Heparin is used to treat and prevent blood clots caused by certain medical conditions or medical procedures. Heparin is also used before surgery to reduce the risk of blood clots.

Do not use heparin injection to flush (clean out) an intravenous (IV) catheter. A separate heparin product is available to use as catheter lock flush. Using the wrong type of heparin to flush a catheter can result in fatal bleeding.

Heparin may also be used for purposes not listed in this medication guide.

You should not use this medicine if you are allergic to heparin or pork products, or if you have:

• a history of low platelets in your blood caused by using heparin or pentosan polysulfate;
• a severe lack of platelets in your blood; or
• uncontrolled bleeding.

You may not be able to use heparin if you are unable to receive routine blood-clotting tests at the proper intervals during treatment.

Tell your doctor if you have ever had:

• an infection of the lining of your heart (also called bacterial endocarditis);
• severe or uncontrolled high blood pressure;
• a bleeding or blood clotting disorder;
• a stomach or intestinal disorder;
• liver disease;
• if you use a blood thinner (warfarin, Coumadin, Jantoven) and you have routine "INR" or prothrombin time tests; or
• if you are having a menstrual period.

Tell your doctor if you are pregnant or plan to become pregnant. You may need to use a form of heparin that does not contain a preservative.

You should not breastfeed while using heparin.

Use Heparin (Injection) exactly as directed on the label, or as prescribed by your doctor. Do not use in larger or smaller amounts or for longer than recommended.

Get emergency medical help if you have signs of an allergic reaction: nausea, vomiting, sweating, hives, itching, trouble breathing, swelling of your face, lips, tongue, or throat, or feeling like you might pass out.

Heparin may cause you to bleed more easily, which can be severe or life-threatening. You may also have bleeding on the inside of your body. Seek emergency medical attention if you have:

• skin warmth or discoloration;
• chest pain, irregular heartbeats;
• shortness of breath, dizziness, anxiety, sweating;
• any unusual bleeding or bruising;
• severe pain or swelling in your stomach, lower back, or groin;
• dark or blue-colored skin on your hands or feet;
• nausea, vomiting, loss of appetite;
• unusual tiredness;
• any bleeding that will not stop; or
• nosebleed, blood in your urine or stools, black or tarry stools, or coughing up blood or vomit that looks like coffee grounds.

Heparin can cause you to have bleeding episodes while you are using it and for several weeks after you stop.

Bleeding may be more likely in older adults, especially women over 60 years of age

Stop using heparin and call your doctor at once if you have:

• skin changes where the medicine was injected;
• fever, chills, runny nose, or watery eyes;
• easy bruising, unusual bleeding, purple or red spots under your skin; or
• signs of a blood clot--sudden numbness or weakness, problems with vision or speech, swelling or redness in an arm or leg.

Common side effects may include:

• unusual bleeding or bruising;
• uncontrolled bleeding;
• allergic reactions; or
• abnormal liver function tests.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Avoid medication errors by using only the form and strength your doctor prescribes.