptoms of a blood clot.

If your doctor thinks that you have a blood clot, they will recommend 1 or more of the following tests:

  • A computed tomography (CT) scan of your lungs to look for a PE.
  • An ultrasound of your veins to look for blood clots in your legs or arms.
  • Blood tests to measure the rate at which your blood clots. Blood tests can also see if you have any genes that may increase your risk blood clots. 
Back to top Arrow (up) icon.Icon pointing upwards. Usually means that the containing element can be opened and closed.

Treatment of Blood Clots

Treatment for a blood clot usually includes taking a blood thinner, also known as an anticoagulant. This is the most common treatment for blood clots. Blood thinners help do 2 things:

  • Prevent your body from making new clots.
  • Allow your body’s own system of breaking up clots to work.

Blood thinners can be given:

  • By injection into a vein or under the skin.
  • Orally (by mouth as a tablet).

Your doctor will decide which form is best for you and how long you will need to take it. There are many things that your doctor considers when deciding how long you will need to take a blood thinner. These include if you have been treated for a blood clot in the past, if you have active cancer, or if you’re having chemotherapy.

You may take blood thinners for 3 to 6 months or you may need to stay on them for longer. Some people stay on blood thinners for the rest of their lives.

You will have visits with your doctor every 1 to 3 months while you’re on blood thinners.    


Heparin is a blood thinner used to treat blood clots. If you’re admitted to the hospital for treatment of your blood clot, you may receive heparin by injection into your vein.

Other blood thinners can be injected under your skin. You can get them in the hospital or at home. You can use them alone or in combination with an oral form of blood thinners (see “Warfarin” below). Examples of these medications include enoxaparin sodium (Lovenox®) and fondaparinux (Arixtra®). 

If you need to give yourself injections, your nurse will teach you and your caregiver how to do it. The syringe will have a very short needle and will already be filled with the medication. Your nurse will also give you a resource called How to Give Yourself an Injection Under the Skin With Blood Thinning Medication in a Prefilled Syringe.

Oral blood thinners


One oral form of blood thinner is called warfarin (Coumadin®). It takes several days for it to build up in your body to prevent blood clotting. While this is happening, you will also use the injectable form, which works more quickly to thin your blood. Once your blood is thin enough, you will no longer need to take the injections. You will keep taking warfarin.

While you are on warfarin, you will need to have an international normalized ratio (INR) blood test done. This test measures how long it takes your blood to clot. When you first start taking warfarin, you may need to have the test done at least once a week. The test will be done less often as your blood levels become stable.

Your doctor may change your daily dose of warfarin based on the results of your INR. This is to make sure your blood is thin enough to prevent clots, but not too thin. If your blood is too thin, you may bleed too much if you’re injured.

There are certain foods and medications that can affect your INR level. Speak with your doctor or nutritionist about any food or medication interactions that may happen while you are taking warfarin.

Other oral blood thinners

There are other oral forms of blood thinners available. Your doctor will discuss what is right for you based on your indivdual treatment plan. Examples of the newer blood thinners are rivaroxaban (Xarelto®), apixaban (Eliquis®), and edoxaban (Savaysa®), but there are others.

If you take one of these medications, you don’t need weekly blood tests, but your doctor may recommend you have tests to see how your body is reacting to the medication.


Back to top Arrow (up) icon.Icon pointing upwards. Usually means that the containing element can be opened and closed.

Instructions While You Are on Blood Thinners

There are certain medications that may cause bleeding problems if you take them while you are taking blood thinners. While you are taking blood thinners, do not take the following medications, unless approved by your doctor:

  • Aspirin or products containing aspirin (e.g., Bufferin®, Anacin®)
  • Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen, (Advil®,  Motrin®), or  naproxen sodium (Aleve®)
  • Vitamin E

You can take acetaminophen (Tylenol®) for any pain or discomfort. For more information, read Common Medications Containing Aspirin and Other Nonsteroidal Anti-inflammatory Drugs (NSAIDs).

Some medications may change the way your blood thinner works. Tell your doctor or nurse if you’re taking any medications or have changed medications including:

  • Both over-the-counter and prescription medications
  • Herbal remedies
  • Vitamins
  • Dietary supplements

Tell all your healthcare providers, including your dentist, that you take a blood thinner. If you have any procedures or surgeries planned, you may need to stop taking blood thinners for a period of time. Your doctor will talk with you about this. 

Back to top Arrow (up) icon.Icon pointing upwards. Usually means that the containing element can be opened and closed.

Call Your Doctor or Nurse if You Have:

  • Increased pain, swelling, or both in the arm or leg that has the DVT
  • New pain, swelling, or both in your other arm or leg
  • Shortness of breath
  • Severe headaches or headaches that don’t go away
  • Nose bleeds
  • Bleeding gums
  • Blood in your urine, stool, vomit, or in the mucus that you cough up through your mouth
  • A heavier menstrual flow (period) than usual
  • Bleeding that does not stop
  • Bruising that does not go away
  • Fallen or hurt yourself in any way
  • Plans for any dental procedure or surgery
  • Stopped taking your blood thinner for any reason
  • Any unexpected, unexplained side effects
  • Any questions or concerns
Back to top Arrow (up) icon.Icon pointing upwards. Usually means that the containing element can be opened and closed.

Last Updated