Fragmin (Dalteparin)
Low Molecular Weight Heparin for Blood Clot Prevention and Treatment
Quick Facts About Fragmin
Key Takeaways About Fragmin
- Effective blood clot prevention: Fragmin significantly reduces the risk of deep vein thrombosis and pulmonary embolism in surgical patients, medically ill patients, and cancer patients
- Subcutaneous injection: Administered as a daily or twice-daily injection under the skin, which patients can learn to self-inject at home after initial training
- Cancer-associated thrombosis: Fragmin is one of the preferred anticoagulants for long-term treatment and prevention of blood clots in cancer patients, as supported by the CLOT trial
- Monitor for bleeding: The most important risk is bleeding, which is dose-dependent. Report any unusual bruising, blood in urine or stool, or prolonged bleeding from cuts to your doctor immediately
- Benzyl alcohol warning: Multi-dose vials contain benzyl alcohol as a preservative, which must be avoided in neonates, young children under 3 years, and pregnant or breastfeeding women. Preservative-free formulations are available
What Is Fragmin and What Is It Used For?
Fragmin (dalteparin sodium) is an antithrombotic medication belonging to the low molecular weight heparin (LMWH) class. It is used to prevent and treat blood clots (thrombi) in the deep veins and lungs, prevent clotting during kidney dialysis, and treat unstable coronary artery disease. Fragmin works by enhancing the activity of antithrombin III, a natural protein in the blood that inhibits clot formation.
Dalteparin is derived from porcine (pig) intestinal mucosa heparin through a controlled depolymerisation process, resulting in heparin fragments with a mean molecular weight of approximately 6,000 daltons. This smaller molecular weight, compared to unfractionated heparin (12,000–15,000 daltons), gives dalteparin several pharmacological advantages: more predictable anticoagulant response, higher bioavailability after subcutaneous injection, longer half-life permitting once- or twice-daily dosing, and a lower incidence of heparin-induced thrombocytopenia (HIT).
Fragmin is approved for use in adults aged 18 years and older for a range of clinical indications. In deep vein thrombosis (DVT) and pulmonary embolism (PE), Fragmin serves as both initial treatment and ongoing therapy. Deep vein thrombosis occurs when blood clots form in the deep veins of the legs, while pulmonary embolism is a potentially life-threatening condition in which a blood clot travels to the lungs. The European Society of Cardiology (ESC) and the American College of Chest Physicians (ACCP) recognise low molecular weight heparins as first-line treatment for acute venous thromboembolism.
For cancer patients, Fragmin holds a particularly important role. The landmark CLOT trial (Comparison of Low-Molecular-Weight Heparin versus Oral Anticoagulant Therapy for the Prevention of Recurrent Venous Thromboembolism in Patients with Cancer) demonstrated that dalteparin reduced the recurrence of venous thromboembolism by approximately 50% compared to warfarin in cancer patients. International guidelines, including those from the International Society on Thrombosis and Haemostasis (ISTH), recommend LMWH as a preferred option for cancer-associated thrombosis treatment for at least 6 months.
Fragmin is also used perioperatively to prevent blood clots in patients undergoing surgical procedures, particularly orthopaedic, abdominal, and oncological surgery. Patients who are temporarily immobilised due to acute medical illness such as heart failure, severe respiratory disease, or serious infections also benefit from prophylactic Fragmin treatment. Additionally, Fragmin is used to prevent clotting in the extracorporeal circuit during haemodialysis and haemofiltration in patients with renal impairment.
In unstable coronary artery disease (unstable angina and non-ST-elevation myocardial infarction), Fragmin is administered alongside aspirin as part of acute coronary syndrome management. It helps prevent the progression of partially occluding thrombi in coronary arteries, reducing the risk of heart attack and death.
Fragmin is also approved for the treatment of venous thromboembolism in children aged 1 month and older. Paediatric dosing is weight- and age-based, with anti-Xa level monitoring used to guide dose adjustments.
