Heparin (Intravenous, Subcutaneous)


Heparin is a medicine available by prescription to help prevent the development of blood clots in people with certain medical conditions, including heart, lung and blood vessel conditions, or people who are having a medical procedure that raises the possibility of blood clots developing, like kidney dialysis, blood transfusions, bypass surgery and open-heart surgery.

It's also taken in small doses to prevent blood clots from forming in some patients, particularly those who need to recover in bed for long periods. Heparin can be taken to diagnose, as well as treat, a severe blood problem known as disseminated intravascular coagulation. In addition, Heparin is taken in small doses to prevent the development of blood clots in catheters (little plastic tubes used to draw blood or administer medication) that are forgotten in the veins over some time.

Heparin can halt the growth of blood clots that have formed in blood vessels, but can't help reduce the size of blood clots that have developed previously.

Heparin is part of a class of medicines known as anticoagulants, which work by reducing the ability of blood to clot.

This medicine comes in injectable form and is given through an IV into a vein or subcutaneously (under the skin) by a healthcare provider.

Common Heparin side effects include injection site reactions and bleeding.

Conditions Treated

  • Blood clot prevention
  • Blood clot in lung
  • Severe blood clotting problem
  • Lung embolism
  • Acute heart syndrome
  • Prevention of deep vein thrombosis

Type Of Medicine

  • Anticoagulant

Side Effects

Medications may bring on side effects. The side effects may be temporary or permanent, mild or severe.

The following side effects aren't experienced by everybody who uses Heparin. If you're worried about side effects, please discuss this medication's risks and benefits with your doctor. Contact your healthcare provider if you have these effects and they're bothersome or severe. Your pharmacist can give you advice you on how to control them.

The following side effects were reported by about 1% of patients taking the medication. Many of them can be controlled and some may disappear on their own eventually:

  • Bleeding
  • Increase of liver enzymes (these should be checked while you're on Heparin)
  • Reduced level of platelets (these should be checked while you're on Heparin)

While most of the effects below happen less often, they might lead to serious issues if you don't get medical attention.

Check with your physician promptly if you suffer any of the effects below:

  • Bloody, tarry, or black stools
  • Blood in urine
  • Painful erection
  • Muscle aches
  • Bleeding from gums when you brush your teeth
  • Heavy oozing or bleeding from wounds and cuts
  • Burning and itching of soles
  • Unexplained nosebleeds
  • Purplish areas on skin or unexplained bruising
  • Vomiting blood (internal bleeding signs)
  • Unexpected or unusually heavy menstrual bleeding
  • Loss of hair on the whole scalp or limited to the temple

Stop taking Heparin and seek medical care immediately if you suffer any of these signs of a very serious allergic reaction: hives or skin rash, difficulty with breathing, swelling of the throat, mouth or lips.

Some people may develop other side effects not mentioned above. Please see your healthcare professional if you develop any symptom that concerns you while you're using Heparin.


Heparin is available as a liquid (solution) to be injected straight into a vein (intravenously) or deeply below the skin (subcutaneously), as well as a less concentrated (dilute) liquid that's injected into a number of intravenous catheters. Your healthcare professional shouldn't inject this medication into a muscle.

This medication is occasionally injected one to six times daily and is sometimes administered as a continuous, slow injection into a vein.

Heparin may be administered by any healthcare provider, such as a nurse, or you may be instructed on how to inject it at home by yourself. If you'll be injecting this medication by yourself, a healthcare professional will teach you how to give yourself the injection. Ask your nurse, pharmacist, or doctor if you don't understand these instructions or have any queries about where you should inject this medication, how to give yourself the injection and how to discard used syringes and needles after you inject Heparin.

If you'll be giving yourself the Heparin injection, carefully follow the instructions on the prescription label, and ask your pharmacist or doctor to explain whatever part you don't understand. Please use this medication exactly as instructed. Don't take less or more of Heparin or take it more frequently than directed by your doctor.

Heparin solution is available in a variety of strengths and taking the wrong strength can cause serious issues. Before giving yourself a Heparin injection, check the label of the package to ensure it's the right strength of Heparin liquid that your physician prescribed. If it's not the right strength, don't take the medication and call up your pharmacist or doctor at once.

Your doctor may reduce or increase your Heparin dose in the course of your treatment. If you'll be giving yourself the injection, ensure you know the quantity of medicine you should use.

Heparin injectable liquid is used for temporary treatment. It carries serious risks if not taken as prescribed.

