Lovenox (Enoxaparin) vs. Heparin for Blood Clots

Medically reviewed by Alex Yampolsky, PharmD

Lovenox (enoxaparin) and heparin are both prescription blood thinners primarily used to prevent or treat certain types of blood clots, such as pulmonary embolisms (PEs) and deep vein thrombosis (DVT).

While used for similar purposes, they have some differences, including their dosing schedules and how they are taken. They are both effective options, but understanding their differences can help determine which one might better suit you.

This article compares Lovenox and heparin by discussing their similarities and differences, including their dosing, side effects, precautions, and more.

<p>Getty Image / <a href="" data-component="link" data-source="inlineLink" data-type="externalLink" data-ordinal="1">Bloomberg</a> / Contributor</p>

Getty Image / Bloomberg / Contributor

Lovenox vs. Heparin: Key Similarities and Differences

Lovenox and heparin are injectable medications used to prevent and treat blood clots.

However, Lovenox is a type of medication called low molecular weight heparin (LMWH), and heparin is a type called unfractionated heparin (UFH).

The dose and frequency of administration may vary between the two drugs. Heparin requires frequent dosing and can be administered either through the vein (intravenously) or under the skin (subcutaneously).

In contrast, Lovenox is given once or twice daily and only administered subcutaneously (under the skin).

Heparin requires frequent monitoring of blood-clotting tests compared to Lovenox, while Lovenox does not require regular blood draws to check blood-clotting levels. Both medications require regular checkups for signs and symptoms of bleeding, such as bruising or coughing up blood.

While used for similar purposes, there are cases in which one drug might be better than the other. For example, heparin might be better for people with low body weight or kidney problems. It’s important to talk to the healthcare provider to discuss what treatment suits each person based on their health conditions.


  • Low molecular weight heparin (LMWH)
  • Dosed once or twice daily
  • Given subcutaneously
  • Does not require regular blood tests
  • Can be given at home or by a healthcare provider


  • Unfractionated heparin (UFH)
  • Requires more frequent dosing
  • Given intravenously or subcutaneously
  • Requires frequent blood clotting tests
  • Usually given in a clinical setting

Lovenox vs. Heparin: Uses

The FDA approved Lovenox for:

Heparin is indicated for:

  • Prevention and treatment of DVT and PE
  • Treatment of acute and chronic consumption coagulopathies (a type of bleeding disorder)
  • Treatment of blood clots associated with atrial fibrillation (A-fib)
  • Prevention and treatment of blood clots in the arteries
  • Prevention of blood clotting in surgery

How Do They Work?

Both heparin and Lovenox work to prevent or treat blood clots by slowing down the process of blood clot formation. However, due to their structures, there are some differences in how they work (mechanism of action).

Both medications have similar targets but stick to each target at different levels.

Heparin blocks the natural process that causes blood to clot by blocking clotting proteins found in the blood. These proteins are called antithrombin and Factor Xa (pronounced as Factor 10a). Both are key players in the clotting cascade.

By blocking these proteins, heparin prevents the formation of large and harmful blood clots that can cause severe issues like strokes or heart attacks. Essentially, it keeps the blood flowing smoothly and prevents it from getting too sticky.

Lovenox has a more targeted approach to controlling blood clotting. It binds primarily to Factor Xa. It also blocks other proteins involved in clot formation but mainly focuses on Factor Xa. By disrupting this section of the cascade, Lovenox helps maintain thinner blood.

Dosage: How Are They Given?

Lovenox and heparin have different dosage forms, strengths, administration methods, and frequency.

Lovenox is available in prefilled syringes, multidose vials, and single-use vials in various strengths. In contrast, heparin is available in vials and premixed bags.

Lovenox is injected using a small needle just under the skin. It is typically given once or twice daily, depending on the indication. You can self-administer it at home with proper training from a healthcare provider.

Heparin is administered intravenously or subcutaneously, with the dosage adjusted based on body weight and blood test results. It is typically administered in a healthcare setting, such as a hospital or infusion center.

Your healthcare provider determines the duration and frequency of administration.

The length of treatment with blood thinners varies based on indication. Your provider will determine how long you receive treatment based on your medical condition.

In most cases, treatment typically begins with injections during a hospital stay and is then transitioned to blood thinners that can be taken by mouth.

Lovenox vs. Heparin: Which Is More Effective?

Researchers have conducted studies to compare the effectiveness of Lovenox and heparin. Overall, both medications are effective in treating and preventing blood clots.

