This medication is used to prevent and treat blood clots. It may be used to prevent and treat blood clots in the lungs/legs (including in patients with atrial fibrillation). It may be used to treat certain blood clotting disorders. It may also be used to prevent blood clots after surgery, during dialysis, during blood transfusions, when collecting blood samples, or when a person is unable to move for a long time. Heparin helps to keep blood flowing smoothly by making a certain natural substance in your body (anti-clotting protein) work better. It is known as an anticoagulant.

This section contains uses of this drug that are not listed in the approved professional labeling for the drug but that may be prescribed by your health care professional. Use this drug for a condition that is listed in this section only if it has been so prescribed by your health care professional.

This drug may also be used to reduce the risk of blood clots in people who have had certain types of heart attack, or who have a certain type of chest pain called unstable angina.

Read the Patient Information Leaflet if available from your pharmacist before you start using heparin and each time you get a refill. If you have any questions, ask your doctor or pharmacist.

This medication is given by injection into a vein or under the skin as directed by your doctor. Do not inject this medication into a muscle. The dosage and how often you use it are based on your medical condition, weight, and response to treatment.

Heparin comes in many strengths. Serious (sometimes fatal) injuries have occurred when the wrong strength was used. Check that you are using the correct strength and dose before injecting this medication.

If you are giving this medication to yourself at home, learn all preparation and usage instructions from your health care professional. Before using, check this product for particles or discoloration. If either is present, do not use the liquid. Learn how to store and discard medical supplies safely.

If you are injecting heparin into a vein, flush the catheter/line with normal saline before and after infusing drugs that interact with heparin such as doxorubicin, droperidol, ciprofloxacin, and mitoxantrone.

If you are injecting heparin under the skin, clean the skin you are going to inject into (the injection site) with rubbing alcohol. Change the injection site each time to lessen injury under the skin.

Use this medication regularly to get the most benefit from it. To help you remember, use it at the same times each day.

Your doctor may direct you to switch to an anticoagulant taken by mouth (such as warfarin). Use this medication and any new medication exactly as directed by your doctor.

Mild pain/redness/irritation at the injection site may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.

Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Tell your doctor right away if you have any serious side effects, including:

• swelling at injection site
• bone pain
• easily broken bones

This medication can cause bleeding if its effect on your clotting proteins is too much. Tell your doctor right away if you develop any signs of serious bleeding, including unusual pain/swelling/discomfort, prolonged bleeding from cuts or gums, frequent nosebleeds, unusually heavy/prolonged menstrual periods, unusual/easy bruising, dark urine, black stools, severe headache, unusual dizziness.

This drug may rarely cause certain serious (rarely fatal) clotting problems (heparin-induced thrombocytopenia-HIT or heparin-induced thrombocytopenia and thrombosis-HITT). This can occur during treatment and up to several weeks after treatment with heparin has stopped. You should not use heparin again if you have HIT or HITT. If you notice any of the following very serious side effects, get medical help right away:

• pain/loss of feeling in the arms/legs
• change in color of the arms/legs
• chest pain
• trouble breathing
• confusion
• weakness on one side of the body
• trouble speaking
• vision changes

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including:

• fever
• chills
• rash
• itching/swelling (especially of the face/tongue/throat)
• severe dizziness
• trouble breathing

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Before using heparin, tell your doctor or pharmacist if you are allergic to it; or to pork products; or to pentosan polysulfate sodium; or if you have any other allergies. This product may contain inactive ingredients (such as benzyl alcohol found in some brands), which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of:

• bleeding/blood problems (such as low platelet count, hemophilia)
• high blood pressure (hypertension)
• heart problems (such as infection of the heart, heart attack)
• recent surgery/procedure
• cancer
• stomach/intestinal ulcers or tube drainage
• liver disease
• high level of potassium in the blood

To lower the chance of getting cut, bruised, or injured, use caution with sharp objects like razors and nail cutters, and avoid activities such as contact sports.

This medicine may cause stomach bleeding. Daily use of alcohol while using this medicine will increase your risk for stomach bleeding. Limit alcoholic beverages. Ask your doctor or pharmacist about how much alcohol you may safely drink.

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

This medication contains sodium. Consult your doctor or pharmacist if you are on a salt-restricted diet or if you have a condition that could worsen if you have more salt (such as heart failure).

Older adults, especially women over 60 years of age, may be more sensitive to the side effects of this drug, especially bleeding.

During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.

This medication does not pass into breast milk. Consult your doctor before breastfeeding.

See also How to Use section.

Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.

Some products that may interact with this drug include:

• mifepristone
• oritavancin
• telavancin
• other drugs that can cause bleeding/bruising (including "blood thinners" such as apixaban/dabigatran)

This medication is sometimes used together with other drugs that have "blood thinning" or anti-platelet effects such as aspirin, clopidogrel, or warfarin. If your doctor prescribes a combination of these drugs, your doctor will monitor you closely to minimize your risk of bleeding. Keep all medical and lab appointments.

Check all prescription and nonprescription medicine labels carefully since many medications contain pain relievers/fever reducers (NSAIDs such as ibuprofen, naproxen, or aspirin) that can increase the risk of bleeding when used with heparin. However, if your doctor has told you to take low-dose aspirin to prevent heart attack or stroke (usually 81-162 milligrams a day), you should keep taking the aspirin unless your doctor tells you not to. Ask your doctor or pharmacist for more details.

Cigarette smoking decreases blood levels of this medication. Tell your doctor if you smoke or if you have recently stopped smoking.

This medication may interfere with certain lab tests (such as certain liver function tests, prothrombin time), possibly causing false test results. Make sure lab personnel and all your doctors know you use this drug.

If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call 1-800-222-1222. Canada residents can call 1-844-764-7669. Symptoms of overdose may include: easy/unusual bruising, easy/unusual bleeding (such as frequent nosebleeds), blood in urine, black stools.

Do not share this medication with others.

Lab and/or medical tests (such as complete blood count, activated partial thromboplastin time, potassium blood level) should be done before you start using this medication and while you are using it. Keep all medical and lab appointments. Consult your doctor for more details.

It is important to get each dose of this medication as scheduled. If you miss a dose, ask your doctor or pharmacist right away for a new dosing schedule. Do not double the dose to catch up.

Consult the product instructions and your pharmacist for storage details. Keep all medications away from children and pets.

Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.

Your condition can cause complications in a medical emergency. For information about enrolling in MedicAlert, call 1-888-633-4298 (US) or 1-800-668-1507 (Canada).