If you don't take Heparin at all or stop taking it suddenly, an existing clot could worsen or you may get a blood clot. These blood clots may be fatal.

If you don't take Heparin on schedule or miss doses, your medicine may not work properly or may stop working altogether. For Heparin to work effectively, you need to have a certain amount of it in your body all the time.

If you use too much Heparin, hazardous levels of the medication could get into your body, which may cause serious bleeding. This may be fatal. Symptoms of a Heparin overdose include:

  • Brown or pink urine
  • Bruising easily
  • Dizziness
  • Weakness
  • Headaches
  • Vomit that resembles coffee grounds or contains blood
  • Blood clots or coughing up blood
  • Uncontrollable or severe bleeding
  • Tarry, dark stool (may indicate stomach bleeding)
  • Unexpected bleeding/prolonged bleeding (e.g. frequent nosebleeds, unusual bleeding from gums, heavier than normal menstrual periods)

If you suspect you've taken excess Heparin, call your local poison control agency or doctor right away. If you have severe symptoms, visit your nearest emergency room or call 911 right away.

If you've missed a Heparin dose, take it immediately you remember. Never try to compensate for missed doses by taking double doses at the same time. This may lead to hazardous side effects, including serious bleeding.

Here's how to know if Heparin is working: your current blood clot should go away, or you should not have a blood clot. For more information about this, consult your healthcare professional.


Heparin may interact with other medicines, herbal supplements and vitamins you may be using. An interaction refers to an instance where a substance alters the way a medication works. This may be hazardous or may stop the medication from working properly.

To avoid interactions, your healthcare professional should carefully control all of your medicines. Be sure to report to your doctor all medications, herbal supplements and vitamins you're using. To find out how Heparin might interact with whatever you're using, talk to your pharmacist and doctor.

Examples of medications that may interact with Heparin are as follows:

Interactions that may increase the chances of side effects

Using Heparin with some medications can cause easy bruising or increase your chances of bleeding. Examples of these medications include:

  • Dextran
  • Aspirin
  • Hydroxychloroquine
  • Antithrombin III (human)
  • NSAIDs, such as Naproxen, Ibuprofen and Celecoxib
  • Antiplatelet medications, such as Dipyridamole, Clopidogrel and Abciximab
  • Herbal supplements, including fish oil, garlic and ginkgo biloba

Interactions that can decrease the effectiveness of Heparin

When taken with Heparin, some medications decrease the effectiveness of Heparin. Examples of such drugs include:

  • Nicotine
  • Digoxin
  • Tetracycline antibiotics, including Minocycline and Doxycycline
  • Nitrates, including Isosorbide, Nitroglycerin and Mononitrate
  • Antihistamines, including Diphenhydramine

Heparin may bring about bleeding in the stomach. Ingesting alcohol every day may raise the risk of suffering this side effect. Please talk to your healthcare professional about the amount of alcohol that is safe to consume while you're using Heparin.

Smoking can make Heparin less effective. Make sure your doctor knows if you use tobacco products or smoke before taking Heparin.

Heparin contains sodium. Speak to your physician if you're on a diet that restricts salt while taking Heparin.


Heparin comes with a number of warnings.

Allergy warning

Heparin may cause a very severe allergic reaction with the following symptoms: chills, fever, hives, rash, death of skin tissue at injection site, burning, itching, shortness of breath and swelling of tongue, throat, face or lips. If you develop these symptoms, visit your nearest emergency room or call 911.

Don't take Heparin if you've ever suffered an allergy after using it. Heparin is obtained from animal tissue. Therefore, it should be used cautiously by people with an allergy to it or to proteins from pigs. If you're allergic to Heparin, don't take it, as it could cause death.

Warnings for peeople with these health conditions:

For people with allergies to pig proteins

Don't take Heparin. As this medication is derived from pork tissue, it may cause a deadly allergy in people who are allergic or sensitive to other kinds of pig proteins.

For people with out of control hypertension

You're at a greater risk of bleeding if you take Heparin. Consult your physician before taking Heparin.

For people with clotting or bleeding problems

If you have unusual bleeding or any condition that increases your risk of bleeding, you shouldn't use Heparin, as it could put you at an even greater risk. Use Heparin cautiously.

For people who've had bleeding or stomach ulcers

If you have existing stomach ulcers, don't take Heparin. It may cause dangerous bleeding and worsen your ulcers. If you don't have stomach ulcers now but have a history of them, using Heparin increases your chances of bleeding. Please consult your doctor before taking Heparin.

