How does this medication work? What will it do for me?

Heparin is a member of the group of medications known as anticoagulants. Anticoagulants reduce the clotting ability of the blood and so prevent harmful blood clots from forming in blood vessels.

Heparin is used to prevent a condition known as deep vein thrombosis (DVT). This condition is associated with the formation of blood clots in the blood vessels in the leg. These blood clots can sometimes travel to the lungs and block blood vessels there, resulting in a serious condition known as pulmonary embolism.

Heparin is also used to prevent blood clotting during dialysis, to prevent clotting of intravenous lines, to prevent unwanted blood clotting during open-heart surgery, and to treat deep vein thrombosis and pulmonary embolism. Heparin is often used after a person has had a heart attack and for people who have unstable angina (chest pain that occurs even at rest). It is also sometimes used to treat strokes that are caused by blood clots.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. As well, some forms of this medication may not be used for all of the conditions discussed here. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

What form(s) does this medication come in?

This medication is available as 1,000 unit/mL and 10,000 unit/mL solutions for injection.

How should I use this medication?

Heparin is given by injection. It can be injected under the skin (subcutaneously) or given into a vein by a procedure called intravenous infusion. The recommended dose and route of administration of heparin varies according to the individual and the condition being treated. Your doctor will choose the dose that is most likely to prevent blood clots but not cause you to bleed easily.

Doses of heparin vary on an individual basis. People taking heparin will need to be monitored by taking blood tests scheduled by their health care provider in order to make sure that they receive the proper amount of medication.

Many things can affect the dose or schedule of medication that a person needs, such as body weight, other medical conditions, and other medications. If the schedule or dose of your medication is different from the ones listed above, do not change the way that you use the medication without consulting your doctor.

It is important to use this medication exactly as prescribed by your doctor. If you miss an injection, take it as soon as possible and continue with your regular schedule. If it is almost time for your next injection, skip the missed dose and continue with your regular dosing schedule. Do not inject a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature, protect it from heat, and keep it out of the reach of children. If you are using the multiple dose vial, do not store it for more than 28 days after the first use.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Do not use this medication if you:

  • are allergic to heparin or any ingredients of this medication
  • are at risk of heparin-induced thrombocytopenia (decreased number of platelets often associated with increased bleeding)
  • are suffering from shock
  • currently have active or uncontrollable bleeding (e.g. acute ulcer or ulcerating carcinoma)
  • have a blood clotting disorder such as hemophilia, Christmas disease, or idiopathic thrombocytopenic purpura
  • have any conditions associated with increased risk of bleeding
  • have had recent surgery or trauma of the spine, nervous system, eye, or ear
  • have severe liver damage

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • bleeding
  • decreased level of platelets (which should be monitored while on heparin)
  • elevation of liver enzymes (which should be monitored while on heparin)

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

  • black, tarry, or bloody stools
  • bleeding from the gums when brushing your teeth
  • blood in urine
  • heavy bleeding or oozing from cuts or wounds
  • itching and burning of soles of feet
  • loss of hair affecting the entire scalp or confined to the temple
  • muscles aches
  • painful erection
  • signs of internal bleeding (vomiting blood)
  • unexplained bruising or purplish areas on the skin
  • unexplained nosebleeds
  • unusually heavy or unexpected menstrual bleeding

Stop taking the medication and seek immediate medical attention if any of the following occur:

  • signs of a severe allergic reaction (such as difficulty breathing; skin rash or hives; swelling of the lips, mouth, or throat)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Blood clotting: This medication is intended to prevent unwanted blood clots, but it can make you bleed more easily. You should be careful when performing activities that increase your risk of bleeding. Tell your doctor of any signs that your blood is not clotting as quickly as usual. Such symptoms may include black and tarry stools, blood in the urine, easy bruising, or cuts that won't stop bleeding.

Kidney problems: If you have kidney problems, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Liver problems: If you have liver problems, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Medical conditions: If you have subacute bacterial endocarditis, blood or blood vessel disorders, severe high blood pressure, indwelling catheters, inaccessible gastrointestinal ulcers, ulcerative colitis, continuous tube drainage of stomach or small intestine, or menstruation, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Osteoporosis: People who receive long-term, daily doses of heparin should be monitored by their doctor for possible development of osteoporosis (brittle bones) or fractures.

Pregnancy: Although heparin is the anticoagulant (blood-thinner) of choice during pregnancy, caution needs to be exercised due to risk of bleeding, especially during the third trimester and immediately after the birth. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: Heparin does not pass into breast milk. Talk to your doctor if you have any questions.

Seniors: Seniors may be at an increased risk of bleeding while using heparin. Your doctor may adjust your dose accordingly.

What other drugs could interact with this medication?

There may be an interaction between heparin and any of the following:

  • antihistamines (e.g. diphenhydramine)
  • any medications that affect blood clotting (e.g., ASA, nonsteroidal anti-inflammatory drugs [e.g., indomethacin, naproxen], warfarin, ticlopidine, clopidogrel, dextran)
  • codeine phosphate
  • dextran
  • digitalis
  • erythromycin
  • ethacrynic acid
  • hydrocortisone sodium succinate
  • neomycin
  • nicotine
  • nitroglycerin (intravenous)
  • penicillins (e.g., ampicillin, piperacillin, penicillin G)
  • polymyxin B
  • promazine hydrochloride
  • protamine
  • quinine
  • streptomycin
  • tetracyclines (e.g. doxycycline, tetracycline)
  • vancomycin
  • vitamin B complex
  • vitamin C

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.