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dalteparin

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Brand names: Fragmin

Low-Molecular-Weight Heparin Rx

Dalteparin (Fragmin) is a type of blood thinner medicine. It helps prevent and treat harmful blood clots.

What it does

This medicine can help prevent blood clots in your legs after surgery or during illness with limited movement.

Common side effects

Bleeding, Bruising at the injection site, Pain at the injection site

Key warnings

This medicine can cause bleeding around your spine if you get an epidural or spinal tap.

How It Works

Dalteparin is a low molecular weight heparin. It works by blocking certain proteins in your blood that help clots form. This helps to prevent new clots from forming and keeps existing clots from getting bigger.

How to Take It

Dalteparin is given as a shot under the skin. The dose depends on your condition and weight. Your doctor will tell you how much to take and how often. Follow their instructions carefully.

Pregnancy & Breastfeeding

Tell your doctor if you are pregnant or breastfeeding. This medicine should only be used during pregnancy if clearly needed. Dalteparin passes into breast milk in small amounts, but the effect on the baby is not known.

Missed Dose

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your regular schedule.

Storage

Store at room temperature, away from heat and light.

Side Effects (from patient reports)

Based on 5,326 FDA adverse event reports.

Feeling sick to your stomach
675
Using the medicine for something it's not approved for
659
Blood clot in the lungs
570
Difficulty breathing
563
Throwing up
545
Stomach pain
490
Fever
472
Blood infection
463
Loose stools
457
Feeling tired
432

FDA Adverse Event Report Analysis

Detailed analysis of 10,243 reports from the FDA Adverse Event Reporting System (FAERS). Reports span 2003–2025.

Total Reports

10,243

Death-Related Reports

2,222

Hospitalization Reports

5,327

Top Indication

Product Used For Unknown Indication

Gender Distribution

Female 4,692 (51%)
Male 4,420 (48%)

Age Distribution

0–17 274
18–44 1,243
45–64 2,329
65–74 1,874
75+ 2,068

Most Reported Adverse Reactions (FAERS)

# Reaction Reports
1 NAUSEA 672
2 OFF LABEL USE 659
3 PULMONARY EMBOLISM 570
4 DYSPNOEA 563
5 VOMITING 545
6 ABDOMINAL PAIN 489
7 PYREXIA 472
8 SEPSIS 462
9 DIARRHOEA 457
10 FATIGUE 431
11 GENERAL PHYSICAL HEALTH DETERIORATION 419
12 CONSTIPATION 414
13 DEATH 406
14 ANAEMIA 400
15 PNEUMONIA 373

Reactions in Death Reports

DEATH 406
NAUSEA 348
SEPSIS 340
GENERAL PHYSICAL HEALTH DETERIORATION 330
MULTIPLE ORGAN DYSFUNCTION SYNDROME 318
VOMITING 313
ABDOMINAL PAIN 294
CONSTIPATION 278
OFF LABEL USE 260
ABDOMINAL DISTENSION 259

Reactions in Hospitalization Reports

DYSPNOEA 411
NAUSEA 402
PYREXIA 385
PULMONARY EMBOLISM 351
VOMITING 348
OFF LABEL USE 342
DIARRHOEA 335
ANAEMIA 327
PNEUMONIA 296
ABDOMINAL PAIN 284

Source: FDA FAERS (Adverse Event Reporting System) FDA FAERS (Adverse Event Reporting System) Reports are voluntary and do not establish causation

Serious Warnings

This medicine can cause bleeding around your spine if you get an epidural or spinal tap. This can lead to long-term or permanent paralysis. Tell your doctor if you are taking other medicines that can increase bleeding, like NSAIDs or aspirin.

Common Questions

What should I do if I have bleeding?
Tell your doctor right away if you have any unusual bleeding or bruising.
Can I take aspirin with dalteparin?
Your doctor may tell you to take aspirin with dalteparin for certain conditions. Follow your doctor's instructions.
How long will I need to take dalteparin?
The length of treatment depends on your condition. Your doctor will tell you how long to take it.
Can dalteparin be given as an intramuscular injection?
No, dalteparin should not be given as an intramuscular injection.
Can I mix dalteparin with other injections or infusions?
No, dalteparin should not be mixed with other injections or infusions.
What if I am allergic to latex?
The needle shield of the prefilled syringe may contain natural rubber latex. Tell your doctor if you are allergic to latex.
What if I have kidney problems?
Tell your doctor if you have kidney problems, as the dose may need to be adjusted.
Can I take dalteparin before surgery?
Your doctor will tell you when to start and stop dalteparin before any surgery or procedure.
What if I am taking other medications?
Tell your doctor about all the medications you are taking, including over-the-counter drugs and supplements.
How will I know if the medicine is working?
Your doctor will monitor you to see if the medicine is working.
What are the common side effects of dalteparin?
The most commonly reported side effects of dalteparin include Bleeding, Bruising at the injection site, Pain at the injection site, Increased liver enzymes. Based on 5,326 FDA adverse event reports. Always consult your healthcare provider about potential side effects.
What drug class is dalteparin?
dalteparin belongs to the Low-Molecular-Weight Heparin drug class. It requires a prescription (Rx). This medicine can help prevent blood clots in your legs after surgery or during illness with limited movement.
Is dalteparin safe during pregnancy?
Tell your doctor if you are pregnant or breastfeeding. This medicine should only be used during pregnancy if clearly needed. Always consult your healthcare provider before using any medication during pregnancy or breastfeeding.

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What the FDA Data Shows for dalteparin

The FDA label for dalteparin (sold under brand names such as Fragmin) classifies it as a prescription-only medication in the Low-Molecular-Weight Heparin class. This medicine can help prevent blood clots in your legs after surgery or during illness with limited movement. Official labeling lists 4 commonly reported side effects, including Bleeding, Bruising at the injection site, Pain at the injection site.

Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 5,326 voluntary reports. Interaction data is drawn directly from FDA-approved prescribing information. Acquisition-cost data is surveyed weekly by CMS and updated as manufacturers report changes.

Report counts do not establish causation — a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history, and patent information further shape supply and switching decisions. This page summarizes public FDA data for educational purposes only and is not a substitute for professional medical advice — always consult a licensed healthcare provider before starting, stopping, or changing any medication.

Data Sources

Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS).

FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. Always consult a healthcare professional before making medication decisions.

Last updated: September 30, 2025

All federal data sources used on this page