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Fragmin Side Effects

Generic name: dalteparin

Medically reviewed by Last updated on Aug 9, 2023.

Note: This document contains side effect information about dalteparin. Some dosage forms listed on this page may not apply to the brand name Fragmin.

Applies to dalteparin: subcutaneous solution.


Subcutaneous route (Solution)

Patients anticoagulated with low molecular weight heparins or heparinoids who receive neuraxial anesthesia or undergo a spinal puncture are at risk for epidural or spinal hematomas, which may result in long-term or permanent paralysis. The use of indwelling epidural catheters, concomitant drugs that also affect hemostasis (eg, NSAIDs, platelet inhibitors, or other anticoagulants), history of traumatic or repeated epidural or spinal punctures, or history of spinal deformity or spinal surgery further increase this risk. The optimal timing of dalteparin administration and a neuraxial procedure is unknown. Frequent monitoring for signs and symptoms of neurological impairment is recommended. Seek urgent treatment if neurological compromise occurs.

Serious side effects of Fragmin

Along with its needed effects, dalteparin (the active ingredient contained in Fragmin) 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 immediately if any of the following side effects occur while taking dalteparin:

More common

Less common


Incidence not known

Other side effects of Fragmin

Some side effects of dalteparin may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Incidence not known

For Healthcare Professionals

Applies to dalteparin: subcutaneous solution.


The most common side effects were any bleeding, postoperative transfusion, transaminase increases, and injection site pain.[Ref]


A bleeding reaction was considered major if accompanied by a decrease in hemoglobin of 2 g/dL or greater in connection with clinical symptoms, a transfusion was required, bleeding led to interruption of treatment or death, bleeding caused a significant clinical event, bleeding resulted in reoperation, or retroperitoneal or intracranial bleeding occurred.[Ref]

Very common (10% or more): Any bleeding (up to 18.5%)

Common (1% to 10%): Major bleeding reactions

Postmarketing reports: Prosthetic cardiac valve thrombosis[Ref]


Very common (10% or more): Postoperative transfusion (up to 15.9%)

Common (1% to 10%): Wound hematoma, reoperation due to bleeding[Ref]


Very common (10% or more): Grades 2 through 4 increases in AST and ALT (up to 14%)

Common (1% to 10%): Asymptomatic increases in transaminase levels (serum glutamic oxaloacetic transaminase/AST and Serum glutamic pyruvic transaminase/ALT) greater than 3 times the upper limit of normal, grades 3 and 4 increases in AST and ALT[Ref]

Nervous system

Postmarketing reports: Epidural/spinal hematoma, intracranial bleed[Ref]


Very common (10% or more): Injection site pain (up to 12%)

Common (1% to 10%): Injection site hematoma[Ref]


Common (1% to 10%): Reversible non-immunologically-mediated thrombocytopenia (type I)

Rare (less than 0.1%): Immunologically-mediated heparin-induced thrombocytopenia (type II, with or without associated thrombotic complications)[Ref]


Common (1% to 10%): Hematuria[Ref]


Uncommon (0.1% to 1%): Allergic reaction

Rare (less than 0.1%): Fever

Frequency not reported: Anaphylactoid reaction[Ref]


Uncommon (0.1% to 1%): Rash, urticaria, pruritus

Rare (less than 0.1%): Bullous eruptions, skin necrosis, alopecia[Ref]


Uncommon (0.1% to 1%): Hypersensitivity[Ref]


Uncommon (0.1% to 1%): Hyperkalemia[Ref]


Uncommon (0.1% to 1%): Osteoporosis[Ref]


Postmarketing reports: Hypoaldosteronism[Ref]


Frequency not reported: Gastrointestinal bleeding

Postmarketing reports: Retroperitoneal bleed[Ref]


Frequency not reported: Serum creatinine increased[Ref]


1. (2001) "Product Information. Fragmin (dalteparin)." Pharmacia and Upjohn

2. Cerner Multum, Inc. "UK Summary of Product Characteristics."

3. Cerner Multum, Inc. "Australian Product Information."

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.