VITAMINS & SUPPLEMENTS · GUIDE
Questions to Ask Your Clinician or Pharmacist About Omega-3 Supplements
A list of questions to bring to a doctor, nurse or pharmacist about omega-3 or fish oil, with the research behind each question and no advice on what to take.
Content last updated . This page has not been medically reviewed.
Back to Omega Fatty AcidsWhy bring questions
Omega-3 products range from fish and fish oil to algal oil, krill oil and prescription medicines, and they are not the same thing. NCCIH, part of the US National Institutes of Health, advises talking with your health care providers about any complementary health approach you use, so you can make shared, well-informed decisions. [1] This page gives you questions and the reason behind each one. It does not tell you what to take. The answers depend on your health, medicines and plans, and only a clinician or pharmacist who knows them can give them.Bring the product itself, or a photo of the Supplement Facts panel, so the pharmacist can read the EPA and DHA lines. See a fish oil label checklist for what to look at.
Questions about whether it fits you
Is there a reason for me to take omega-3 at all, or is food enough?
UnclearNCCIH says that for some health conditions the evidence for benefits from seafood is stronger than for omega-3 supplements. [1] See Are omega-3 supplements necessary?.
What would we be trying to change, and how would we know it worked?
UnclearA change in a blood marker is not the same as a clinical outcome. Trials differ by product, amount, group and comparator.
Is a prescription omega-3 medicine relevant to me, and how is it different from a supplement?
UnclearNCCIH notes prescription products are approved for very high triglycerides, differ in composition, and may not have the same effects as supplements. [1] See prescription omega-3 vs supplements.
Does my heart rhythm history matter?
UnclearA pooled analysis of seven large trials found more atrial fibrillation with marine omega-3 supplements, with greater risk in trials using more than 1 g a day. [2]
Questions about medicines and bleeding
Do any of my medicines, especially blood thinners, interact?
ModerateA meta-analysis of 15 trials reported no significant difference in bleeding-related disorders overall, but warned about bleeding with prescription EPA ethyl ester. [3]
Does the product type change the answer?
UnclearOne study in healthy adults found prescription icosapent ethyl at 4 g a day did not change the effect of a single warfarin dose. [4] That was a prescription product, healthy volunteers and one dose, so it cannot be applied to other products or to people who take warfarin long term.
Should my surgery or dental team know?
UnclearTell your surgical team about every supplement. See supplements before surgery and medication interactions.
Do not stop or change a prescribed medicine without talking to the person who prescribed it.
Questions about your situation
- I am pregnant, trying for a baby or breastfeeding. What is safe? The NHS advises avoiding fish liver oil supplements in pregnancy or when trying for a baby unless a GP advises otherwise, because they are high in vitamin A. [5] It also says no more than 2 portions of oily fish a week. [5] See pregnancy and breastfeeding safety.
- I have a fish or shellfish allergy. The NHS says these allergies can cause severe reactions. [5] Ask the pharmacist to check ingredients and sources. Sudden swelling of the lips, mouth, throat or tongue, or struggling to breathe, are emergency signs; call 911 in the US. [6]
- I have a kidney or liver condition, or take many medicines. Ask whether anything about your condition changes the question. We did not find a source on this in the pages we read for this checklist, so see kidney and liver evidence.
- This is for a child or teenager. Ask whether it is appropriate at all. See omega-3 for children and teens.
Questions about the product
- Which of the EPA and DHA lines tells me how much I would get from one serving? On a US label the serving may be several capsules. [7]
- Is there independent testing I should look for? See quality testing and certifications.
- How should I report side effects? Common ones include unpleasant taste, bad breath, heartburn, nausea and diarrhea. [1]
How to use the answers
Write down the answers and the date. Ask for a review if your medicines, health or plans change. If you feel unwell after starting any supplement, contact a clinician or pharmacist. For a poisoning or overdose emergency in the US, call Poison Help at 1-800-222-1222, and call 911 for an emergency.Frequently asked questions
Should I ask my doctor before taking fish oil?
It is reasonable to, and NCCIH encourages telling your health care providers about any complementary health approach you use. [1]
Can a pharmacist help even if I buy it without a prescription?
Yes. A pharmacist can check the label and your medicines. Bring the label.
What if I take a blood thinner?
Ask before starting. The research on bleeding differs by product, and a trial of one prescription product in healthy adults does not cover others. [3] [4]
Do I need to tell my surgeon?
Yes, tell your surgical team and pharmacist about all supplements. See the page on supplements before surgery linked above.
Is food a better first question than a pill?
NCCIH says that for some health conditions the evidence for seafood is stronger than for supplements, which is a fair thing to raise. [1]