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Low-molecular-weight heparin

Pooled trials found low-molecular-weight heparin under the skin led to fewer repeat clots and less major bleeding than unfractionated heparin, and fewer clots than placebo in hospital patients or warfarin-type drugs in cancer. Trials in recurrent miscarriage found no gain in live births. Major bleeding rose against no treatment. Heparin-induced thrombocytopenia was about ten times rarer than with unfractionated heparin.

Add to Bio HackChecked 2026-11-14
Status
Prescription drugs in the US, injected under the skin (enoxaparin can also be given into a vein). Lovenox (enoxaparin) is FDA-approved to prevent deep vein thrombosis after abdominal, hip or knee replacement surgery and in medical patients with severely restricted mobility, to treat deep vein thrombosis with or without pulmonary embolism, and in unstable angina and heart attack. Fragmin (dalteparin) is approved for unstable angina, for clot prevention after abdominal or hip surgery and in immobile medical patients, for extended treatment of venous clots in adults with cancer, and for venous clots in children from birth. Both carry an FDA boxed warning for spinal or epidural hematoma. Unfractionated heparin is a separate prescription injection, given into a vein or under the skin.
Also called
LMWH, enoxaparin, Lovenox, enoxaparin sodium, dalteparin, Fragmin, heparin, unfractionated heparin, UFH, heparin sodium, blood thinner injection, anticoagulant injection
Taken for
preventing blood clots, deep vein thrombosis, pulmonary embolism, clots after surgery, clots in hospital, cancer-associated clots, clots in pregnancy, recurrent miscarriage, IVF, bridging before surgery, COVID-19

Strong several reviews agree · Moderate one review or consistent trials · Limited one or a few small studies · Untested no study in people, listed with what it rests on

Shown to help5

Reported risks9

What people take it for, and what was found

Shown to help5

Moderate

Treating deep vein thrombosis and pulmonary embolism

Shown to lower repeat clots and major bleeding by about 30% against adjusted-dose unfractionated heparin when starting treatment for venous clots, with no difference in deaths.

Compared with adjusted-dose unfractionated heparin into a vein or under the skin [1]

The numbers and sources
Effect
Fixed-dose low-molecular-weight heparin under the skin lowered repeat venous clots during initial treatment (Peto OR 0.69, 95% CI 0.49 to 0.98, 18 studies), at 3 months (Peto OR 0.71) and at the end of follow-up (Peto OR 0.72, 95% CI 0.59 to 0.88, 22 studies). Clots shrank more (Peto OR 0.71). Major bleeding was less common (Peto OR 0.69, 95% CI 0.50 to 0.95, 25 studies). Overall mortality did not differ (Peto OR 0.84, 95% CI 0.70 to 1.01) [1].
Population
29 RCTs with 10,390 people with acute deep vein thrombosis or pulmonary embolism [1].
Sources
[1]
Caveats
Moderate-quality evidence, with poorly reported randomization in several trials. Clot size results were low quality with moderate heterogeneity [1].
Moderate

Preventing clots in hospital medical patients

Shown to lower deep vein thrombosis about 60% against placebo in acutely ill medical patients, with more major bleeding. Low-molecular-weight heparin had fewer clots and bleeds than unfractionated heparin.

Compared with placebo or no treatment [2]; unfractionated heparin under the skin [2]

The numbers and sources
Effect
Heparin lowered the odds of deep vein thrombosis against placebo or no treatment (OR 0.38, 95% CI 0.29 to 0.51). Drops in nonfatal and fatal pulmonary embolism were imprecise (combined OR 0.65, 95% CI 0.42 to 1.00). Major bleeding rose (OR 1.81, 95% CI 1.10 to 2.98), and all-cause mortality showed no clear change. Against unfractionated heparin, low-molecular-weight heparin lowered deep vein thrombosis (OR 0.77, 95% CI 0.62 to 0.96) and major bleeding (OR 0.43, 95% CI 0.22 to 0.83) [2].
Population
16 RCTs with 34,369 acutely ill medical inpatients, excluding heart attack, stroke and intensive care [2].
Sources
[2]
Caveats
Nearly half the trials were open-label, and randomization was poorly described [2]. Much of the reduction is in clots found by screening, not symptoms.
Moderate

Preventing clots after surgery and injury

Shown to lower clinical pulmonary embolism about 75% against placebo after general surgery, and deep vein thrombosis about a third against unfractionated heparin after injury.