Fragmin was first approved for medical use in 1988 and is manufactured by Pfizer. It is listed on the World Health Organization's Model List of Essential Medicines as a low molecular weight heparin, recognising its importance in global healthcare. Dalteparin was one of the first LMWHs to be developed and remains one of the most extensively studied anticoagulants, with decades of clinical evidence supporting its safety and efficacy.
What Should You Know Before Taking Fragmin?
Before starting Fragmin, inform your doctor about all your medical conditions, especially any history of bleeding disorders, low platelet count, peptic ulcer disease, liver or kidney impairment, and any other medications you are taking. Fragmin is contraindicated in patients with active bleeding, heparin-induced thrombocytopenia, and bacterial endocarditis.
Contraindications
You should not use Fragmin if any of the following apply to you:
- Allergy to dalteparin, heparin, or any other ingredient in the product – allergic reactions can range from skin rashes to severe anaphylaxis
- Thrombocytopenia (low platelet count) – particularly heparin-induced thrombocytopenia (HIT), a serious immune-mediated condition where heparin paradoxically causes blood clots. Your doctor will have informed you if you have this condition
- Active peptic ulcer disease – gastric or duodenal ulcers with active or recent bleeding
- Cerebral haemorrhage or other active bleeding – any current uncontrolled bleeding from any site
- Increased tendency to bleed – conditions such as haemophilia, von Willebrand disease, or severe coagulation factor deficiencies
- Bacterial endocarditis – infection of the heart valves, which creates friable vegetations prone to embolisation
- Recent injury or surgery of the central nervous system, eyes, or ears – increased risk of catastrophic haemorrhage in these areas
Spinal or epidural anaesthesia must be avoided when Fragmin is being used at treatment doses for acute deep vein thrombosis, pulmonary embolism, or unstable coronary artery disease. The combination carries a risk of spinal or epidural haematoma, which can lead to permanent paralysis. If you are scheduled for any procedure involving spinal anaesthesia, inform your anaesthetist that you are receiving Fragmin.
Warnings and Precautions
Tell your doctor or pharmacist before using Fragmin if you have or have had any of the following conditions, as they may affect how Fragmin works or require closer monitoring:
- Thrombocytopenia or platelet function disorders – your platelet count should be monitored before and regularly during treatment
- Severely impaired liver function – reduced synthesis of clotting factors increases bleeding risk
- Severely impaired kidney function – dalteparin is primarily eliminated by the kidneys, and reduced clearance may lead to drug accumulation. Anti-Xa monitoring may be required
- Uncontrolled high blood pressure – hypertension increases the risk of bleeding, particularly cerebral haemorrhage
- Diabetic or hypertensive retinopathy – changes in the retinal blood vessels increase the risk of ocular haemorrhage
- Diabetes mellitus – Fragmin can increase potassium levels in the blood, and diabetic patients are at higher risk
- Elevated potassium levels (hyperkalaemia) – Fragmin can suppress aldosterone production, leading to potassium retention
- Recent heart attack – close monitoring is required to balance bleeding risk against the need for anticoagulation
- Elderly patients – there may be an increased risk of bleeding in older adults, particularly those with reduced kidney function
- Latex allergy – the needle shield on Fragmin pre-filled syringes may contain natural rubber latex, which can cause severe allergic reactions in latex-sensitive individuals
If you are about to undergo any surgical or dental procedure, it is essential to inform your surgeon, anaesthetist, or dentist that you are using Fragmin. The timing of your last injection and any required bridging strategy must be carefully planned to minimise both bleeding and clotting risks.
Use in Children
Fragmin is approved for the treatment of venous thromboembolism (VTE) in children and adolescents aged 1 month and older. It should not be used in neonates younger than 1 month of age. In paediatric patients, dosing is based on body weight and age, and anti-Xa levels are monitored to ensure appropriate anticoagulation.
