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Overview: Omega-3 supplements, which are available over the counter, are used to increase your omega-3 fatty acid levels. Common side effects of omega-3 supplements may include having a bad taste in your mouth or bad breath, heartburn, nausea, upset stomach, and diarrhea. Before taking omega-3 supplements, tell your health care provider about all of your health conditions, including any food allergies, and any medicines or supplements you may be using.

Uses

What are omega-3 supplements (fish oil) used for?

Omega-3 supplements are commonly used to raise omega-3 fatty acid levels in your body. The benefits of omega-3 supplements for other uses are not well defined.

Omega-3 supplements may also be used for other conditions as determined by your health care provider.

A specific form of omega-3 is available as a prescription. See: Omega-3-Acid Ethyl Esters (Lovaza, Omacor, Triklo)

How do omega-3 supplements work (mechanism of action)?

Omega-3 supplements are often made from fish or krill and sometimes referred to as fish oil or krill oil supplements. Some omega-3 supplements are made from algae and may be called algal oil supplements. Supplements made from algae are considered vegetarian.

Omega-3 supplements have one or more omega-3 fatty acids in them. These fatty acids are an important part of many cells in your body, especially in your eyes and brain. Omega-3 fatty acids give you calories for energy and help with many functions in your heart, blood vessels, lungs, and immune system, and with certain hormones.

In the United States, most people get enough omega-3 fatty acids from their diet. Omega-3 fatty acids come in many forms. One common form is alpha-linolenic acid (ALA) that is mostly found in plants and plant oils, such as seeds, nuts, flaxseed oil, and canola oil. Two other common omega-3 fatty acids are docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). These two fatty acids are found in krill, fish (especially fatty fish, such as cod, salmon, tuna, and mackerel), and some fortified foods, including eggs, yogurt, juices, milk, soy drinks, and baby formulas. 

For most adults, the recommended daily intake of ALA should be between 1.1 and 1.6 grams (g). It is rare not to get enough ALA from your diet. For most adults, there is no recommended daily intake for DHA or EPA. However, there are recommended intakes for some adults, such as those with heart disease or those who are pregnant or breastfeeding (see the Sources section for more details). Most people can get enough DHA and EPA by eating two to three servings of low-mercury fish each week. Talk with your health care provider about the best way to get the recommended amounts of omega-3. 

How are omega-3 supplements supplied (dosage forms)?

Brands and other names

  • Magna Omega-3
  • MegaRed
  • Oslomega
  • Ultimate Omega

Dosage forms and strengths

Omega-3 supplements are available as a dietary supplement in various strengths and dosage forms to provide omega-3 fatty acids such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Some products may contain other ingredients such as vitamin E or probiotics.

How should I store omega-3 supplements?

Omega-3 supplements should be stored according to the product label. Most medicines should be kept in a cool, dry location that is out of the reach of children and pets and not in direct sunlight.

Side Effects

What are the most common side effects of omega-3 supplements?

The most common side effects of omega-3 are listed below. Tell your health care provider if you have any of these side effects that bother you.

  • Bad taste in your mouth or bad breath
  • Heartburn
  • Nausea, upset stomach, or diarrhea
  • Headache
  • Sweat that smells bad

There may be other side effects of omega-3 supplements that are not listed here. Contact your health care provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088 (800-332-1088). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of omega-3 supplements?

While less common, the most serious side effects of omega-3 supplements are described below, along with what to do if they happen.

Severe Allergic Reactions. Omega-3 supplements may cause allergic reactions, which can be serious. Stop taking omega-3 supplements and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching or skin rash
  • Bumps on the skin called hives, which can be red, pink, white, or brown depending on your skin tone
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Warnings & Precautions

Who should not use omega-3 supplements?

Allergies to Ingredients. People who are allergic to any of the following should not take omega-3 supplements.

  • Alpha-linolenic acid (ALA)
  • Docosahexaenoic acid (DHA)
  • Eicosapentaenoic acid (EPA)
  • Fish oil
  • Krill oil
  • Magna Omega-3
  • Oslomega
  • Ultimate Omega
  • Any of the ingredients in the specific product

Your pharmacist can tell you all of the ingredients in the specific omega-3 supplement products they stock.

What should I know about omega-3 supplements before using one?

Read and follow the instructions that come with the product or take it as recommended by your health care provider.

Keep omega-3 supplements out of the reach of children.

If you are taking a liquid omega-3 supplement, use an accurate measuring device to measure your dose. A household spoon is not an accurate measuring device and may cause you to take the wrong dose. Ask your pharmacist what measuring device to use.

What should I tell my health care provider before using omega-3 supplements?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them know if omega-3 is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions. Tell your health care provider if you have any of the following.

Food Allergy. Omega-3 supplements may be made from fish or krill. You may be at risk of an allergic reaction to this medicine if you are allergic to fish or shellfish such as shrimp, crab, lobster, oysters, or scallops. Before taking an omega-3 supplement, tell your health care provider if you are allergic or think that you may be allergic to either fish or shellfish.  

Other Medicines and Supplements. Omega-3 supplements may interact with other medicines and supplements. Before taking an omega-3 supplement, tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Pregnancy. Tell your health care provider if you are pregnant or plan to become pregnant. Your health care provider will let you know if you should take omega-3 supplements while you are pregnant or trying to get pregnant.

Breastfeeding. Omega-3 supplements pass into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed. Your health care provider will let you know if you should take omega-3 supplements while breastfeeding.

Interactions

Do omega-3 supplements interact with foods or drinks?

There are no known interactions between omega-3 supplements and foods or drinks. You should take most omega-3 supplements with food.

It is unknown if drinking alcohol will affect omega-3 supplements.

Do omega-3 supplements interact with other medicines (drug interactions)?

Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before taking an omega-3 supplement.

  • A blood thinner, which is a medicine used to treat or prevent blood clots
  • An antiplatelet medicine, such as aspirin/dipyridamole, cilostazol, clopidogrel (Plavix), or ticagrelor (Brilinta), which is a medicine used to prevent blood clots

This may not be a complete list of medicines that can interact with omega-3 supplements. Always check with your health care provider.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much omega-3 supplements?

If you or someone else has used too much omega-3 supplements, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of omega-3 supplements?

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 only take the next dose. Do not take double or extra doses.