How It Works
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.
Why It Is Used
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.
You might take heparin for a few days. Then you will likely take another anticoagulant as a pill for at least 3 months. Some people may take low-molecular-weight heparin long-term.
How Well It Works
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.
- This allows the normal body systems to dissolve the clots that are already formed.
- This also reduces the risk of pulmonary embolism.
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:
- Usually the benefits of the medicine are more important than any minor side effects.
- Side effects may go away after you take the medicine for a while.
- If side effects still bother you and you wonder if you should keep taking the medicine, call your doctor. He or she may be able to lower your dose or change your medicine. Do not suddenly quit taking your medicine unless your doctor tells you to.
Call911or other emergency services right away if you have:
Call your doctor if you have:
Call 911 or other emergency services right away if you have:
Call your doctor now or seek immediate medical care if you have:
- Any abnormal bleeding, such as:
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.
Injection sites. Side effects often happen at injection sites. These side effects include:
See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)
What To Think About
If you take heparin, you need to take extra steps to avoid bleeding problems.
For more information, see:
Blood Thinners Other Than Warfarin: Taking Them Safely
Long-term use of heparin typically is not recommended. It requires one or two injections each day. And long-term use is linked with osteoporosis.
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.
Advice for women
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.
Primary Medical ReviewerE. Gregory Thompson, MD - Internal Medicine
Specialist Medical ReviewerJeffrey S. Ginsberg, MD - Hematology
Current as ofMarch 12, 2014