Compared with placebo or no treatment [3]; unfractionated heparin under the skin [3][4]

The numbers and sources
Effect
After general surgery, low-molecular-weight heparin lowered clinical pulmonary embolism (RR 0.25, 95% CI 0.08 to 0.79) and clinical venous clots (RR 0.29, 95% CI 0.11 to 0.73) against placebo or no treatment. Against unfractionated heparin it lowered clinical venous clots slightly (P = 0.049). Doses above 3,400 anti-Xa units raised bleeding, including major bleeding [3]. In trauma patients, 4 RCTs found less deep vein thrombosis (RR 0.67, 95% CI 0.50 to 0.88) and fewer venous clots (RR 0.68, 95% CI 0.51 to 0.90) than with unfractionated heparin, moderate certainty [4].
Population
General surgery trials, up to 5,456 patients per outcome [3]; 879 trauma patients in 4 RCTs and 306,747 in 8 observational studies [4].
Sources
[3], [4]
Caveats
The surgery review is from 2001 [3]. Lower pulmonary embolism and death against unfractionated heparin in trauma came only from observational studies, low certainty [4].
Moderate

Treating clots in people with cancer

Shown to lower repeat clots about 42% against warfarin-type drugs in people with cancer, with no difference in deaths or major bleeding.

Compared with vitamin K antagonists such as warfarin [5][6]; direct oral anticoagulants [5]

The numbers and sources
Effect
Against vitamin K antagonists, low-molecular-weight heparin lowered repeat venous clots (RR 0.58, 95% CI 0.43 to 0.77, 53 fewer per 1,000), with no clear difference in deaths at 12 months (RR 1.00), major bleeding (RR 1.09, 95% CI 0.55 to 2.12) or low platelets. Against direct oral anticoagulants, repeat clots were slightly more common on low-molecular-weight heparin (DOAC RR 0.69, 95% CI 0.47 to 1.01) and major bleeding less common (DOAC RR 1.71, 95% CI 1.01 to 2.88), both low certainty [5]. In the CLOT trial, 9% on dalteparin and 17% on an oral anticoagulant had a repeat clot by 6 months (HR 0.48). Major bleeding was 6% and 4%, and mortality 39% and 41% [6].
Population
16 RCTs with 5,167 people with cancer and venous clots [5]; 672 people with cancer and acute clots [6].
Sources
[5], [6]
Caveats
CLOT is one of the trials pooled in [5]. The DOAC comparison rests on one published trial [5]. The 6-month course in CLOT is the basis of Fragmin's cancer indication [7].
Moderate

Preventing clots in people with cancer on chemotherapy

Shown to lower symptomatic venous clots about 38% against no prevention in outpatients on chemotherapy, with about 63% more major bleeding.

Compared with no thromboprophylaxis or placebo [8]; warfarin and aspirin in multiple myeloma [8]

The numbers and sources
Effect
Low-molecular-weight heparin lowered symptomatic venous clots against no thromboprophylaxis (RR 0.62, 95% CI 0.46 to 0.83, 11 studies, 3,931 participants, high certainty) and probably raised major bleeding (RR 1.63, 95% CI 1.12 to 2.35, 15 studies, 7,282 participants). In multiple myeloma it lowered symptomatic clots against warfarin (RR 0.33, 95% CI 0.14 to 0.83) and probably against aspirin (RR 0.51, 95% CI 0.22 to 1.17) [8].
Population
32 RCTs with 15,678 ambulatory people with cancer on chemotherapy, mostly locally advanced or metastatic [8].
Sources
[8]
Caveats
One review. The absolute clot rate without prevention varies by cancer type.

Mixed results3

Limited

COVID-19 in hospital

Mixed results: full-dose heparin raised survival without organ support against usual preventive doses in patients not critically ill, and did not in critically ill patients.

