Treatments and drugs

By Mayo Clinic Staff

Doctors generally use blood-thinning (anticoagulant) medications, such as warfarin (Coumadin), heparin or low molecular weight heparin to treat people who develop blood clots.

If genetic tests have confirmed that you have a factor V mutation, but you haven't had any blood clots, then your doctor probably won't routinely prescribe blood thinners unless you're in a high-risk situation, such as being hospitalized for surgery or other medical reasons. In that case, you may receive preventive doses of blood thinners during your hospital stay.

If you have a blood clot, standard initial treatment involves a combination of heparin and warfarin. Your doctor will discontinue the heparin after the initial treatment and continue the warfarin. How long you need to take medication will depend on the circumstances of your thrombosis.

  • Heparin. This anticoagulant medication works more quickly than warfarin does, but must be monitored closely due to the risk of excess bleeding. This medication can be administered directly into a vein (intravenously) or under the skin (subcutaneously). Other forms of heparin — enoxaparin (Lovenox) and dalteparin (Fragmin) — are known as low molecular weight heparin, which you can inject yourself. Heparin is considered safe to take during pregnancy. Possible risks of heparin include excess bleeding and allergic reaction.
  • Warfarin (Coumadin). This anticoagulant comes in pill form, so it's easier to take than heparin is. Warfarin may cause birth defects, so it isn't usually recommended during pregnancy, especially not during the first trimester. Bleeding is the most common side effect of warfarin. This drug interacts with numerous other medications and herbs, so be sure to check with your doctor or pharmacist before taking anything else.
  • Dabigatran (Pradaxa). This oral medication, which isn't specifically approved by the Food and Drug Administration (FDA) for the treatment of blood clots, also thins the blood, but doesn't require the same monitoring that heparin and warfarin do. Bleeding is the most serious side effect associated with dabigatran. Unlike warfarin, there's no easy way to reverse excessive bleeding caused by dabigatran. No reliable studies have been conducted on pregnant women, so the drug should be used only if the benefits outweigh the potential risk. Dabigatran interacts with some medications, such as antibiotics or antifungal drugs, especially in people with kidney problems.
  • Rivaroxaban (Xarelto). This is a blood-thinning medication. Like dabigatran, it's an oral medication that doesn't require monitoring. It currently FDA approved for the prevention of blood clots in certain people, but is not specifically approved for the treatment of blood clots. Bleeding is the most common side effect, and the effects of this drug can't be easily reversed. Rivaroxaban hasn't been well-studied in pregnancy, so it should be used with caution in expectant mothers. This drug can interact with a number of medications, such as some antibiotics, antifungal medications and antiviral drugs. Check with your doctor before combining any medications.

Ongoing monitoring

If you're taking anticoagulant medication that can be monitored, your doctor will monitor your dose with blood tests to be sure your blood is capable of clotting enough to stop bleeding if you bruise or cut yourself.

Pregnancy considerations

Most women with factor V Leiden have normal pregnancies. However, the risk of blood clots during pregnancy is higher. Pregnant women with factor V Leiden need close medical supervision throughout their pregnancies. There's currently no evidence that preventive treatment with blood-thinning medications would be effective enough to outweigh the potential risks of using these drugs during pregnancy or delivery.

When your baby is born, routine testing of newborns isn't currently recommended because blood clots are rare in children and teens, and chances are good that your child may never have any signs or symptoms related to factor V Leiden.

Sep. 06, 2012

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