How Does Heparin Work? All About Heparin’s Mechanism of Action
Heparin is an anticoagulant medication used to prevent and treat blood clots. Learn more about heparin’s mechanism of action with this guide from GoodRx.
heparin sodium
Used for Atrial Fibrillation, Deep Vein Thrombosis, Pulmonary Embolism
Used for Atrial Fibrillation, Deep Vein Thrombosis, Pulmonary Embolism
Heparin is a blood thinner that's used to treat and prevent blood clots and other clotting-related conditions. It's given as an injection through the veins or under the skin. Heparin works quickly, but requires regular blood tests to check how well it's working. The dose depends on several things, like your age, weight, and why you need heparin. This medication is typically used for people in the hospital, but there might be certain situations where you can use it at home. It's a safe medication with possible side effects like low red blood cells or bruising. But heparin can cause a serious problem called heparin-induced thrombocytopenia (HIT).
What is Heparin?
What is Heparin used for?
- Prevention and treatment of blood clots in your arms or legs (deep vein thrombosis or DVT) or in your lungs (pulmonary embolism or PE)
- Prevention and treatment of blood clots related to atrial fibrillation (AFib)
- Prevention of blood clots during artery and heart surgery
- Prevention of blood clots after major stomach surgery
- Treatment of consumption coagulopathies (condition of overactive blood clotting)
- Prevention of blood clots during blood transfusions and dialysis
How Heparin works
Heparin is an anticoagulant (or blood thinner). It blocks certain proteins in your blood that are responsible for forming blood clots. This helps prevent blood clots from getting bigger. It also lowers the risk of new blood clots from forming.
Drug facts
| Common Brands | No brands available |
|---|---|
| Drug Class | Anticoagulant |
| Controlled Substance Classification | Not a controlled medication |
| Generic Status | Lower-cost generic available |
| Availability | Prescription only |
More on Heparin essentials
Side effects of Heparin
The following side effects may get better over time as your body gets used to the medication. Let your healthcare provider know immediately if you continue to experience these symptoms or if they worsen over time.
Common Side Effects
The side effects from heparin that you experience will depend on how you receive the medication (through the vein or under the skin) and the dose.
- Anemia (low red blood cells; 5%)
- Bleeding (4%)
- Fever (4%)
- Swelling in arms or legs (2-4%)
- Bruising (3%)
- Nausea (2%)
- Blood in urine (2%)
Heparin serious side effects
Contact your healthcare provider immediately if you experience any of the following.
- Severe bleeding: feeling faint, lightheadedness, dizziness, vomiting blood, bloody or dark-colored stools, severe stomach pain or discomfort
- Heparin-induced thrombocytopenia (HIT) or heparin-induced thrombocytopenia with thrombosis (HITT): skin changes or bruising, shortness of breath, chest pain or tightness, trouble speaking, numbness on one side of your body, vision problems
- Serious allergic reaction: rash; trouble breathing; swelling of the lips, tongue, or face; vomiting; chills; fever
- Blood clots due to stopping heparin too soon: leg or arm (e.g., swelling or redness in arms or legs, skin that's warm to touch); lungs (e.g., trouble breathing, chest pain, cough, irregular heartbeat)
The following Heparin side effects have also been reported
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor or nurse immediately if any of the following side effects occur:
Less common
Abdominal or stomach pain or swelling
back pain or backaches
bleeding from the gums when brushing teeth
blood in the urine
coughing up blood
dizziness
headaches, severe or continuing
heavy bleeding or oozing from cuts or wounds
joint pain, stiffness, or swelling
menstrual bleeding, unexpected or unusually heavy
unexplained bruising or purplish areas on the skin
unexplained nosebleeds
vomiting of blood or material that looks like coffee grounds
Rare
Blood under the skin (blood blister) at the place of injection
chills or fever
fast or irregular breathing
irritation, pain, redness, or ulcers at the place of injection
itching and burning feeling, especially on the bottom of the feet
nausea or vomiting
numbness or tingling in the hands or feet
pain, coldness, or blue color of the skin on the arms or legs
peeling of the skin
puffiness or swelling of the eyelids or around the eyes
shortness of breath
skin color change, especially near the place of injection or in the fingers, toes, arms, or legs
tearing of the eyes
tightness in the chest
trouble with breathing
After you stop using this medicine, it may still produce some side effects that need attention. During this period of time, check with your doctor immediately if you notice the following side effects:
Black, tarry stools
bleeding gums
blood in the urine or stools
pain in the chest, groin, or legs, especially calves of legs
pinpoint red spots on the skin
severe headaches of sudden onset
sudden loss of coordination
sudden shortness of breath for no apparent reason
sudden slurred speech
sudden vision changes
unusual bleeding or bruising
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
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$71.48
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$4.89
Pros and cons of Heparin
Pros
- Works well to treat several types of blood clotting problems
- Works quickly (immediately when given as a quick injection through the vein; within 2 hours when given under the skin)
- Can use during pregnancy
- Antidote (or reversal agent) available if you have severe bleeding from heparin
Cons
- Must have blood tests done on a regular basis
- Only available as an injection, which can be uncomfortable
- Can cause a serious low platelet condition called heparin-induced thrombocytopenia (HIT)
- Not a good option for people who have pork allergies
Pharmacist tips for Heparin
- Mark your appointments on your calendar to see your provider and get your blood work done. This makes sure your providers can properly check to make sure heparin is working well for you and is safe for you.