For people with kidney disease

Taking Heparin may increase your chances of bleeding if you've had kidney disease before or have serious kidney disease now. Consult your physician before taking Heparin.

For people with liver disease

Taking Heparin may raise your chances of bleeding if you've had liver disease before or have serious liver disease now. Consult your physician before taking Heparin.

For people with asthma or allergies to sulfite

People who have asthma may have allergies to sulfites. Sulfites may cause a potentially fatal allergic reaction in certain people. Some varieties of Heparin have sulfites. Please talk to your physician about taking a sulfite-free form of Heparin.

Warnings For Other Persons

For pregnant women

Studies done in animals have revealed that Heparin can harm the fetus if the mother takes the medication. However, there hasn't been enough research done in humans to be sure how Heparin might affect an unborn child.

Please consult your doctor if you plan to get pregnant or are pregnant. Heparin should be taken only if the possible benefit outweighs the possible risk. Ask your physician if taking the preservative-free form of Heparin might be a better option than the one with benzyl alcohol.

If you get pregnant while taking Heparin, call your physician straight away.

For breastfeeding women

Heparin is not likely to pass into the mother's milk and be ingested by a baby being breastfed. Consult your physician about the right way to nurse your baby while you're using Heparin.

Some varieties of Heparin contain a preservative known as benzyl alcohol, which can make the central nervous system of some babies slow down. It may also cause changes in blood chemistry of some infants and troubled breathing. These effects may be fatal. If you're breastfeeding, consult your physician about taking preservative-free Heparin.

For children

Heparin hasn't be studied in children. Dosage requirements will depend on clinical experience. Infants and newborns should be given preservative-free Heparin. Benzyl alcohol is thought to cause serious effects and even fatalities in infants and newborns.

For older adults

If you're older than 60, you could be at a greater risk of bleeding. This medication also raises your bleeding risk, so your physician may get you started on a lower dose.


Keep Heparin at room temperature, away from heat and moisture.

Use the disposable syringe and needle just once. Follow any local or state laws about disposing of used syringes and needles. Use a 'sharps' puncture-proof disposal container (consult your pharmacist about how to discard the container and where to buy one).

Keep this container away from pets and children.


Honor all of your laboratory and doctor appointments. Your doctor will arrange some laboratory tests to assess your response to Heparin. You may be asked to check for blood in your stool using a test kit at home.

Before taking any lab test, tell the lab personnel and your doctor that you're taking Heparin.

Don't allow anybody else to take your medicine. If you've got any questions about refilling your Heparin prescription, ask your pharmacist.

Your doctor may decrease or increase your Heparin dose during your treatment. If you'll be giving yourself the injection, make sure you know the quantity of medicine you should use.

Heparin injectable liquid is used for short-term treatment. It carries serious risks if not taken as prescribed.

Heparin injection shouldn't be used to clean out (flush) an IV (intravenous) catheter. There's a separate Heparin product available that you can use as a catheter lock flush.

If you're allergic to Heparin, don't take it. Also, don't take this medication if you have a serious deficiency of platelets in blood or if you have unrestrained bleeding.

Before taking Heparin, inform your physician if you have an infection of your heart, high blood pressure, hemophilia or other bleeding condition, liver disease, an intestinal or bleeding disorder or if you're on your monthly period.

Heparin can make you have bleeding spells while you're taking it and for weeks after you stop taking it. Call up your physician right away if you have easy bruising and unusual bleeding, e.g. tarry or black bloody stools, nosebleeds or any endless bleeding.

Some medications may increase your chances of bleeding while you're taking Heparin, including Aspirin or other non-steroidal anti-inflammatory drugs like Ibuprofen (Motrin, Advil), Ketoprofen (Orudis), Naproxen (Treximet, Naprelan, Naprosyn, Aleve), Celecoxib (Celebrex), Indomethacin (Indocin), Ketorolac (Toradol), Piroxicam (Feldene), Diclofenac (Solareze, Pennsaid, Flector Patch, Voltaren, Cambia, Cataflam, Arthrotec), Meloxicam (Mobic), Nabumetone (Relafen), Mefenamic Acid (Ponstel) and others.

Report all sorts of medication you use to your doctor. This includes over the counter, prescription, herbal and vitamin products. Don't start using a new medicine without informing your doctor first.

Women who are older than 60 are at a greater risk of having bleeding episodes while taking Heparin.