Compared with usual-care preventive-dose anticoagulation [11][12]

The numbers and sources
Effect
In patients not critically ill, therapeutic-dose heparin raised organ support-free days (adjusted OR 1.27, 95% credible interval 1.03 to 1.58), and survival to discharge without organ support by 4.0 percentage points. Major bleeding was 1.9% against 0.9% [11]. In critically ill patients, the trial stopped for futility. Survival to discharge was 62.7% against 64.5% (adjusted OR 0.84), and major bleeding 3.8% against 2.3% [12].
Population
2,219 patients not critically ill [11]; 1,098 critically ill patients [12].
Sources
[11], [12]
Caveats
Open-label adaptive platform trials using heparin regimens chosen locally, low-molecular-weight or unfractionated [11][12].
LimitedStudied in pregnancy

Preventing clots in pregnancy and after birth

Limited evidence: trials of heparin against no treatment in pregnancy and after cesarean birth were too small to show whether clots fell, with very low certainty.

Compared with no treatment or placebo [13]; unfractionated heparin [13]

The numbers and sources
Effect
During pregnancy, symptomatic clots did not clearly differ with heparin against no treatment or placebo (RR 0.39, 95% CI 0.08 to 1.98, 4 trials, 476 women) or with low-molecular-weight against unfractionated heparin (RR 0.47, 95% CI 0.09 to 2.49). After cesarean birth, symptomatic clots did not clearly differ against no treatment or placebo (RR 1.30, 95% CI 0.39 to 4.27, 4 trials, 840 women). Stopping for side effects was less common on low-molecular-weight than unfractionated heparin (RR 0.07, 95% CI 0.01 to 0.54, 2 trials, 226 women) [13].
Population
29 trials with 3,839 women at raised risk of clots in pregnancy or after birth [13].
Sources
[13]
Caveats
All critical outcomes were very low certainty, with few events [13].
LimitedStudied in women

Live births with IVF

Limited evidence: three small trials found more live births with heparin around embryo transfer, and the result disappeared under a different statistical model.

Compared with placebo or no heparin [16]

The numbers and sources
Effect
Low-molecular-weight heparin around implantation raised live births (OR 1.77, 95% CI 1.07 to 2.90) and clinical pregnancy (OR 1.61) against placebo or no heparin, very low quality evidence. Neither was significant with a random-effects model. Bruising, bleeding, low platelets and allergic reactions were reported [16].
Population
386 women in 3 RCTs having assisted reproduction [16].
Sources
[16]
Caveats
Small trials, high heterogeneity, and poorly reported harms [16].

Not shown to help4

Moderate

Preventing clots after knee arthroscopy or a lower-leg cast

Not shown to lower symptomatic venous clots against no anticoagulant after knee arthroscopy or during lower-leg casting.

Compared with no anticoagulant [9]

The numbers and sources
Effect
After knee arthroscopy, venous clots occurred in 0.7% on a preventive dose of low-molecular-weight heparin for 8 days and 0.4% with none (RR 1.6, 95% CI 0.4 to 6.8). During lower-leg casting they occurred in 1.4% and 1.8% (RR 0.8, 95% CI 0.3 to 1.7). Major bleeding was 0.1% in each arthroscopy group, with none in the casting trial [9].
Population
1,451 adults after knee arthroscopy and 1,435 with a lower-leg cast, in two Dutch trials, followed 3 months [9].
Sources
[9]
Caveats
Open-label with blinded outcome assessment [9].
Limited

Bridging around surgery in atrial fibrillation

One trial found no fewer strokes or emboli with dalteparin bridging than with placebo injections while warfarin was paused, and more than twice the major bleeding.

Compared with placebo injections under the skin [10]

The numbers and sources
Effect
Arterial thromboembolism (stroke, systemic embolism or transient ischemic attack) occurred in 0.3% with dalteparin 100 IU/kg under the skin twice daily and 0.4% with placebo. Major bleeding occurred in 3.2% and 1.3% (RR for no bridging 0.41, 95% CI 0.20 to 0.78) [10].
Population
1,884 people with atrial fibrillation on warfarin having an elective procedure, followed 30 days [10].
Sources
[10]
Caveats
Few people with mechanical heart valves or recent stroke were in the trial. Double-blind [10].
Why limited
This rests on one trial, of 1,884 people. Strength counts independent studies that agree, so one trial is limited at any size.
LimitedStudied in pregnancy

Recurrent miscarriage with inherited thrombophilia

One trial found live births were not higher with low-dose low-molecular-weight heparin, 72% against 71%, in women with recurrent miscarriage and inherited thrombophilia.

