Fish Oil
Over-the-counterWhat is Fish Oil?
Fish oil is a dietary supplement made from the tissues of oily fish like salmon, mackerel, and sardines. It contains omega-3 fatty acids, specifically EPA and DHA, which are essential fats your body cannot make on its own. These nutrients support heart health, brain function, and reduce inflammation throughout your body.
Millions of Americans take fish oil supplements to get enough omega-3 fatty acids in their diet. Most people do not eat enough fatty fish to meet recommended intake levels. Fish oil supplements provide a concentrated source of these beneficial fats in convenient capsule or liquid form.
Fish oil is available without a prescription at most pharmacies and health stores. Quality can vary between brands, so look for products that have been tested by third-party labs. Some prescription-strength fish oil products contain higher doses of EPA and DHA for specific medical conditions.
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Common uses
- Supporting heart health and cardiovascular function
- Reducing triglyceride levels in the blood
- Supporting brain health and cognitive function
- Reducing inflammation in joints and throughout the body
- Supporting eye health and vision
- Promoting healthy skin and hair
- Supporting mood and mental health
- Helping with fetal brain development during pregnancy
How it works
Fish oil works by providing your body with EPA and DHA, two types of omega-3 fatty acids. These fats become part of your cell membranes and help cells function properly. They also reduce inflammation by competing with omega-6 fatty acids, which can promote inflammation when out of balance.
For heart health, omega-3s help lower triglycerides by reducing the liver's production of these fats. They may also help prevent irregular heartbeats and reduce blood clotting. In the brain, DHA makes up a large portion of brain tissue and supports communication between brain cells.
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Dosage information
Most fish oil supplements contain 300 to 1000 mg of combined EPA and DHA per capsule. A typical daily dose ranges from 250 to 3000 mg of combined omega-3s, depending on your health goals. For general health maintenance, 250 to 500 mg daily is common. Higher doses of 2000 to 3000 mg may be used for reducing high triglycerides. Always check the label for actual EPA and DHA content, not just total fish oil. Start with a lower dose and take with meals to reduce fishy aftertaste or stomach upset.
Side effects
- Fishy aftertaste or burps
- Bad breath with fishy odor
- Upset stomach or nausea
- Diarrhea or loose stools
- Heartburn or acid reflux
- Headache
Serious side effects are rare but can include increased bleeding or bruising, especially at higher doses. Fish oil can thin your blood, which may cause problems if you have bleeding disorders or take blood thinners. Stop taking fish oil and contact your doctor if you notice unusual bleeding, severe stomach pain, or allergic reactions like rash or difficulty breathing.
Drug interactions
- Blood thinners like warfarin, aspirin, or clopidogrel may increase bleeding risk when combined with fish oil
- Blood pressure medications may have added effects, potentially lowering blood pressure too much
- Contraceptive drugs may have reduced effectiveness with high-dose fish oil
- Orlistat may reduce absorption of omega-3 fatty acids
- People with fish or shellfish allergies should use caution or avoid fish oil
- Those scheduled for surgery should stop fish oil 2 weeks before due to bleeding risk
Blood test monitoring
If you take fish oil regularly, especially at higher doses, you should monitor your triglyceride levels to see if the supplement is working. A lipid panel blood test measures triglycerides along with cholesterol levels. Testing your omega-3 index can show whether you have healthy levels of EPA and DHA in your blood. This helps you know if your current dose is right for you. Rite Aid offers blood testing services that measure triglycerides and omega-3 levels, along with 200 other biomarkers. Getting tested twice per year helps you track changes and adjust your supplement routine as needed.
Related blood tests
Taking Fish Oil? Monitor your levels.
- Track how your body responds
- Catch side effects early with blood work
- Share results with your doctor
Frequently asked questions
No, fish oil supplements are available over the counter at pharmacies and health stores. You do not need a prescription for standard fish oil products. However, some high-dose prescription fish oil medications exist for treating very high triglycerides. These prescription versions require a doctor's order.
You may notice some benefits like reduced joint stiffness within 2 to 3 weeks. However, changes to triglyceride levels typically take 4 to 6 weeks of consistent use. For brain and heart benefits, you may need 2 to 3 months to see meaningful results. Fish oil works best when taken daily over the long term.
Take fish oil with meals to improve absorption and reduce side effects like fishy burps or stomach upset. The fat in your food helps your body absorb the omega-3 fatty acids better. Taking it with your largest meal of the day is often the best option.
People with fish allergies should be cautious with fish oil supplements. Some allergic reactions have been reported, though the purified oil contains less protein than fish meat. Talk to your doctor before taking fish oil if you have a known fish allergy. Algae-based omega-3 supplements may be a safer alternative for people with fish allergies.
You should monitor your triglyceride levels to see if fish oil is helping lower them. An omega-3 index test measures the amount of EPA and DHA in your red blood cells. This shows whether you are taking enough fish oil to reach healthy levels. Testing twice per year helps you track your progress and adjust your dose.
Fish oil is generally considered safe during pregnancy and may benefit fetal brain development. DHA is particularly important for the baby's brain and eye development. However, you should choose supplements that are tested for mercury and other contaminants. Always talk to your doctor before taking any supplement during pregnancy.
Fish oil may lower blood pressure slightly, which could add to the effects of blood pressure medications. This is usually not dangerous but may require dose adjustments. Tell your doctor you are taking fish oil so they can monitor your blood pressure. Most people can safely take both together.
EPA and DHA are both omega-3 fatty acids but have different roles in your body. EPA primarily helps reduce inflammation and supports heart health. DHA is more concentrated in the brain and eyes and supports cognitive function. Most fish oil supplements contain both, though the ratio varies between products.
Yes, you should stop taking fish oil at least 2 weeks before scheduled surgery. Fish oil can thin your blood and increase bleeding risk during and after surgical procedures. Tell your surgeon and anesthesiologist about all supplements you take. You can usually resume fish oil after your doctor confirms healing is progressing well.
Look for products tested by independent labs like USP, NSF, or IFOS for purity and potency. Check the label for the actual amounts of EPA and DHA, not just total fish oil. Choose supplements that are molecularly distilled or tested for mercury, PCBs, and other contaminants. Enteric-coated capsules may reduce fishy aftertaste.