Products containing benzyl alcohol (multi-dose vials) must not be used in neonates and should not be administered for more than one week in young children aged 1 month to 3 years unless specifically recommended by a doctor. Benzyl alcohol has been associated with severe adverse reactions including respiratory distress (“gasping syndrome”) in neonates. Preservative-free formulations (pre-filled syringes) should be used for paediatric patients whenever possible.
Pregnancy and Breastfeeding
Pregnancy: There are no known risks associated with using Fragmin during pregnancy, and it is considered one of the preferred anticoagulants for pregnant women requiring thromboprophylaxis or VTE treatment. Unlike warfarin, dalteparin does not cross the placenta and therefore does not pose a risk of foetal bleeding or teratogenicity. However, multi-dose vials containing benzyl alcohol must be avoided during pregnancy, as benzyl alcohol can cross the placenta. Preservative-free pre-filled syringes should be used instead.
Breastfeeding: Dalteparin is excreted in breast milk in very small amounts. Given the large molecular weight of the drug and its poor oral bioavailability, the amount absorbed by the nursing infant is expected to be negligible. Nevertheless, you should consult your doctor before using Fragmin while breastfeeding. As with pregnancy, products containing benzyl alcohol should be avoided during breastfeeding, and preservative-free formulations should be used instead.
Fertility: Clinical data do not suggest that Fragmin affects fertility in either men or women.
Driving and Operating Machinery
Fragmin does not affect the ability to drive or operate machinery. However, you should be aware of any symptoms of bleeding (such as dizziness or lightheadedness) that could impair your ability to perform these activities safely. If you experience such symptoms, do not drive until they have resolved and consult your doctor.
Benzyl Alcohol and Sodium Content
Certain Fragmin formulations (10,000 IU/ml in 10 ml vials and 25,000 IU/ml in 4 ml vials) contain benzyl alcohol as a preservative. Benzyl alcohol can cause allergic reactions and has been associated with serious adverse effects including respiratory distress in neonates. These formulations must not be given to neonates (under 4 weeks of age) and should not be used for more than 1 week in young children (under 3 years) unless specifically recommended by a doctor. Patients with impaired liver or kidney function, and pregnant or breastfeeding women, should also use preservative-free Fragmin formulations.
Pre-filled syringes of Fragmin are essentially “sodium-free” (containing less than 1 mmol/23 mg sodium per syringe). The multi-dose vials contain varying amounts of sodium: the 2,500 IU/ml vial (4 ml) contains 24.2 mg sodium per vial, while the 10,000 IU/ml (10 ml) and 25,000 IU/ml (4 ml) vials each contain 113.6 mg sodium. Patients on a sodium-restricted diet should be aware of this sodium content.
How Does Fragmin Interact with Other Drugs?
Fragmin can interact with several medications that affect blood clotting or increase the risk of bleeding. Always inform your doctor about all medications you are taking, including over-the-counter products, herbal supplements, and other prescription drugs. The risk of bleeding increases significantly when Fragmin is combined with other anticoagulants, antiplatelet agents, or non-steroidal anti-inflammatory drugs (NSAIDs).
Because dalteparin works by inhibiting the coagulation cascade, any medication that also affects haemostasis can amplify or diminish its effects. The following tables summarise the most clinically important drug interactions. Your doctor will weigh the risks and benefits carefully before prescribing any combination therapy.