- Make sure to tell your provider about all of the medications you're taking before starting heparin, especially if you take aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs) (e.g., ibuprofen (Advil), naproxen (Aleve)). These medications can raise your risk for bleeding.
- It's important to let your surgeon and dentist know that you're taking heparin before any surgery is scheduled. This medication can raise your risk of bleeding during procedures. Your provider might give you specific instructions around the time of your scheduled surgery about when to stop using heparin.
- Heparin can make it easier to bruise or bleed, and it can take longer for your body to stop any bleeding. Make sure to contact your provider if you have any unusual bleeding (e.g., blood in urine or stool, coughing up blood, vomiting blood) or bruising while taking this medication.
- If you fall and hit your head hard, get medical help right away, especially if you have dizziness or severe headache. You might need a head scan to see whether you have a brain bleed.
- Heparin can cause you to have very low platelets, sometimes occurring with blood clots. These serious problems can happen even several weeks after stopping heparin. Seek emergency medical help if you experience skin changes or bruising, shortness of breath, chest pain or tightness, trouble speaking, numbness on one side of your body, or vision problems.
More tips for using heparin at home:
- Your provider might allow you to give yourself heparin injections under your skin at home. Follow your provider's directions or carefully read the instructions for use (for the prefilled syringes) so you can give yourself the injections safely and properly. Make sure you have the correct strength and dose of heparin to prevent medication errors. Contact your provider or pharmacist if you have any questions on how to use this medication.
- Inject heparin into the fat tissue under the skin of your stomach; this is the area that's most commonly used. Always rotate your injection sites for each dose. Repeated injections to the same area can lead to pain and damaged skin. Never inject heparin into your muscle.
- Before injecting heparin, always check to make sure the medication is clear and colorless. If it's cloudy, discolored, or has many particles, don't use it. Contact your provider or pharmacist to see whether it's possible to get a replacement.
- Each heparin vial or prefilled syringe provides a single dose of medication. Throw away the syringe after using, even if there's still some medication remaining inside. Prefilled syringes don't contain any preservatives to keep germs out of the medication once they're opened.
- After giving yourself the medication, throw away the used syringe and needle in a sharps container or something made of heavy-duty plastic (e.g., empty milk carton, laundry detergent bottle). This lowers the risk of needle-stick injuries. Don't throw them away in your trash can. Learn more about how to throw away your sharps on the FDA's website.
- Store heparin at room temperature. Don't put the medication into the refrigerator.
Risks and warnings for Heparin
Heparin can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.
Risk of bleeding
- Risk factors: Taking other medications that raise the risk for bleeds | History of bleeding problems | Liver problems | Severe high blood pressure | Female and 60 years of age or older | Being on your period
Taking heparin can raise your risk for bleeds. Your risk is higher if you're also taking other medications that can cause bleeding. If you do have a serious bleed from heparin use, your provider might be able to give you a medication called protamine to reverse the effects of heparin. Let your provider know if you have a fall, head injury, or other kinds of physical injury. They might need to check you for bleeding inside your body. Get medical help right away if you have dark or tarry stool, bleeds that are difficult to stop, or any unusual bleeding.
Low platelet counts and clotting problems
- Risk factors: History of heparin-induced thrombocytopenia (HIT) or heparin-induced thrombocytopenia with thrombosis (HITT)
Heparin can cause your platelet counts to go down. In rare cases, a low platelet count can occur along with a life-threatening condition called heparin-induced thrombocytopenia (HIT). HIT happens when the immune system makes antibodies that affect the function of platelets. This can cause blood clots to form in various parts of the body and lead to blockages in your veins or arteries, a condition called heparin-induced thrombocytopenia with thrombosis (HITT).