Results from studies differ based on the medical condition being treated, as follows:

  • One study showed that Lovenox worked better for reducing complications during percutaneous coronary intervention (PCI).
  • A review of four clinical trials showed that Lovenox was more effective at preventing blood clots in hospitalized people without increasing the risk of major bleeding.
  • In another study, Lovenox was more effective in preventing DVT after stroke.
  • However, other studies have suggested that heparin and Lovenox are similarly effective for many of their uses.

Always talk to your healthcare provider about which option is right for you. A medical expert will consider factors like your medical history, the reason for using the medication, cost, administration preferences, and potential side effects.

Side Effects

Lovenox and heparin, although they belong to the same class of medications, can exhibit some different side effects.

Common Side Effects

Lovenox and heparin are both blood-thinning medications used to prevent blood clots. It’s important to note that the side effects can vary from person to person, and not everyone will experience the same symptoms.

Here is a list of common side effects for Lovenox, heparin, and both.


  • Increased risk of bleeding
  • Local bruising
  • Thrombocytopenia (low platelets)

Lovenox only:

  • Anemia
  • Nausea
  • Pain at the injection site
  • Liver injury

Heparin only:

  • Bone fractures with long-term use

Severe Side Effects

While severe side effects are uncommon, it’s important to be aware of the potential risks. Keep in mind that these reactions are rare, and not everyone will experience them.

Severe side effects associated with both medications include:

  • Hemorrhage (severe bleeding)
  • Heparin-induced thrombocytopenia (HIT)
  • Allergic reactions

Heparin-induced thrombocytopenia is a condition in which heparin or Lovenox can unexpectedly cause a low platelet count in the blood. Platelets are tiny cells that help the blood to clot. In HIT, the body attacks these platelets, leading to a risk of more blood clots forming instead of preventing them.

It’s essential to recognize and manage HIT promptly, as it can be a serious condition requiring adjustments in treatment to keep the blood clotting properly. Once an individual has experienced HIT, they will no longer be candidates to take either heparin or Lovenox.


Talking about precautions with your healthcare provider will help ensure you are given the right medication and take it safely. Certain groups of people might be able to take Lovenox or heparin.

Who Should Not Use Lovenox or Heparin?

People with the following indications should avoid Lovenox and heparin:

  • A known allergy to enoxaparin or heparin
  • A history of severe bleeding disorders or certain medical conditions
  • A case of active bleeding
  • Low platelets
  • A past case of HIT

Additionally, people with severe kidney problems and low body weight should not use Lovenox.

What Increases the Risk of Side Effects?

To reduce the risk of side effects, the following precautions should be taken when on Lovenox and heparin:

  • Taking other blood-thinning medications along with Lovenox or heparin can increase the risk of bleeding.
  • People with liver or kidney problems may be more prone to side effects.
  • Any recent surgeries or injuries should be discussed with a healthcare provider, as they may affect the safety of these medications.

Can You Take Lovenox or Heparin While Pregnant or Breastfeeding?

Both Lovenox and heparin are considered safe during pregnancy, especially for females with a higher risk of blood clots.

Heparin is acceptable for breastfeeding people because heparin does not pass into breast milk. On the other hand, Lovenox does pass into breast milk but is still considered safe due to poor absorption by mouth.

However, pregnant or breastfeeding individuals must consult with their healthcare provider, as the decision to use these medications during pregnancy depends on individual health conditions and the potential risks versus benefits.

Drug Interactions

Knowing how different medications can interact is essential to make sure you use them safely and effectively.

Common pain-relieving medications, like aspirin or nonsteroidal anti-inflammatory drugs (NSAIDs) such as Advil or Motrin (ibuprofen), can increase the risk of bleeding. Using these medications while on heparin or Lovenox makes the bleeding effects stronger.

Other blood thinners, such as warfarin or apixiaban, can also increase the risk of bleeding. By using more than one blood thinner, multiple factors are making your blood less likely to clot, which could lead to excessive bleeding.

When taking a blood thinner, it is crucial to exercise caution with substances that may lead to falls, which can increase the risk of bleeding. In the event of a significant fall, seek prompt medical attention, as you could be at risk for internal bleeding.

These medications do not typically interact with alcohol.

Tell your healthcare provider about all the medications you take, including over-the-counter (OTC) or prescription medications, and dietary or herbal supplements.

This conversation can help prevent complications and ensure that the combination of medications is safe and effective for you. Always follow your healthcare provider’s advice and ask them about aspects of your medication that you’re unsure of.


Lovenox and heparin are both effective options to prevent and manage blood clots. They work similarly but have several differences, including their dosing and where they are administered.

Individuals must consult their healthcare providers for personalized recommendations and guidance when considering using Lovenox or heparin, as each person’s circumstances vary.

The author would like to recognize and thank Norma Ponce, PharmD, MHA, for contributing to this article.

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