Major Interactions
| Drug | Category | Effect | Recommendation |
|---|---|---|---|
| Warfarin | Oral anticoagulant (vitamin K antagonist) | Additive anticoagulant effect; significantly increased risk of major bleeding | Use with extreme caution; close INR monitoring required during overlap periods |
| Apixaban / Rivaroxaban / Edoxaban | Direct oral anticoagulants (DOACs) | Additive anticoagulant effect; high risk of major and fatal bleeding | Do not combine; ensure adequate washout period when switching between agents |
| Glycoprotein IIb/IIIa inhibitors (abciximab, eptifibatide, tirofiban) | Antiplatelet agents | Markedly increased bleeding risk due to combined anticoagulant and antiplatelet effects | Use only in specialised settings with close monitoring (e.g., cardiac catheterisation labs) |
| Andexanet alfa | Factor Xa inhibitor reversal agent | May reduce the anticoagulant effect of dalteparin by reversing factor Xa inhibition | Be aware of potential reduced Fragmin efficacy if andexanet alfa has been recently administered |
Moderate Interactions
| Drug | Category | Effect | Recommendation |
|---|---|---|---|
| Aspirin (Acetylsalicylic acid) | Antiplatelet / NSAID | Increased bleeding risk due to antiplatelet action and gastric mucosal damage | May be combined for unstable coronary artery disease under medical supervision; otherwise avoid |
| Clopidogrel / Prasugrel / Ticagrelor | Antiplatelet agents (P2Y12 inhibitors) | Additive risk of bleeding from combined antiplatelet and anticoagulant effects | Use combination with caution; closely monitor for signs of bleeding |
| NSAIDs (ibuprofen, diclofenac, naproxen) | Non-steroidal anti-inflammatory drugs | Increased bleeding risk, especially gastrointestinal bleeding; NSAIDs also impair platelet function | Avoid concurrent use if possible; use paracetamol (acetaminophen) as an alternative analgesic |
| Dextran | Plasma volume expander | Additive effect on coagulation; dextran impairs platelet function and fibrin polymerisation | Avoid combination; use alternative plasma expanders when possible |
| Systemic corticosteroids | Anti-inflammatory / immunosuppressant | Increased risk of gastrointestinal bleeding | Monitor for signs of GI bleeding; consider gastroprotection if combination is necessary |
If you are being treated for unstable coronary artery disease, your doctor may prescribe Fragmin together with low-dose aspirin. This combination has been shown to be more effective than either agent alone in reducing the risk of heart attack and death, but it does increase the risk of bleeding. Your doctor will carefully balance these risks.
What Is the Correct Dosage of Fragmin?
Always use Fragmin exactly as your doctor has prescribed. The dose varies depending on the indication (treatment vs. prevention), your body weight, and your individual risk factors. Fragmin is injected subcutaneously (under the skin), typically into the abdomen or thigh, and should be given at the same time each day.
Your doctor will determine the appropriate dose based on your specific condition, body weight, kidney function, and other clinical factors. Do not change your dose or dosing schedule without consulting your doctor. The following dosage cards provide general guidance for the most common indications.
Adults
Treatment of DVT and Pulmonary Embolism
Dose: 200 IU/kg body weight once daily by subcutaneous injection, or 100 IU/kg twice daily. The maximum single dose should not exceed 18,000 IU. Treatment is typically initiated alongside oral anticoagulant therapy (warfarin) and continued for at least 5 days and until the INR is within the therapeutic range (2.0–3.0).
Cancer-Associated Thrombosis (Extended Treatment)
Month 1: 200 IU/kg once daily (maximum 18,000 IU/day).
Months 2–6: Approximately 150 IU/kg once daily. Treatment may be continued beyond 6 months at the discretion of the treating physician based on ongoing cancer treatment and thrombosis risk.
Surgical Thromboprophylaxis
Moderate risk surgery: 2,500 IU given 1–2 hours before surgery, followed by 2,500 IU once daily for 5–7 days or until the patient is fully mobile.
High risk surgery (e.g., orthopaedic, oncological): 5,000 IU the evening before surgery or 2,500 IU 1–2 hours before surgery followed by 2,500 IU 8–12 hours later, then 5,000 IU once daily for 5–7 days or longer as directed.
Medical Thromboprophylaxis (Acute Illness)
Dose: 5,000 IU once daily by subcutaneous injection, for patients with temporarily reduced mobility due to acute illness such as heart failure, severe infection, or respiratory disease. Treatment is continued for the duration of reduced mobility, typically 6–14 days.
