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Heparin (unfractionated)

I am taking _____units of heparin_____a day

You have been prescribed heparin (UFH) to help prevent or treat blood clots. You may also be taking heparin in combination with warfarin (Coumadin®). Always talk to your doctor before changing medications or before stopping heparin. Follow your doctor or healthcare provider's instructions carefully in order to prevent bleeding or the formation of serious clots.

Heparin is known as an anticoagulant which is a drug that lengthens the time it takes for your blood to clot. This makes it harder for clots to form in your blood vessels and heart, and stops existing clots from getting larger. If you are going to be taking heparin, there are some facts you need to know about this medication.

Important facts to remember......

  • Take the exact amount prescribed at the same time each day. If you miss a dose, take it as soon as you remember. DO NOT give yourself an "extra" injection.

  • Make sure to keep all appointments for blood related laboratory tests as your doctor needs to check them to see if the medication is working for you and to check for side effects.

  • Remember to tell your surgeon or dentist that you are taking heparin. You may need to stop taking it ahead of time if you need to have dental work or a surgical procedure. The effects of heparin last for about 12 hours.

  • This medication is given as an injection under the skin. Your doctor or healthcare provider will either give you the injection or show you how to inject the medication. Make sure you fully understand how to inject the medication under the skin and NOT into a muscle before you take heparin home.

How do I adminster heparin?

  1. Heparin is supplied as a single-vial and must be drawn up in a syringe. It is injected under the skin.

  2. Check the vial for cracks, and make sure the solution is clear and particle-free. Do not use the vial if any of these characteristics are present.

  3. Before injection, clean the injection site with rubbing alcohol and expel any air bubbles in the syringe.

  4. Change the location of the injection site daily.

  5. Do not inject this medication into muscle, and do not rub the injection site after use to avoid bruising.

  6. Do not reuse the needle and syringe; keep away from children, and dispose off this medication properly as directed by your doctor or pharmacist.

  7. Store this medication at room temperature (59-86 degrees Farenheit). Protect this medication from light, heat, and moisture (Do not store this medication in the bathroom).


 Call your doctor or healthcare provider immediately if you......

  • Have any bleeding or bruising that is not normal. Tell your doctor or healthcare provider if you have any of the following: dark, tarry or bloody stools; red or rust-colored urine; nose bleeds; easy bruising, unusual weakness; bruising or bleeding at an incision site following surgery or surgical procedure.

  • Develop any hives, swelling of your tongue or face, chest pain, and trouble breathing. These are serious side effects of heparin that may require immediate attention.

  • Have any severe abdominal pain, severe chest pain or shortness of breath, headache, eye problems (blurred vision/loss of vision), severe leg pain (calf or thigh). These may be a sign of a blood clot.

  • Start any new medications, including over-the-counter (OTC) products and dietary supplements such as warfarin (Coumadin®), clopidogrel (Plavix®), ticlodipine (Ticlid®), cilostazol (Pletal®), dipyridamole (Persantine®), pain relievers such as aspirin, ibuprofen (Motrin®, Advil®), naproxen (Aleve®, Naprosyn®), indomethacin (Indocin®), and fish oils. These drugs increase your risk of bleeding when taken together with heparin.

  • Are pregnant or planning to become pregnant. Although heparin is safe in pregnancy, it should be used if necessary and under special care of your doctor or health care professional.

Commonly Asked Questions~

Why do I need to take this medication?

Clots may form in blood vessels of the legs and then travel to the lungs where they can become stuck and cause harm to you. Heparin has been prescribed for you because you have a condition or conditions that increase your chance of forming blood clots. These conditions include:

  • Recent surgery, especially hip fracture, hip or knee replacement, and abdominal surgery

  • Current or previous clot in the leg of clot in the lung

  • Cancer or major illness requiring hospitalization

  • Recent heart attack

  • Irregular heart beat

  • Artificial heart valve

How long will I have to take this medication?

It is usually used for a few days, but it may be used for a longer period of time. Depending on your condition, it may be used for as long as your doctor or healthcare provider thinks you will be at risk for forming clots.

Who should not receive heparin?

Patients with...

  • Active major bleeding

  • Low platelets

  • If heparin lowered your platelet count

  • Allergy to heparin or related pork products

  • Allergy to low molecular weight heparin (LMWH)

What side effects may occur?

The most serious side effect of heparin is bleeding. Some signs to watch for:

  • Bleeding, that takes a long time to stop, from a minor injury such as a cut; bleeding from your gums or nose

  • A lot of bruising or unexplained bruising

  • Red or rust-colored urine

  • Black or tarry stools, or blood in the stool

  • Purple-blue coloring or the toes or fingers

  • Dizziness or faintness

  • WOMEN: long lasting or a lot of menstrual or vaginal bleeding

Let you doctor or healthcare provider know immediately if you develop any of the symptoms mentioned above .

Side effects that do not require medical attention (unless long lasting or bothersome) include:

  • Pain and/or irritation at the injection site

  • Rash and/or itching at the injection site

  • Fever

How can I lower my risk of bleeding?

Since it takes longer for your blood to clot when you are taking heparin, you will need to take some steps to avoid injury:

  • Shave with an electric razor instead of a blade

  • Use a soft-bristled toothbrush and floss gently with waxed floss

  • Do not walk barefoot and do not trim foot corns or foot calluses yourself

  • Do not take part in activities tat have a high risk of injury, such as skiing, football, or other contact sports


If you have additional questions, arrangements can be made for a pharmacist to speak to you.

Information is provided as a service of the University Medical Center at Princeton's Department of Pharmacy Services


-Baxter Healthcare Corporation. Heparin package insert. Deerfield, IL; January 2008

-Micromedex® Healthcare Series (Internet database). Greenwood Village, Colo:Thomson Healthcare. Updated periodically. Available at (Accessed on August 12, 2008).

2nd edition. October 2008   Created by Cynthia DePiano, Pharm.D. and Daniel Abazia, Pharm.D.,BCPS

The health information provided in this publication is for general purposes and is not intended to constitute medical advice. The information should not be used for diagnosis or treatment, nor should it be used to replace the advice of licensed healthcare professionals. Health concerns or questions should be discussed with you physician. If you have any concerns about your health, please contact your healthcare provider.