What are the side effects of fish oil supplements?

Dr. Goldina Erowele
Caregiving Specialist

Make sure you check with your Physician before taking Fish oil. High doses may cause gastrointestinal upset, loose stools and nausea.

Use with caution in individuals with diabetes or in those who may be predisposed to hypoglycemia; may alter glucose regulation. Contraindicated in individuals with active bleeding (e.g., peptic ulcer, intracranial bleeding). Use with caution in individuals with a history of bleeding, and in individuals taking anticoagulant medications, including warfarin, aspirin, aspirin-containing products, NSAIDs or antiplatelet agents (e.g., ticlopidine, clopidogrel, dipyridamole).

Discontinue use prior to dental or surgical procedures (generally at least 14 days before).

Use with caution in individuals who are allergic to seafood.

Answers to questions regarding information about medications or health conditions are not for diagnostic or treatment purposes and are not conclusive as to the presence or absence of any health condition. Individuals using this site are encouraged to consult the healthcare provider regarding their specific medical condition. Information provided here does not constitute medical advice, diagnosis, or treatment.

Dr. Grant Cooper, MD
Physical Medicine & Rehabilitation Specialist

Omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and gamma-linolenic acid (GLA) oils thin the blood. If you bleed easily, have a diagnosed bleeding disorder, are taking a blood-thinning medication, discuss their risks and benefits with your physician. Because of their ability to thin the blood, combining different omega-3 fatty acid supplements is not recommended, though occasionally it might be warranted. Note that non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen and naproxen, also increase clotting time.

The more common side effects of fish oil supplements include a "fishy" smelling burp or taste in the mouth, or slight gastrointestinal upset and gas. If you experience any of these mild symptoms, discuss them with your doctor and consider decreasing the dosage to 1,000 mg of EPA/DHA. You can slowly increase the dosage back to 3,000 mg per day as your symptoms resolve.

The Arthritis Handbook: Improve Your Health and Manage the Pain of Osteoarthritis (A DiaMedica Guide to Optimum Wellness)

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The Arthritis Handbook: Improve Your Health and Manage the Pain of Osteoarthritis (A DiaMedica Guide to Optimum Wellness)

According to conventional wisdom, arthritis pain is an inevitable part of aging. Not so, says Dr. Grant Cooper in this practical, accessible guide. For those who do develop osteoarthritic conditions,...
Dr. Jacob Teitelbaum
Integrative Medicine Specialist

Although many people find fish oil supplementation to be very helpful, many also find it to be a bit tricky to take because of having to take so many fish oil supplements to meet their dosage needs and the "fish burp" digestive issues that sometimes result. It's an unfortunate side effect that occurs in some cases, but is not prevalent enough that chronic fatigue syndrome (CFS) and fibromyalgia patients should forgo this important dietary need.

Stacy Wiegman, PharmD
Pharmacy Specialist

The most immediately noticeable side effects of taking fish oil supplements are likely to be fishy breath, burping, heartburn and possibly nausea or diarrhea. Taking supplements with meals or freezing them can minimize these problems.

Taking high doses of fish oil may reduce the ability of your blood to clot, causing excessive bleeding. Taking them for a long period of time may lead to vitamin E deficiency and may increase risk for anemia in menstruating women. Fish oil supplements may also interact with blood thinners and blood pressure medications, increasing the effect of these drugs. For all these reasons, be sure to talk to your doctor before taking fish oil supplements.

The Food and Drug Administration (FDA) considers fish oil supplements to be "generally regarded as safe" or GRAS. And certainly when used as an anti-inflammatory, fish oil allows for fewer severe side effects than prescribed non-steroid anti-inflammatory drugs (NSAID). But as with everything there are some side effects.

With extended use or high doses of fish oil, gastrointestinal discomfort, reflux or diarrhea are common side effects. Additionally, if you ingest a lot of fish oil, the levels of vitamin E in your blood can be lowered. So, many marketers of fish oil supplements will add vitamin E to their products. And some people remark on the fishy taste that lingers in their mouths.

People with a fish allergy should not use fish oil. There are also some medical conditions which preclude use of such supplements. Since fish oil may reduce clotting in the blood anyone taking medications such as Coumadin or NSAIDs which thin the blood should not ingest fish oil.

Another factor for consideration is the prevalence of pollution in our water and its impact on fish. Certain types of fish carry elevated levels of PCBs or dioxins or mercury. Toxins such as methylmercury do pose a health threat to people who ingest large quantities of shark, tuna or swordfish. Yet, fish oil is deemed non-toxic because mercury only builds up in the flesh of fish, not in its oils.

Continue Learning about Dietary Supplements

Dietary Supplements

Whether you're visiting the drug store, grocery or natural food shop you'll likely find an aisle where there are jars and bottles of things for you to put in your body that are neither foods nor medicines. Ranging from vitamins an...

d minerals to fiber and herbal remedies, these supplements are not regulated in the same way as either food or medicine. Some of them are backed by solid research, others are folk remedies or proprietary cures. If your diet does not include enough of certain vitamins or minerals, a supplement may be a good idea. Natural treatment for conditions like constipation may be effective. But because these substances are unregulated, it is always a good idea to educate yourself about the products and to use common sense when taking them. This is even more true if you are pregnant or taking a medicine that may be affected by supplements.

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.