Unstable Coronary Artery Disease
Dose: 120 IU/kg body weight (maximum 10,000 IU) every 12 hours by subcutaneous injection, administered with concurrent low-dose aspirin (75–325 mg daily). Treatment is typically continued for 6–8 days.
Anticoagulation During Haemodialysis
Chronic renal failure (no additional bleeding risk): A single intravenous bolus of 30–40 IU/kg followed by an infusion of 10–15 IU/kg/hour, or a single IV bolus of 5,000 IU at the start of each session.
Acute renal failure or patients with high bleeding risk: A single IV bolus of 5–10 IU/kg followed by an infusion of 4–5 IU/kg/hour. Adjustments are made based on anti-Xa levels and visual assessment of the extracorporeal circuit.
Children (1 Month to 17 Years)
| Age Group | Starting Dose | Frequency | Monitoring |
|---|---|---|---|
| 1 month to <2 years | 150 IU/kg | Twice daily | Anti-Xa levels after first dose; adjust to target range |
| 2 years to <8 years | 125 IU/kg | Twice daily | Anti-Xa levels after first dose; adjust to target range |
| 8 years to <18 years | 100 IU/kg | Twice daily | Anti-Xa levels after first dose; adjust to target range |
Paediatric doses are individually calculated by the treating physician based on the child’s body weight and age group. Anti-factor Xa blood levels are measured after the first dose and periodically throughout treatment to ensure the dose is within the therapeutic range. Parents or carers should never adjust the dose without consulting the doctor. Preservative-free formulations should be used for all paediatric patients.
Elderly Patients
No specific dose adjustment is routinely required for elderly patients. However, older adults are at increased risk of bleeding due to age-related decline in kidney function, reduced hepatic reserve, and the higher prevalence of concomitant medications. Doctors may choose to start with lower prophylactic doses and monitor more closely for signs of bleeding. Renal function assessment (creatinine clearance) is particularly important in elderly patients, as reduced clearance can lead to drug accumulation.
Missed Dose
If you forget to take a dose, take it as soon as you remember. However, if it is nearly time for your next scheduled dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. Inform your doctor if you have missed or believe you may have missed a dose, as gaps in anticoagulation coverage may increase the risk of blood clot formation, particularly in high-risk patients.
Overdose
If you have taken too much Fragmin, or if a child has accidentally received the medication, contact your doctor, go to the nearest emergency department, or call your local poison control centre immediately. Symptoms of overdose include excessive bleeding, bruising, blood in the urine or stool, and prolonged bleeding from wounds. The anticoagulant effect of dalteparin can be partially reversed with protamine sulfate, although protamine only neutralises approximately 25–50% of the anti-Xa activity of dalteparin. One milligram of protamine sulfate neutralises approximately 100 IU of dalteparin.
How to Inject Fragmin
Fragmin is injected subcutaneously (under the skin). It is not injected into a muscle (intramuscularly), as this significantly increases the risk of haematoma. If your doctor has prescribed Fragmin for home use, you will receive training from a healthcare professional on the correct injection technique before discharge.
Recommended injection sites:
- A U-shaped area around the navel on the abdomen (the most common site)
- The outer side of the middle of the thigh
Step-by-step injection guide:
- Wash your hands thoroughly with soap and water
- Clean the injection site with an alcohol swab and allow it to dry completely
- Sit or lie down in a comfortable position
- Pinch a fold of skin between your thumb and forefinger
- Insert the needle at a 90-degree angle (straight in) for adults, or 45–90 degrees for children
- Push the plunger slowly and steadily to inject the full dose
- Continue holding the skin fold throughout the injection
- Release the skin fold, then withdraw the needle straight out
- Apply gentle pressure to the site with cotton wool for 10 seconds – do not rub
- Rotate injection sites with each dose to prevent tissue damage
Do not inject into areas that are bruised, red, hard, or scarred. If using pre-filled syringes, do not expel the air bubble before injection, as this may result in loss of medication and a reduced dose. Dispose of used syringes and needles in a sharps container, and keep the container out of reach of children.