Compared with standard care with no heparin [14]

The numbers and sources
Effect
Live births occurred in 116 of 162 women (72%) on low-molecular-weight heparin under the skin from 7 weeks to the end of pregnancy and 112 of 158 (71%) on standard care (adjusted OR 1.08, 95% CI 0.65 to 1.78). Adverse events were reported by 24% and 23% [14].
Population
326 pregnant women aged 18 to 42 with two or more pregnancy losses and confirmed inherited thrombophilia, in five countries [14].
Sources
[14]
Caveats
Open-label, and smaller than the number of women screened suggests [14].
ModerateStudied in pregnancy

Preventing recurrent pre-eclampsia and other placental complications

Not shown to lower recurrent placental complications, 14% against 22%, in pregnant women with a past complication, in a pooled analysis of patient data.

Compared with no low-molecular-weight heparin [15]

The numbers and sources
Effect
Pre-eclampsia, placental abruption, a small-for-gestational-age baby or late pregnancy loss recurred in 14% on low-molecular-weight heparin and 22% without it (RR 0.64, 95% CI 0.36 to 1.11). Results differed between single-center and multicenter trials. In multicenter trials it lowered recurrence in women with a past abruption [15].
Population
Individual data on 963 pregnant women in 8 RCTs, 42% with thrombophilia [15].
Sources
[15]
Caveats
The study may have lacked power for small effects [15].

Doses studied

Lovenox's label gives 40 mg under the skin once daily for clot prevention after abdominal surgery and in immobile medical patients, and 30 mg every 12 hours after hip or knee replacement, and 1 mg/kg every 12 hours or 1.5 mg/kg once daily for treating deep vein thrombosis. The label's surgery trials compared 40 mg daily with unfractionated heparin 5,000 units every 8 hours under the skin [17]. Fragmin's label for clots in cancer gives 200 units/kg under the skin once daily for the first 30 days, then about 150 units/kg once daily in months 2 to 6, with a daily maximum of 18,000 units [7]. BRIDGE gave dalteparin 100 IU/kg under the skin twice daily [10]. The arthroscopy and cast trials used one preventive dose a day, for 8 days after arthroscopy or for the whole time in the cast [9]. ALIFE2 used low-dose low-molecular-weight heparin from 7 weeks of pregnancy to delivery [14].

Risks

Reported risks9

LimitedStudied in pregnancyVery common

Bleeding and birth defects in pregnancy

In records of 604 pregnant women on enoxaparin, 63 had bleeding events, 11 serious, and major birth defects were at background rates.

The numbers and sources
How common
Very common: more than 1 in 10 people.
Effect
A retrospective review of 624 pregnancies in 604 women on Lovenox found 72 bleeding events (11 serious) in 63 women and 14 bleeds in newborns. Major congenital anomalies occurred in 2.5% of 693 live births, similar to background rates. The label warns hemorrhage may lead to death of mother or fetus, and advises preservative-free forms in pregnancy because benzyl alcohol may cross the placenta [17].
Population
604 pregnant women and 693 live births [17].
Sources
[17]
Caveats
No comparison group, so the bleeding rate cannot be attributed to the drug alone [17].
StrongCommon

Major bleeding against no treatment

Shown to raise major bleeding about 1.6 to 2.5 times against placebo or no treatment, to about 2 to 3% in trials of hospital, cancer and surgery patients.

The numbers and sources
How common
Common: between 1 in 100 and 1 in 10 people.
Effect
In acutely ill medical patients, major bleeding rose against placebo or no treatment (OR 1.81, 95% CI 1.10 to 2.98) [2]. In outpatients with cancer on chemotherapy it rose against no thromboprophylaxis (RR 1.63, 95% CI 1.12 to 2.35) [8]. Bridging with dalteparin gave major bleeding in 3.2% against 1.3% on placebo injections [10]. Full-dose heparin for COVID-19 gave 1.9% against 0.9% on preventive doses [11]. The Lovenox label reports major bleeding in 4% on enoxaparin 40 mg daily and 3% on unfractionated heparin after abdominal or colorectal surgery [17].
Population
34,369 medical inpatients [2]; 7,282 people with cancer [8]; 1,884 people with atrial fibrillation [10]; 2,219 COVID-19 patients [11]; 2,462 surgery patients [17].
Sources
[2], [8], [10], [11], [17]
Caveats
Bleeding definitions varied between trials. The label states some major bleeds, including retroperitoneal and brain bleeds, were fatal [17].
ModerateCommon

Low platelet count

Shown to lower platelets moderately in 1.3% on enoxaparin, against 1.2% on unfractionated heparin and 0.7% on placebo.

