The short answer
Fish oil has not been shown to increase bleeding in a large cardiac-surgery trial, so blanket avoidance is not supported by that evidence. The trial did not report a dalteparin-specific result, leaving the exact combination less certain.
What this answer covers
Oral mixed EPA+DHA fish-oil products with subcutaneous dalteparin sodium; isolated high-dose EPA, other oils and different formulations require separate assessment. Fish oil already contains omega-3 fatty acids; adding another omega-3 product changes total exposure and is not a separate proven interaction.
- Supplement or preparation
- Fish Oil
- Medication ingredient
- dalteparin
A large trial measured actual bleeding
In 1,516 cardiac-surgery patients, prescription fish oil did not increase major perioperative bleeding versus placebo. The estimate was compatible with some uncertainty, and the fish-oil group received fewer transfused blood units. This is more informative than platelet tests alone.
Dalteparin applicability is indirect
The analysis found no significant difference in the treatment effect by preoperative antithrombotic therapy or bypass use. However, it did not isolate dalteparin dose, route or co-use outcomes. It cannot provide a precise risk for an individual dalteparin regimen.
The formulation matters
The study used a prescription mixture of EPA and DHA in ethyl-ester capsules. A generic fish-oil label may describe a different concentration or preparation, and isolated EPA is not the same exposure. The study regimen is not a self-treatment recommendation.
No universal spacing or stopping rule
The evidence does not establish a protective dosing gap or a need for everyone receiving dalteparin to stop fish oil. Give the treatment or surgical team the exact product and amount so they can make an individual plan. Report bleeding promptly and do not alter dalteparin yourself.
Evidence and practical considerations
Side effects & toxicity
No direct dalteparin clinical bleeding evidence; indirect original human findings include null results and cannot establish this broad increased-risk claim.
- Exact scope
- Oral mixed EPA+DHA fish-oil products with subcutaneous dalteparin sodium; isolated high-dose EPA, other oils and different formulations require separate assessment. Fish oil already contains omega-3 fatty acids; adding another omega-3 product changes total exposure and is not a separate proven interaction. with Subcutaneous dalteparin sodium; active ingredient bridge to RxCUI67109 IN. Not UFH or another LMWH.
- Medication form and route
- subcutaneous dalteparin; oral supplement
What remains uncertain
- Source-specific population, preparation and endpoint limits apply; no universal dose or timing rule.
Factors that may matter: Exact preparation; Dose and duration; Kidney function; Other medicines.
Read the supporting source summaries
Source 1: current product label
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: Patients receiving subcutaneous dalteparin sodium.
Bleeding risk can increase with platelet inhibitors and other anticoagulants. Hyperkalemia is listed among postmarketing reports, whose frequency and causal relationship cannot reliably be established.
How this applies: Exact dalteparin sodium injection product and route; no silent transfer of unfractionated-heparin dosing or monitoring rules.
Does not specifically name these supplements. Not unfractionated heparin, another LMWH, an oral anticoagulant or topical therapy.
Source 2: original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 1,516 cardiac-surgery patients.
Major perioperative bleeding was not increased (OR0.81,95%CI0.53–1.24); fewer transfused units in fish-oil group. No significant effect modification by baseline antithrombotics or bypass use.
How this applies: Exact species, preparation, route and measured endpoints govern applicability; other anticoagulants are not silently treated as dalteparin.
Secondary safety analysis; no dalteparin-specific exposure or treatment subgroup reported. Mixed EPA+DHA is not isolated EPA, and dose reflects fish-oil product rather than pure EPA+DHA mass.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Article prepared | |
| Prepared exact dalteparin article with independently checked product label and explicit limits on indirect supplement evidence. | |
| Research summary published |
Article revision: 495b304fab83dc25
This guide brings together the evidence records used by our interaction checker. Each finding retains its own preparation limits, research date, and source summaries.
Full citations require verification. Reading this answer and the source summaries does not.
Taking other supplements or medications?
Use the checker to explore your other combinations. Ask a pharmacist to review the exact products, amounts and medical conditions in your complete list.
Open the interaction checkerInformation, not medical advice. Do not change prescribed treatment based on this guide.