Heparin is an injectable medicine that is used to prevent harmful blood clots. It has been used by millions of patients for over 50 years, making it one of the oldest drugs still in widespread use. Despite its long clinical history, however, heparin is associated with several potential side effects, some of which are serious. Patients who might have a need to take heparin should familiarize themselves with the risks of the drug.
Background
Pharmaceutical grade heparin is isolated from organs of slaughtered animals, such as pigs and cows. It is available only with a doctor's prescription, and is used to prevent blood clots from forming in the veins, arteries and lungs. It is also used to prevent blood clotting during open-heart surgery, heart bypass surgery and kidney dialysis. Regular blood tests are performed to assure that the drug is working appropriately in patients.
Bleeding Risk
Because heparin acts an anticoagulant to stop blood from clotting, the drug may cause bleeding episodes during its use, or even several weeks after its use. Certain medicines, such as aspirin or other NSAIDs (non-steroidal anti-inflammatory drugs), can increase the risk of bleeding with heparin. Patients on heparin who experience unusual bruising or bleeding, or bleeding that won't stop, should seek medical attention immediately.
Other Side Effects
Heparin is administered as an injection into the skin; therefore the most common side effect is mild pain or irritation at the injection site. Other less-common side effects may include stomach pain or swelling, back pain, joint pain, headache, skin rashes, and coldness or blue color of the skin on the arms and legs. Osteoporosis or loss of bone density, and severe allergic responses characterized by breathing difficulties, hives or swelling, are also linked to heparin.
A potentially serious side effect is heparin-induced thrombocytopenia or HIT. In this condition, heparin induces the formation of antibodies that target and destroy key blood cells called platelets. If left untreated, HIT can result in heart attack, stroke or death.
At Risk Populations
Patients with the highest risk of developing severe heparin side effects include those over 60 years old and/or individuals with a history of bleeding disorders, low platelet counts, high blood pressure, stomach or intestinal disorders, or liver disease. Pregnant women should not take heparin because the Food and Drug Administration (FDA) classifies it as a "Class C" medication.
Overdose
Minor heparin overdoses are usually treated by stopping further administration of the drug. In severe cases of heparin overdose, characterized by excessive bleeding (hemorrhage), doctors may inject a drug called protamine, which binds to the heparin and neutralizes it.
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