Treatments and drugs

By Mayo Clinic Staff

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

If genetic tests have confirmed that you have factor V Leiden, but you haven't had any blood clots, then your doctor probably won't prescribe blood thinners on a regular basis. But you may be given a course of blood thinners to reduce your risk of DVT during high-risk situations, such as having surgery or being hospitalized.

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. It can be administered directly into a vein (intravenously) or under the skin (subcutaneously). You can inject yourself with some forms of heparin, including enoxaparin (Lovenox) and dalteparin (Fragmin). Heparin is considered safe to take during pregnancy.

    Possible risks of heparin include excess bleeding and allergic reaction. Heparin doesn't have a standard dose, so it requires regular blood tests and adjustments to get the right dose for you.

  • Warfarin (Coumadin, Jantoven). This anticoagulant comes in pill form, so it's easier to take than heparin. Warfarin may cause birth defects, so it isn't usually recommended during pregnancy, especially the first trimester. Bleeding is the most common side effect of warfarin.

    This drug interacts with many other medications and herbs, so be sure to check with your doctor or pharmacist before taking anything else. As with heparin, there isn't a standard dose for warfarin, so you'll need regular blood tests and dose adjustments while taking warfarin.

New oral blood thinners

Three new oral medications have been approved by the Food and Drug Administration for the prevention and treatment of blood clots in certain people. They have an advantage over warfarin, as they don't require blood test monitoring or dose adjustments. Bleeding complications are the most serious side effect of these medications, but that risk appears to be lower with these drugs than with warfarin:

  • Dabigatran (Pradaxa)
  • Rivaroxaban (Xarelto)
  • Apixaban (Eliquis)

Excessive bleeding caused by these new oral blood thinners can't be easily reversed. Bleeding caused by heparin and warfarin, on the other hand, can be quickly reversed.

These newer medications also haven't been well-studied in pregnant women. They may interact with certain medications, but do have far fewer food or drug interactions compared with warfarin.

Talk with your doctor about the risks and benefits for you of new oral blood thinners compared with warfarin.

Follow-up care

If you're taking an anticoagulant medication that increases the risk of excessive bleeding, your doctor will follow you closely. You'll have blood tests to help your doctor make sure your blood is capable of clotting enough to stop bleeding if you bruise or cut yourself.

Factor V Leiden during pregnancy

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 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.

July 14, 2015