These platelet and clotting problems can occur up to several weeks after stopping heparin. If your platelets become very low or if you experience any blood clots during or after treatment, it's likely that heparin will be stopped and your providers will consider a different blood thinner for you if needed. Make sure you keep up with your lab work so your provider can keep track of your platelet counts. Get medical help right away if you experience any symptoms of blood clots during or after heparin treatment.
Risk of serious breathing problem in infants (gasping syndrome)
- Risk factors: Newborns | Infants with low birth weight | Pregnant females | Breastfeeding
Benzyl alcohol is one of the preservatives found in certain heparin products. This preservative can cause a rare, but serious and sometimes life-threatening medical condition called gasping syndrome. This condition is more likely to happen in newborns and infants with low birth weight. If you're pregnant or breastfeeding, talk with your provider before receiving heparin, since your baby could potentially be exposed to benzyl alcohol in the womb or through your breast milk. Tell your provider if your child experiences any major weight changes while receiving heparin. Get medical attention right away if your child has symptoms, such as gasping, slowed heart rate, clammy skin, dizziness, seizures, slurred speech, or weakness in an arm or leg.
Severe allergic reactions
- Risk factors: Pork allergy
Severe allergic reactions to heparin are possible, including life-threatening reactions like facial swelling, shock, and anaphylaxis (e.g., closing of the throat). Also, let your provider know if you have a pork allergy before taking this medication because heparin is made from porcine (pigs). If you notice difficulty breathing, a choking sensation, swelling around your eyes, swelling of the lips or tongue, dizziness, or nausea after using heparin, get medical attention right away.
Heparin dosage
The average cost for 60 vials of 1ml of 5000 units/ml of Heparin is $41.38 with a free GoodRx coupon. This is 89.96% off the average retail price of $412.25. 
Syringe
Vial
Syringe| Dosage | Quantity | Price as low as | Price per unit |
|---|---|---|---|
| 1ml of 5000 units/ml | 24 syringes | $39.46 | $1.64 |
| 0.5ml of 5000 units/0.5ml | 120 syringes | $162.50 | $1.35 |
Vial| Dosage | Quantity | Price as low as | Price per unit |
|---|---|---|---|
| 1ml of 5000 units/ml | 60 vials | $41.38 | $0.69 |
| 10ml of 1000 units/ml | 1 vial | $7.18 | $7.18 |
| 1ml of 10000 units/ml | 10 vials | $21.43 | $2.14 |
| 5ml of 10000 units/ml | 1 vial | $10.56 | $10.56 |
| 30ml of 1000 units/ml | 1 vial | $8.28 | $8.28 |
| 1ml of 1000 units/ml | 1 vial | $4.89 | $4.89 |
| 10ml of 5000 units/ml | 3 vials | $21.51 | $7.17 |
| 4ml of 10000 units/ml | 6 vials | $25.75 | $4.29 |
| 2ml of 1000 units/ml | 25 vials | $15.52 | $0.62 |
| 1ml of 20000 units/ml | 2 vials | $12.23 | $6.12 |
| 0.5ml of 5000 units/ml | 60 vials | $141.90 | $2.37 |
| 30ml of 30000 units/ml | 1 vial | $8.35 | $8.35 |
| 10ml of 10000 units/ml | 1 vial | $7.33 | $7.33 |
| 2ml of 2000 units/ml | 1 vial | $7.15 | $7.15 |
Typical dosage for Heparin
The dose of heparin varies from one person to another. Your provider will calculate your dose based on your age, weight, and why you need heparin. The dose will also depend on certain lab test results, including complete blood count (CBC) and those measuring how long it takes for your blood to clot.
Heparin is given as an injection into the veins (intravenous or IV) or under the skin (subcutaneous or SC). It's typically given in a hospital or at home by a healthcare provider. But if your provider says it's safe to do so, they might allow you to give yourself under-the-skin heparin injections at home.
Prevention of blood clots The typical dose is 5,000 units injected under the skin every 8 to 12 hours.
Treatment of blood clots The dose is based on your weight, the reason you need heparin, and certain lab values that measure how long it takes your blood to clot. It also depends on whether heparin is given to you as a continuous infusion through the veins, an injection into the veins at regular time intervals, or an injection under the skin.
Hospitals typically have a specific protocol or program in place that outlines how to monitor and change the heparin dose based on these lab values so it works well and is as safe for you as possible.
The following are general dosing options and how often heparin is given:
- Adults
- Continuous infusion through the veins: After the first dose, the medication is infused continuously.
- Intermittent injection into the veins: After the first dose, the medication is given IV every 4 to 6 hours.