The numbers and sources
How common
Common: between 1 in 100 and 1 in 10 people.
Effect
Platelets of 50,000 to 100,000 per mm3 occurred in 1.3% on Lovenox, 1.2% on heparin and 0.7% on placebo. Counts below 50,000 occurred in 0.1%, 0.2% and 0.4% [17].
Population
Patients in the Lovenox clinical trials [17].
Sources
[17]
Caveats
Label pooled data. The label sets stopping when platelets fall below 100,000 per mm3 [17].
StrongUncommon

Heparin-induced thrombocytopenia

Shown to cause heparin-induced thrombocytopenia in about 0.2% on low-molecular-weight heparin against 2.6% on unfractionated heparin, mostly after surgery. The label warns it can cause clots and death.

The numbers and sources
How common
Uncommon: between 1 in 1,000 and 1 in 100 people.
Effect
Pooled absolute risk was 0.2% with low-molecular-weight heparin and 2.6% with unfractionated heparin (RCTs OR 0.10, 95% CI 0.01 to 0.2) [18]. After surgery, risk was lower with low-molecular-weight heparin (RR 0.23, 95% CI 0.07 to 0.73, number needed to treat 59), as was heparin-induced thrombocytopenia with venous clots (RR 0.22). With either heparin it occurred in 1% to 10% of people after major surgery [19]. The Lovenox label warns it may lead to organ infarction, limb ischemia or death, and bars use within 100 days of a past episode [17].
Population
7,287 patients in 15 studies, mostly after orthopedic surgery [18]; 1,398 postoperative patients in 3 RCTs [19].
Sources
[18], [19], [17]
Caveats
Low-quality evidence [19]. Most data are from preventive doses.
LimitedHow often is not known

FDA boxed warning: spinal or epidural hematoma

FDA states that bleeding around the spinal cord can occur with these drugs during spinal or epidural anesthesia or spinal puncture, and can cause long-term or permanent paralysis.

The numbers and sources
How common
How often is not known: the sources give no rate.
Effect
The Lovenox and Fragmin labels carry a boxed warning that epidural or spinal hematomas may occur in people on low-molecular-weight heparin who receive neuraxial anesthesia or a spinal puncture. Named risk factors are indwelling epidural catheters, NSAIDs, platelet inhibitors and other anticoagulants, traumatic or repeated punctures, and past spinal surgery or deformity. Most reported cases after approval involved an indwelling epidural catheter or other drugs affecting clotting [17][7].
Population
Reports after approval in people given low-molecular-weight heparin with spinal or epidural procedures [17][7].
Sources
[17], [7]
Caveats
The labels give no rate. The Lovenox label sets delays of at least 12 hours after lower doses and 24 hours after higher doses before placing or removing a catheter [17].
ModerateHow often is not known

Raised liver enzymes

The label reports ALT and AST rises above three times normal, without symptoms, in up to about 6% of patients on enoxaparin.

The numbers and sources
How common
How often is not known: the sources give no rate.
Effect
Asymptomatic rises in AST and ALT above three times the upper limit of normal were reported in up to 6.1% and 5.9% of patients during Lovenox treatment. Liver injury cases were reported after approval [17].
Population
Patients in the Lovenox clinical trials and reports after approval [17].
Sources
[17]
Caveats
The label gives no placebo rate for this [17].
LimitedStudied in pregnancyHow often is not known

Valve clots in pregnant women with mechanical heart valves

The label warns that enoxaparin in pregnant women with mechanical heart valves may lead to valve clots. In one small study, 2 of 8 women died with blocked valves.

The numbers and sources
How common
How often is not known: the sources give no rate.
Effect
In a study of pregnant women with mechanical valves given enoxaparin 1 mg/kg twice daily, 2 of 8 developed valve-blocking clots leading to maternal and fetal death, against 0 of 4 on heparin and warfarin. Isolated reports after approval describe the same [17].
Population
12 pregnant women with mechanical heart valves [17].
Sources
[17]
Caveats
Too few women for a rate [17].
LimitedHow often is not known

High potassium, bone loss and skin reactions reported after approval

Case reports: high potassium, mostly in people with kidney problems or on potassium-sparing drugs, bone loss with long use, and skin death at or away from the injection site.