What Are the Side Effects of Fragmin?
Like all medicines, Fragmin can cause side effects, although not everyone gets them. Approximately 3 out of every 100 patients receiving Fragmin for prophylaxis experience side effects. The most common are injection-site reactions (bruising, pain) and mild thrombocytopenia. The most serious potential side effect is bleeding, which is dose-dependent.
The frequency and severity of side effects vary depending on the dose, duration of treatment, and the patient’s individual risk factors. Higher treatment doses carry a greater risk of bleeding compared to lower prophylactic doses. If you notice any side effects that concern you, or if existing side effects worsen, contact your doctor or pharmacist promptly.
Common
- Bruising at the injection site
- Pain or discomfort at the injection site
- Mild thrombocytopenia (reduced platelet count), usually transient and resolves during treatment
- Elevated potassium levels in the blood (hyperkalaemia), particularly in patients with chronic kidney disease or diabetes mellitus
- Bleeding (dose-dependent) – may manifest as nosebleeds, gum bleeding, blood in urine, or excessive bruising
- Transient elevation of liver enzymes (transaminases)
Uncommon
- Hypersensitivity reactions (skin rash, urticaria, itching)
Rare
- Skin necrosis (localised tissue death at or near the injection site)
- Transient alopecia (temporary hair loss)
Not Known
- Severe anaphylactic/anaphylactoid reactions with itching, skin rash, swelling (oedema), and difficulty breathing
- Skin rash (generalised)
- Retroperitoneal haemorrhage (bleeding behind the abdominal cavity), in some cases life-threatening
- Intracranial haemorrhage (bleeding in or around the brain), in some cases life-threatening
- Spinal or epidural haematoma (bleeding in or around the spinal cord), which can lead to paralysis
Signs of severe bleeding (blood in urine or stool, black tarry stools, coughing up blood, severe or unexplained bruising, persistent nosebleeds, dizziness or fainting); signs of severe allergic reaction (difficulty breathing, facial swelling, widespread rash); sudden severe headache, confusion, or weakness on one side of the body (possible intracranial haemorrhage); or sudden back pain, leg weakness, or loss of bladder/bowel control (possible spinal haematoma).
Children: The side effect profile in children is expected to be similar to that in adults, although there is limited data on potential adverse effects with long-term use in paediatric patients. Close monitoring of anti-Xa levels, platelet counts, and clinical signs of bleeding is essential throughout treatment.
Reporting Side Effects
Reporting suspected adverse reactions after a medicine has been approved is important for the ongoing monitoring of its benefit-risk balance. Healthcare professionals and patients are encouraged to report any suspected adverse reactions to their national pharmacovigilance authority (e.g., the FDA MedWatch programme in the United States, the Yellow Card Scheme in the United Kingdom, or the EMA EudraVigilance system in the European Union).
How Should You Store Fragmin?
Store Fragmin at or below 25°C (77°F). Keep the product out of the sight and reach of children. Do not use Fragmin after the expiry date printed on the packaging.
Fragmin should be stored at room temperature, not exceeding 25°C (77°F). Do not freeze Fragmin. Protect the product from light and keep it in the original packaging until ready for use. Check the expiry date (EXP) on the outer packaging before each use; the expiry date refers to the last day of the stated month.
For multi-dose vials (10,000 IU/ml and 25,000 IU/ml formulations containing benzyl alcohol preservative): once opened, diluted solutions remain stable for up to 48 hours at 25°C. From a microbiological standpoint, diluted solutions should ideally be used immediately after preparation. If not used immediately, in-use storage times and conditions are the responsibility of the user.
Pre-filled syringes are single-use only. Any unused product remaining in the syringe after injection should be discarded. Do not save or re-use partially used syringes.