- Injection under the skin: First, the medication is given IV once, followed by an injection under the skin once. Then, the medication is injected under the skin every 8 hours or every 12 hours.
- Children
- Continuous infusion through the veins: After the first dose, the medication is infused continuously.
More on Heparin dosage
Interactions between Heparin and other drugs
Heparin may interact with certain medications or supplements. Always let your doctor and pharmacist know about any other medications or supplements (including prescribed and over-the-counter medications, vitamins, and dietary or herbal supplements) that you are currently taking. The list below does not include all possible drug interactions with Heparin. Please note that only the generic name of each medication is listed below.
Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are receiving this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.
- Defibrotide
- Oritavancin
- Telavancin
Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
- Abciximab
- Aceclofenac
- Acemetacin
- Alipogene Tiparvovec
- Alprostadil
- Alteplase, Recombinant
- Amtolmetin Guacil
- Anagrelide
- Anistreplase
- Antithrombin, Recombinant
- Apixaban
- Argatroban
- Aspirin
- Bemiparin
- Betrixaban
- Bivalirudin
- Bromfenac
- Bufexamac
- Cangrelor
- Caplacizumab-yhdp
- Cefamandole
- Cefoperazone
- Celecoxib
- Chamomile
- Choline Salicylate
- Cilostazol
- Citalopram
- Clonixin
- Clopidogrel
- Collagenase, Clostridium histolyticum
- Dabigatran Etexilate
- Dalteparin
- Danaparoid
- Desvenlafaxine
- Dexibuprofen
- Dexketoprofen
- Dextran
- Diclofenac
- Diflunisal
- Dipyridamole
- Dipyrone
- Drotrecogin Alfa
- Droxicam
- Edoxaban
- Enoxaparin
- Epoprostenol
- Eptifibatide
- Escitalopram
- Etodolac
- Etofenamate
- Etoricoxib
- Felbinac
- Fenoprofen
- Fepradinol
- Feprazone
- Floctafenine
- Flufenamic Acid
- Fluoxetine
- Flurbiprofen
- Fluvoxamine
- Garlic
- Ginkgo
- Ibrutinib
- Ibuprofen
- Iloprost
- Indomethacin
- Inotersen
- Ketoprofen
- Ketorolac
- Levomilnacipran
- Lornoxicam
- Loxoprofen
- Lumiracoxib
- Meclofenamate
- Mefenamic Acid
- Meloxicam
- Milnacipran
- Morniflumate
- Moxalactam
- Nabumetone
- Nadroparin
- Naproxen
- Nepafenac
- Niflumic Acid
- Nimesulide
- Nimesulide Beta Cyclodextrin
- Nintedanib
- Nitroglycerin
- Omadacycline
- Orlistat
- Oxaprozin
- Oxyphenbutazone
- Papaya
- Parecoxib
- Paroxetine
- Pentosan Polysulfate Sodium
- Phenylbutazone
- Piketoprofen
- Piracetam
- Piroxicam
- Pranoprofen
- Prasugrel
- Proglumetacin
- Propyphenazone
- Proquazone
- Reteplase, Recombinant
- Rivaroxaban
- Rofecoxib
- Sarecycline
- Selexipag
- Sertraline
- St John's Wort
- Streptokinase
- Sulfinpyrazone
- Sulindac
- Tan-Shen
- Tenecteplase
- Tenoxicam
- Tiaprofenic Acid
- Ticagrelor
- Ticlopidine
- Tirofiban
- Tolfenamic Acid
- Tolmetin
- Trazodone
- Treprostinil
- Urokinase
- Valdecoxib
- Venlafaxine
- Vilazodone
- Vorapaxar
- Vortioxetine
Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
- Chondroitin
- Coenzyme Q10
- Curcumin
- Dong Quai
- Ginger
- Palifermin
- Vitamin A
- Warfarin
How much does Heparin cost?
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Heparin (generic)
$4.89
Heparin contraindications
Contraindications are specific health conditions or situations in which a person should not take a medication due to safety concerns. If you have any of the following conditions or if any of the following apply to you, let your healthcare provider know because Heparin will not be safe for you to take.
- History of heparin-induced thrombocytopenia (HIT) or heparin-induced thrombocytopenia with thrombosis (HITT)
- Pork allergy
- Uncontrolled bleeding (except when it's due to disseminated intravascular coagulation)
- Unable to complete blood tests for monitoring
What are alternatives to Heparin?
There are a number of medications that your doctor can prescribe in place of Heparin. Compare a few possible alternatives below.
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Heparin images
