Lovenox side effects and how to avoid them

Common Lovenox side effects | Serious side effects | Lovenox and bleeding | How long do side effects last? | Warnings | Interactions | How to avoid side effects

Lovenox is a brand-name medication that is injected under the skin (subcutaneously) once or twice a day to prevent or treat blood clots. It is used to treat people diagnosed with a blood clot, such as a deep vein thrombosis (DVT) or pulmonary embolism (PE). It is also used to prevent blood clots in people who are hospitalized, have unstable angina (chest pain), have had a heart attack, or who are undergoing hip replacement surgery, knee replacement surgery, or abdominal surgery. The active ingredient in Lovenox, enoxaparin sodium, belongs to a family of anticoagulants (“blood thinners”) called low molecular weight heparins (LMWH). All blood thinners are potentially hazardous drugs and Lovenox is no exception. To minimize risks, people taking Lovenox should be familiar with possible side effects, drug interactions, warnings, and especially the ways to prevent problems when taking this drug.

RELATED: What is Lovenox?

Common side effects of Lovenox

The most common side effects of Lovenox are:

• Bleeding 
• Anemia
• Fever
• Swelling in the extremities
• Liver problems
• Nausea
• Blood in the urine or stools
• Diarrhea
• Injection site reactions

Serious side effects of Lovenox

The most serious side effects associated with Lovenox are:

• Severe bleeding (major hemorrhage)
• Bleeding around the spinal cord (epidural or spinal hematoma)
• Severe anemia
• Low platelet counts (thrombocytopenia) or platelet death (thrombocytosis)
• High potassium
• Severe liver problems
• Severe allergic reactions

Lovenox and bleeding

Lovenox blocks the ability of the body to form blood clots, which are the body’s way of stopping bleeding. Most people taking Lovenox will experience more frequent bleeding and bruising than normal, but these usually are minor episodes. 

Minor bleeding and bruising can be a nuisance, but major bleeding episodes or internal bleeding can be life-threatening. Healthcare professionals consider major bleeding as losing enough blood to require medical treatment or reducing the body’s hemoglobin levels by two percent. Internal bleeding is a potentially serious problem because it can’t be seen. Major bleeding episodes were experienced by up to 13% of people taking Lovenox, and a fraction of those included bleeding in the brain, bleeding in the abdomen, and bleeding around the spinal cord. In addition, blood loss lowers both red blood cell counts and hemoglobin, so anemia is a common side effect that is reported in up to 16% of clinical trial participants. 

It is important for people taking enoxaparin or their caregivers to know the symptoms of internal bleeding, which can happen in the head, digestive system, urinary tract, and other areas in the body. At any sign of internal bleeding, contact a healthcare provider for medical advice or go to an emergency room. Enoxaparin has an antidote called protamine sulfate that a healthcare professional can inject into the bloodstream to partly neutralize its effects.

How long do Lovenox side effects last?

Lovenox has a half-life between four and a half to seven hours, so its most common side effects, such as bleeding and bruising, should start getting better somewhere between half a day and one day. The risk of major bleeding episodes will pass in a day or two after the last dose has been taken.

Some serious side effects, such as major bleeding episodes, anemia, and severe allergic reactions, may take longer to resolve and may require medical interventions. Severe internal bleeding could have lifelong consequences if it occurs in the brain or spinal cord.

Lovenox contraindications and warnings

Anticoagulants like Lovenox have a high risk of causing injury due to bleeding. Some medical or physical conditions can increase that risk. 

Abuse and dependence

Enoxaparin does not cause physical dependence or withdrawal symptoms. The U.S. Food and Drug Administration (FDA) does not consider enoxaparin to be a drug with the potential for abuse. 

Overdose

If too much Lovenox is taken, the risk for severe bleeding goes up. Immediate medical attention is needed unless more than 12 hours have passed since the last dose was injected. In that case, call a poison helpline or a healthcare provider for medical advice. In case of an overdose, a healthcare professional may administer an antidote, protamine sulfate, to reverse the effects of enoxaparin.