Dispose of unused medicines and used syringes/needles in an appropriate sharps disposal container. Do not dispose of medicines in household waste or wastewater. Ask your pharmacist how to dispose of medicines you no longer use. These measures help protect the environment.
What Does Fragmin Contain?
The active substance in Fragmin is dalteparin sodium. Each millilitre contains either 2,500, 10,000, 12,500, or 25,000 IU of anti-Xa activity. Fragmin is a clear, colourless solution for injection available in pre-filled syringes and multi-dose vials.
Active Ingredient
Dalteparin sodium is the active pharmaceutical ingredient. It is a low molecular weight heparin produced by controlled nitrous acid depolymerisation of unfractionated heparin derived from porcine intestinal mucosa. The average molecular weight is approximately 6,000 daltons, with a range of 2,000 to 9,000 daltons.
Other Ingredients
- Pre-filled syringes: Water for injections. The 2,500 IU pre-filled syringe also contains sodium chloride
- Multi-dose vials without preservative: Sodium chloride, water for injections
- Multi-dose vials with preservative: Benzyl alcohol, water for injections
Available Presentations
Fragmin is a clear, colourless liquid supplied in the following presentations:
| Strength (IU) | Volume | Concentration | Pack Sizes |
|---|---|---|---|
| 2,500 IU | 0.2 ml | 12,500 IU/ml | 2, 10, 100 syringes |
| 5,000 IU | 0.2 ml | 25,000 IU/ml | 2, 5, 10, 25, 100 syringes |
| 7,500 IU | 0.3 ml | 25,000 IU/ml | 5, 10 syringes |
| 10,000 IU | 0.4 ml | 25,000 IU/ml | 2, 5, 30 syringes |
| 12,500 IU | 0.5 ml | 25,000 IU/ml | 2, 5, 30 syringes |
| 15,000 IU | 0.6 ml | 25,000 IU/ml | 2, 5, 30 syringes |
| 18,000 IU | 0.72 ml | 25,000 IU/ml | 2, 5, 30 syringes |
| Concentration | Volume | Preservative | Pack Size |
|---|---|---|---|
| 2,500 IU/ml | 4 ml vial | None (sodium chloride only) | 10 vials |
| 10,000 IU/ml | 10 ml vial | Benzyl alcohol | 1 vial |
| 25,000 IU/ml | 4 ml vial | Benzyl alcohol | 1 vial |
Frequently Asked Questions About Fragmin
Fragmin (dalteparin) is a low molecular weight heparin used to treat and prevent blood clots. Its main uses include treatment of deep vein thrombosis (DVT) and pulmonary embolism (PE), long-term prevention of blood clots in cancer patients, prevention of blood clots after surgery or during acute illness with reduced mobility, preventing clotting during kidney dialysis, and treating unstable coronary artery disease (unstable angina and non-ST-elevation myocardial infarction). It is also approved for treating VTE in children aged 1 month and older.
Fragmin is injected subcutaneously (under the skin), typically into the abdomen (a U-shaped area around the navel) or the outer side of the mid-thigh. Before self-injecting, you will receive hands-on training from a healthcare professional. Pinch a fold of skin, insert the needle at a 90-degree angle, inject slowly, and then withdraw the needle. Do not rub the injection site afterwards. Rotate sites with each injection to reduce bruising. If using a pre-filled syringe, do not expel the air bubble before injecting. Dispose of used needles in a sharps container.
The most common side effects include bruising and pain at the injection site, mild reduction in platelet count (thrombocytopenia) that usually resolves on its own, elevated potassium levels in the blood (particularly in patients with kidney disease or diabetes), dose-dependent bleeding, and transient increases in liver enzymes. About 3% of patients receiving prophylactic doses experience side effects. Serious but rare side effects include severe allergic reactions, retroperitoneal haemorrhage, intracranial haemorrhage, and spinal or epidural haematoma.
