Prescription medication · Low-Molecular-Weight Heparin
dalteparin
Also sold as Fragmin. This medicine can help prevent blood clots in your legs after surgery or during illness with limited movement.
Data updated 2026-05-15
- 10,243
- FDA reportsModerately reported
- Rx
- Availability
dalteparin (Fragmin) is a prescription Low-Molecular-Weight Heparin. This medicine can help prevent blood clots in your legs after surgery or during illness with limited movement.
Dalteparin (Fragmin) is a type of blood thinner medicine. It helps prevent and treat harmful blood clots.
Verify with FDA → · CMS NADAC pricing →
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.
The sections below are summarized in plain English from dalteparin's FDA-approved prescribing information. They describe what the official label says, and are not personal medical advice.
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.
This is a plain-language summary of dalteparin's FDA labeling, not individualized dosing advice. Ask a pharmacist or prescriber before changing how you take this medication.
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.
This is a plain-language summary of dalteparin's FDA labeling, not individualized advice. Ask a pharmacist or prescriber about pregnancy or breastfeeding on this medication.
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.
This is a plain-language summary of dalteparin's FDA labeling, not individualized advice. Ask a pharmacist or prescriber what to do about your specific missed dose.
Storage
Store at room temperature, away from heat and light.
Side Effects (from patient reports)
Based on 10,243 FDA adverse event reports.
Most-reported reactions
Adverse reactions in FAERS for dalteparin, by number of reports
- Feeling sick to your stomach
Feeling sick to your stomach
675 reports
- Blood clot in the lungs
Blood clot in the lungs
570 reports
- Difficulty breathing
Difficulty breathing
563 reports
- Throwing up
Throwing up
545 reports
- Stomach pain
Stomach pain
490 reports
- Fever
Fever
472 reports
- Blood infection
Blood infection
463 reports
- Loose stools
Loose stools
457 reports
- Feeling tired
Feeling tired
432 reports
- Overall decline in physical health
Overall decline in physical health
421 reports
What this shows Bars show how often each reaction was reported, not how likely it is to happen, a report records a temporal association, never proof that the drug caused it.
Reports over time
Adverse-event reports filed for dalteparin each year to the FDA Adverse Event Reporting System (FAERS).
Year-to-year volume tracks usage, prescribing, and scrutiny, not a change in per-patient risk. Source: FDA FAERS.
Where dalteparin sits
dalteparin has more FDA adverse-event reports than 40% of the drugs FAERS tracks. A high position reflects how widely a drug is used and watched, not how dangerous it is.
Percentile across all drugs PlainMeds tracks by FAERS report volume. The dot is dalteparin; the line is the median (50th percentile).
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
Reports Mentioning Death
2,222
21.7% of reports — not proof of cause
Hospitalization Reports
5,327
Top Indication
Product Used For Unknown Indication
Gender Distribution
Age Distribution
Most Reported Adverse Reactions (FAERS)
| # | Reaction | Reports |
|---|---|---|
| 1 | NAUSEA | 672 |
| 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 |
| 16 | CONDITION AGGRAVATED | 365 |
Reactions in Death Reports
Reactions in Hospitalization Reports
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?
Can I take aspirin with dalteparin?
How long will I need to take dalteparin?
Can dalteparin be given as an intramuscular injection?
Can I mix dalteparin with other injections or infusions?
What if I am allergic to latex?
What if I have kidney problems?
Can I take dalteparin before surgery?
What if I am taking other medications?
How will I know if the medicine is working?
What are the common side effects of dalteparin?
What drug class is dalteparin?
Is dalteparin safe during pregnancy?
Related Medications in Low-Molecular-Weight Heparin
Other drugs grouped near dalteparin - same-class peers and common alternatives.
apixaban
Eliquis
Apixaban (Eliquis) is a medicine that helps prevent blood clots.
Compare with dalteparin →
aspirin
Bayer, Ecotrin
Aspirin is a common medicine used to relieve minor pain.
Compare with dalteparin →
cilostazol
Pletal
Cilostazol is a medicine that helps improve walking distance in people with leg pain due to poor circulation.
Compare with dalteparin →
clopidogrel
Plavix
Clopidogrel is a drug that helps to prevent blood clots.
Compare with dalteparin →
dabigatran
Pradaxa
Dabigatran (Pradaxa) is a drug that helps to prevent blood clots from forming.
Compare with dalteparin →
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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 10,243 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
Read our methodology - how this data is sourced, computed, and verified.
Data currency: FDA FAERS adverse-event reports through 2025, CMS NADAC acquisition-cost pricing effective December 2024, compiled and last refreshed May 2026. See our methodology for per-source dates and refresh cadence. Spot a figure that looks wrong? Report a correction.
All federal data sources used on this page
- FDA Orange Book - approved drug products with therapeutic equivalence. accessdata.fda.gov/cder/ob
- FDA DailyMed - NIH-hosted drug labeling for FDA-approved meds. dailymed.nlm.nih.gov
- FDA Adverse Event Reporting System (FAERS) - post-marketing safety surveillance. fda.gov/drugs/faers
- NLM RxNorm - standardized clinical drug nomenclature. nlm.nih.gov/research/umls/rxnorm
- CMS Medicare Part B Drug Average Sales Price Files - federal drug pricing data. cms.gov/medicare/part-b-drugs/asp
- FDA Drug Shortages Database - current and resolved drug shortage tracking. accessdata.fda.gov/drugshortages