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Home > Wellness > Health Library > Low-Molecular-Weight Heparins for Deep Vein Thrombosis
Normally, when an injury that causes
bleeding occurs, the body sends out signals that cause blood to clot at the
wound, and then the clot naturally breaks down as the wound heals. A person prone to
abnormal clotting has an imbalance between clot formation and clot breakdown.
Anticoagulant medicines prevent new clots from forming and
prevent existing clots from growing (extending) by stopping the production of
certain proteins that are needed for blood to clot. They do not break up or
dissolve existing blood clots.
Low-molecular-weight heparins can be
used to treat a
deep vein thrombosis. When used to either prevent or
treat a blood clot, they are given by injection just under the skin once or
twice each day. Unlike with other forms of anticoagulants, periodic blood tests
are usually not needed to monitor how well the medicines are working.
Two types of heparin are
available for treatment of deep vein thrombosis.
Unfractionated heparin is given in the hospital. Low-molecular-weight heparin (LMWH) can be self-injected at home, which
usually is more convenient.
To treat deep vein thrombosis, you might start taking low-molecular-weight heparin and warfarin. Often both medicines are started at the same time, and then heparin is stopped
after warfarin becomes effective. Some people may take
low-molecular-weight heparin long-term instead
Low-molecular-weight heparin can be
used to treat or prevent a deep vein thrombosis.1 When used for treatment,
low-molecular-weight heparins prevent new blood clots from forming and prevent
existing clots from getting larger.
All medicines have side effects. But many people don't feel the side effects, or they are able to deal with them. Ask your pharmacist about the side effects of each medicine you take. Side effects are also listed in the information that comes with your medicine.
Here are some important things to think about:
Bleeding: Call 911 or other emergency services right away if:
Call your doctor right away if you have unusual bleeding:
If you are injured, apply pressure to stop the bleeding. Realize that it
will take longer than you are used to for the bleeding to stop. If you can't get the bleeding to stop, call your doctor.
Allergic reaction.Call 911 or other emergency services right away if you have:
Call your doctor if you have:
Injection sites. Side effects often happen at injection sites. These side effects include:
Reference for a full list of side effects. (Drug Reference is not available in
If you take heparin, you need to take extra steps to avoid bleeding problems.
For more information, see:
Long-term use of heparin typically is not
recommended. It requires one or two injections each day. And long-term use is linked with
Medicine is one of the many tools your doctor has to treat a health problem. Taking medicine as your doctor suggests will improve your health and may prevent future problems. If you don't take your medicines properly, you may be putting your health (and perhaps your life) at risk.
There are many reasons why people have trouble taking their medicine. But in most cases, there is something you can do. For suggestions on how to work around common problems, see the topic Taking Medicines as Prescribed.
If you are pregnant, you can take heparin during your pregnancy. Heparin has not been shown to affect the fetus.
For more information, see Pregnancy and the Increased Risk of Developing Blood Clots.
Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor if you are having problems. It's also a good idea to know your test results and keep a list of the medicines you take.
Complete the new medication information form (PDF)(What is a PDF document?) to help you understand this medication.
Antithrombotic drugs (2011). Treatment Guidelines From The Medical Letter, 9(110): 61–66.
May 14, 2012
E. Gregory Thompson, MD - Internal Medicine & Jeffrey S. Ginsberg, MD - Hematology
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