Yes, Fragmin is considered one of the preferred anticoagulants during pregnancy. Unlike warfarin, dalteparin does not cross the placenta and therefore does not pose a risk of foetal harm. However, multi-dose vials containing benzyl alcohol preservative must be avoided during pregnancy, as benzyl alcohol can cross the placenta. Preservative-free pre-filled syringes should be used instead. Your doctor will determine the appropriate dose and monitoring schedule based on your individual clinical situation.
Fragmin, warfarin, and direct oral anticoagulants (DOACs like apixaban and rivaroxaban) are all blood thinners but differ in key ways. Fragmin is given by injection and acts quickly (within hours), while warfarin and DOACs are taken orally. Warfarin requires regular INR blood monitoring and has many food/drug interactions; Fragmin and DOACs generally do not. Fragmin is preferred in cancer-associated thrombosis, pregnancy, and patients with severe kidney impairment where DOACs may not be suitable. DOACs are more convenient for long-term outpatient use due to oral administration. Your doctor will choose the most appropriate agent based on your specific clinical situation.
If you miss a dose, take it as soon as you remember. If it is almost time for your next scheduled dose, skip the missed dose and continue with your regular schedule. Never take a double dose. Inform your doctor that you missed a dose, as gaps in anticoagulation coverage may increase the risk of blood clot formation, particularly if you are at high risk. Try to take Fragmin at the same time each day to help establish a routine and reduce the chance of missing doses.
References
- Lee AYY, Levine MN, Baker RI, et al. Low-molecular-weight heparin versus a coumarin for the prevention of recurrent venous thromboembolism in patients with cancer (CLOT trial). N Engl J Med. 2003;349(2):146-153. doi:10.1056/NEJMoa025313
- Konstantinides SV, Meyer G, Becattini C, et al. 2019 ESC Guidelines for the diagnosis and management of acute pulmonary embolism. Eur Heart J. 2020;41(4):543-603. doi:10.1093/eurheartj/ehz405
- Kearon C, Akl EA, Ornelas J, et al. Antithrombotic Therapy for VTE Disease: CHEST Guideline and Expert Panel Report. Chest. 2016;149(2):315-352. doi:10.1016/j.chest.2015.11.026
- Lyman GH, Carrier M, Ay C, et al. American Society of Hematology 2021 guidelines for management of venous thromboembolism: prevention and treatment in patients with cancer. Blood Adv. 2021;5(4):927-974. doi:10.1182/bloodadvances.2020003442
- National Institute for Health and Care Excellence (NICE). Venous thromboembolic diseases: diagnosis, management and thrombophilia testing. NICE Guideline [NG158]. Updated 2024.
- World Health Organization. WHO Model List of Essential Medicines – 23rd List (2023). Geneva: WHO; 2023.
- Bates SM, Rajasekhar A, Engel M, et al. American Society of Hematology 2018 guidelines for management of venous thromboembolism: venous thromboembolism in the context of pregnancy. Blood Adv. 2018;2(22):3317-3359. doi:10.1182/bloodadvances.2018024802
- Monagle P, Chan AKC, Goldenberg NA, et al. Antithrombotic therapy in neonates and children: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines. Chest. 2012;141(2 Suppl):e737S-e801S. doi:10.1378/chest.11-2308
- European Medicines Agency (EMA). Fragmin – Summary of Product Characteristics. Accessed January 2026.
- British National Formulary (BNF). Dalteparin sodium. National Institute for Health and Care Excellence. Accessed January 2026.
Editorial Team
iMedic Medical Editorial Team – Specialists in Haematology and Clinical Pharmacology
iMedic Medical Review Board – Independent panel of medical experts
Level 1A – Systematic reviews and meta-analyses of randomised controlled trials
WHO, ESC, ACCP, ASH, NICE, ISTH – GRADE evidence framework
This article was written by licensed medical professionals and reviewed according to international medical standards. All claims are supported by peer-reviewed research and current clinical guidelines. No commercial funding was received. Last fact-check: .