The numbers and sources
How common
How often is not known: the sources give no rate.
Effect
The Lovenox label lists reports of hyperkalemia, most in people with kidney dysfunction, potassium-sparing drugs, potassium supplements or tissue bleeding. It also lists osteoporosis after long-term therapy, skin necrosis, allergic reactions including anaphylaxis, hair loss and liver injury [17].
Population
Voluntary reports after approval [17].
Sources
[17]
Caveats
The label states the size of the reporting population is unknown and causation is not established [17].
LimitedHow often is not known

Interactions with other blood thinners and NSAIDs

The label warns that anticoagulants, aspirin and other platelet inhibitors, and NSAIDs including ketorolac raise bleeding risk with enoxaparin.

The numbers and sources
How common
How often is not known: the sources give no rate.
Effect
The Lovenox label names anticoagulants, platelet inhibitors including aspirin and salicylates, NSAIDs including ketorolac, dipyridamole and sulfinpyrazone as agents that may raise the risk of bleeding, and names NSAIDs and platelet inhibitors as risk factors for spinal hematoma [17]. The Fragmin label carries the same boxed warning [7].
Population
Label statements [17][7].
Sources
[17], [7]
Caveats
A label statement, not a measured rate.

Checked, no increase found1

Strong

Major bleeding against unfractionated heparin

Major bleeding was about 30 to 57% less common on low-molecular-weight heparin than on unfractionated heparin, in treating clots and preventing them in medical patients.

The numbers and sources
How common
How often is not known: the sources give no rate.
Effect
When starting treatment for venous clots, major bleeding was less common on fixed-dose low-molecular-weight heparin than on adjusted-dose unfractionated heparin (Peto OR 0.69, 95% CI 0.50 to 0.95, 25 studies, 8,780 participants) [1]. For prevention in medical inpatients, major bleeding was less common than on unfractionated heparin (OR 0.43, 95% CI 0.22 to 0.83) [2]. In trauma, adverse events did not clearly differ (RR 0.80, very low certainty) [4].
Population
8,780 people treated for venous clots [1]; medical inpatients in 6 head-to-head trials [2]; 879 trauma patients [4].
Sources
[1], [2], [4]
Caveats
Moderate-quality evidence [1].

Claims tested and not found

  1. That heparin raises live births in recurrent miscarriage with inherited thrombophilia. Live births were 72% on low-molecular-weight heparin and 71% on standard care [14].
  2. That heparin prevents recurrent pre-eclampsia and other placental complications. Recurrence did not differ significantly in pooled patient data (RR 0.64, 95% CI 0.36 to 1.11) [15].
  3. That injections are needed after knee arthroscopy or in a lower-leg cast. Symptomatic clots did not differ from no anticoagulant in either trial [9].
  4. That bridging injections prevent strokes when warfarin is paused for surgery in atrial fibrillation. Arterial clots were 0.3% with dalteparin and 0.4% with placebo [10].
  5. That full-dose heparin helps critically ill COVID-19 patients. The trial stopped for futility, with survival 62.7% against 64.5% [12].

Related

WarfarinDirect oral anticoagulants (DOACs)