Restrictions

Severe bleeding is the most common hazard with anticoagulants like Lovenox. For that reason, any pre-existing condition involving bleeding problems or an increased risk of bleeding may prevent healthcare providers from prescribing Lovenox. Because of the bleeding risks, Lovenox is never be prescribed to people with:

• Active major bleeding: Anticoagulants will worsen any current bleeding crisis.

• Heparin-induced thrombocytopenia: Heparin anticoagulants can cause platelet cell counts to drop (thrombocytopenia). Platelets are the blood cells that form blood clots. Any person who has recently experienced a decline in platelets when taking heparin drugs will not be able to take Lovenox. 

• Circulating antiplatelet antibodies: In some people, the immune system attacks platelets as if they were foreign invaders. As a result, they frequently experience low platelet levels and bleeding problems. 
• Allergies to Lovenox, pork products, or benzyl alcohol

Some pre-existing conditions can increase the risk of Lovenox side effects, but this medication can still be used with heightened monitoring. These pre-existing conditions include:

• A high risk for bleeding. Before prescribing anticoagulants, healthcare providers assess the risk for bleeding. If the risk is too high, they may not prescribe Lovenox or they may need to closely monitor the patient for bleeding problems. Some risk factors for bleeding include uncontrolled high blood pressure, recent surgery, a history of gastrointestinal bleeding or ulcers, blood clotting problems, diabetic retinopathy, kidney dysfunction, bleeding disorders, bacterial endocarditis, hemorrhagic stroke, and liver problems. .

• Pregnant women with a mechanical heart valve. Pregnant women with a prosthetic heart valve have a higher risk of forming blood clots when taking Lovenox. The FDA advises very close monitoring of pregnant women with prosthetic heart valves for coagulation problems.

• Epidural or spinal anesthesia. People receiving a spinal block or spinal puncture and those who have a spinal catheter after surgery are at an increased risk of bleeding around the spinal cord. These procedures cannot be performed until the blood levels of enoxaparin are low.

• Kidney problems. Enoxaparin is partly eliminated from the body through the kidneys. People with decreased kidney function will need to be monitored for side effects such as bleeding.

• Low body weight. Low-weight women (less than 100 pounds) and low-weight men (less than 125 pounds) are more likely to experience side effects, so they will be monitored more closely for bleeding and other problems.

• Excess weight. People with a BMI greater than 30 have in general a higher risk of forming blood clots. However, there are no guidelines for adjusting Lovenox dosages for this population, so healthcare providers will monitor these patients closely for blood clots.

Pregnancy and nursing

Healthcare providers use Lovenox cautiously in pregnant and nursing women. Although enoxaparin crosses the placenta, animal studies and clinical studies have shown no risk for developmental problems in a fetus. However, when a pregnant woman is taking enoxaparin, there is an increased risk that the baby will be born with bleeding problems or with neonatal gasping syndrome, an allergic condition caused by hypersensitivity to benzyl alcohol, a preservative used in Lovenox vials. To prevent neonatal gasping syndrome, pregnant women will be given Lovenox without the benzyl alcohol preservative. 

Lovenox is prescribed to women who are breastfeeding. In limited studies, nursing infants have not shown any adverse effects or developmental problems. 

Children

Lovenox is not FDA-approved for use in children or adolescents.

Seniors

In clinical trials, people older than 65 years were more likely to experience bleeding problems at higher doses. This risk increased with increasing age. A healthcare professional will more carefully monitor older patients for side effects particularly if they have decreased kidney function or a low body weight.

Lovenox interactions

The most serious side effect of Lovenox is bleeding, so its most serious drug interactions involve drugs that also cause bleeding, such as:

• Defitelio (defibrotide), another anticoagulant, and mifepristone, used to end a pregnancy, are never combined with Lovenox because of the potential for major bleeding episodes.
• Other anticoagulants
• Aspirin and aspirin-containing medicines
• Nonsteroidal anti-inflammatory drugs (NSAIDs)
• Types of antidepressants called selective serotonin reuptake inhibitors (SSRIs) or serotonin and norepinephrine reuptake inhibitors (SNRIs)
• Omega-3 fatty acids

How to avoid Lovenox side effects

Realistically, taking any blood thinner is risky because of the potential for bleeding episodes. Taking Lovenox is necessary, though, to prevent more serious and possibly lethal blood clots. There are a few things that people can do to minimize the risk and increase the benefits of taking Lovenox.