Sources

  1. Robertson L, Jones LE. Fixed dose subcutaneous low molecular weight heparins versus adjusted dose unfractionated heparin for the initial treatment of venous thromboembolism. Cochrane Database of Systematic Reviews. 2017. https://doi.org/10.1002/14651858.cd001100.pub4
  2. Alikhan R, Forster R, Cohen AT. Heparin for the prevention of venous thromboembolism in acutely ill medical patients (excluding stroke and myocardial infarction). Cochrane Database of Systematic Reviews. 2014. https://doi.org/10.1002/14651858.cd003747.pub4
  3. Mismetti P, Laporte S, Darmon J, Buchmüller A, Decousus H. Meta-analysis of low molecular weight heparin in the prevention of venous thromboembolism in general surgery. British Journal of Surgery. 2001. https://doi.org/10.1046/j.0007-1323.2001.01800.x
  4. Tran A, Fernando SM, Carrier M, et al. Efficacy and Safety of Low Molecular Weight Heparin Versus Unfractionated Heparin for Prevention of Venous Thromboembolism in Trauma Patients: A Systematic Review and Meta-analysis. Annals of Surgery. 2022. https://doi.org/10.1097/sla.0000000000005157
  5. Kahale LA, Hakoum MB, Tsolakian IG, et al. Anticoagulation for the long-term treatment of venous thromboembolism in people with cancer. Cochrane Database of Systematic Reviews. 2018. https://doi.org/10.1002/14651858.cd006650.pub5
  6. Lee AY, Levine MN, Baker RI, et al. Low-Molecular-Weight Heparin versus a Coumarin for the Prevention of Recurrent Venous Thromboembolism in Patients with Cancer. New England Journal of Medicine. 2003. https://doi.org/10.1056/nejmoa025313
  7. US Food and Drug Administration. Fragmin (dalteparin sodium injection) prescribing information, revised October 2025. DailyMed. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=23527b8b-9b28-4e6d-9751-33b143975ac7
  8. Rutjes AW, Porreca E, Candeloro M, Valeriani E, Di Nisio M. Primary prophylaxis for venous thromboembolism in ambulatory cancer patients receiving chemotherapy. Cochrane Database of Systematic Reviews. 2020. https://doi.org/10.1002/14651858.cd008500.pub5
  9. van Adrichem RA, Nemeth B, Algra A, et al. Thromboprophylaxis after Knee Arthroscopy and Lower-Leg Casting. New England Journal of Medicine. 2017. https://doi.org/10.1056/nejmoa1613303
  10. Douketis JD, Spyropoulos AC, Kaatz S, et al. Perioperative Bridging Anticoagulation in Patients with Atrial Fibrillation. New England Journal of Medicine. 2015. https://doi.org/10.1056/nejmoa1501035
  11. ATTACC, ACTIV-4a, and REMAP-CAP Investigators. Therapeutic Anticoagulation with Heparin in Noncritically Ill Patients with Covid-19. New England Journal of Medicine. 2021. https://doi.org/10.1056/nejmoa2105911
  12. REMAP-CAP, ACTIV-4a, and ATTACC Investigators. Therapeutic Anticoagulation with Heparin in Critically Ill Patients with Covid-19. New England Journal of Medicine. 2021. https://doi.org/10.1056/nejmoa2103417
  13. Middleton P, Shepherd E, Gomersall JC. Venous thromboembolism prophylaxis for women at risk during pregnancy and the early postnatal period. Cochrane Database of Systematic Reviews. 2021. https://doi.org/10.1002/14651858.cd001689.pub4
  14. Quenby S, Booth K, Hiller L, et al. Heparin for women with recurrent miscarriage and inherited thrombophilia (ALIFE2): an international open-label, randomised controlled trial. The Lancet. 2023. https://doi.org/10.1016/s0140-6736(23)00693-1
  15. Rodger MA, Gris JC, de Vries JIP, et al. Low-molecular-weight heparin and recurrent placenta-mediated pregnancy complications: a meta-analysis of individual patient data from randomised controlled trials. The Lancet. 2016. https://doi.org/10.1016/s0140-6736(16)31139-4
  16. Akhtar MA, Sur SD, Raine-Fenning N, Jayaprakasan K, Thornton JG, Quenby S. Heparin for assisted reproduction. Cochrane Database of Systematic Reviews. 2013. https://doi.org/10.1002/14651858.cd009452.pub2
  17. US Food and Drug Administration. Lovenox (enoxaparin sodium injection) prescribing information, revised May 2026. DailyMed. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=5017a927-2a24-4f27-89f9-27c805bf7d59
  18. Martel N, Lee J, Wells PS. Risk for heparin-induced thrombocytopenia with unfractionated and low-molecular-weight heparin thromboprophylaxis: a meta-analysis. Blood. 2005. https://doi.org/10.1182/blood-2005-04-1546
  19. Junqueira DR, Zorzela LM, Perini E. Unfractionated heparin versus low molecular weight heparins for avoiding heparin-induced thrombocytopenia in postoperative patients. Cochrane Database of Systematic Reviews. 2017. https://doi.org/10.1002/14651858.cd007557.pub3

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