1. Tell the prescribing healthcare provider about all medical conditions

The first line of defense against side effects is to make sure the prescribing doctor has a complete medical history. In particular, make sure the doctor knows about: 

• Any history of bleeding problems, including:
• Digestive system bleeding
• Ulcers
• Any bleeding disorder
• A bacterial infection of the heart
• Stroke caused by bleeding
• High blood pressure
• Eye problems due to diabetes
• Recent surgery
• Any history of problems when taking heparin
• Any history of spinal surgery, spinal taps, or spinal catheters
• Liver problems
• Kidney problems
• Pregnancy or pregnancy plans
• Breastfeeding or breastfeeding plans

2. Tell the prescribing healthcare provider about all medications being taken

Many side effects, including bleeding, are caused by combining Lovenox with other drugs. Always keep a list of all drugs being taken, including over-the-counter drugs and supplements, and give that list to the prescriber as well as the pharmacist when getting any prescription. For Lovenox, healthcare providers particularly need to know about:

• Aspirin or aspirin-containing products
• NSAIDs such as ibuprofen or naproxen
• Any blood thinners being taken such as warfarin, Plavix (clopidogrel), or heparin drugs

3. Take Lovenox as directed

If Lovenox is being injected at home, follow all the instructions given by the healthcare provider. Do not change the dose or the dosing schedule. A healthcare provider should show you or a caregiver how to make the injection. Make sure these instructions are understood and followed when administering an injection.

4. Know how to administer Lovenox

Another proven way to prevent adverse reactions is to know how to take any medication that is prescribed. The prescribing healthcare provider, hospital, or pharmacist may provide a patient information sheet about Lovenox. Read this sheet carefully. If you don’t receive a patient information sheet, Lovenox prefilled syringes are packaged with a drug information sheet. Unfortunately, it is written for healthcare professionals and can be difficult to read. However, it has valuable information about how to give an injection (in the Dosage and Administration section) and good advice (in the Patient Counseling section).

5. Use ice packs and pressure to stop bleeding or bruising

Lovenox does not prevent blood clots, it simply slows down the formation of blood clots. When bleeding or bruised, you can help the body form a blood clot by applying an ice pack to the spot. The cold causes blood vessels to tighten, restricting blood flow to the cut or bruise and allowing a blood clot to form more easily. If ice packs aren’t available, applying pressure to the bleeding area also restricts blood flow.

6. Get medical help if bleeding is a problem

Bleeding is the most common and potentially the most serious side effect of Lovenox. If prolonged or frequent bleeding, prolonged nosebleeds, gum bleeding, heavy menstrual bleeding, unexplained vaginal bleeding, or frequent bruising are experienced, these may be signs of a more serious problem with Lovenox. Contact a healthcare provider for advice. Any severe or overly prolonged bleeding episode should be treated in an emergency room.

7. Know the symptoms of internal bleeding

Bleeding can occur anywhere on or inside the body. Internal bleeding is particularly hazardous because it can’t be seen. Anyone taking Lovenox or caring for a person taking Lovenox should know the major symptoms of internal bleeding:

• Coughing up blood
• Vomiting blood or having blood clots in vomit (“coffee grounds” vomit)
• Pink, red, or brown urine
• Bright red or black, tarry stools
• Severe headache
• Dizziness
• Passing out
• Weakness, particularly if it affects only one part of the body
• Numbness
• Changes in vision
• Severe abdominal pain
• Shortness of breath
• A drop in blood pressure

Talk to a medical professional or get emergency medical help if any of these symptoms are experienced while taking Lovenox.

Related resources for Lovenox side effects:

• Anticoagulant safety, StatPearls
• Enoxaparin, Drugs and Lactation Database
• Enoxaparin, StatPearls
• Enoxaparin drug summary, Epocrates
• Lovenox, Epocrates
• Lovenox prescribing information, U.S. National Library of Medicine