Is Fish Oil Harmful?
Many people may wonder if it is harmful to take fish oil. Although fish oil appears to be beneficial for several uses, there are some risks associated with the supplement. For example, you should talk to your healthcare provider prior to taking fish oil if you have certain medical conditions, such as diabetes, bipolar disorder, or a bleeding disorder. Fish oil can make some of these conditions worse.
Fish oil is a popular dietary supplement, used for treating high triglycerides and several other conditions. You should talk with your healthcare provider prior to taking fish oil if you have:
- A bleeding disorder
- Bipolar disorder
- Familial adenomatous polyposis, a genetic condition involving colon polyps
- An implanted heart defibrillator
- A weakened immune system, often due to cancer, HIV, or AIDS
- Any allergies, including allergies to foods (especially fish), dyes, or preservatives.
Also, let your healthcare provider know if you are:
- Pregnant or thinking of becoming pregnant
Make sure to tell your healthcare provider about any other medicines you are taking, including prescription and non-prescription medicines, vitamins, and herbal supplements.
Some of the warnings and precautions to be aware of concerning the safety of fish oil include the following:
- There is some concern that fish oil supplements may contain toxins, such as heavy metals (like mercury) or dioxin, although it seems that taking fish oil supplements may actually be safer than eating fish in this regard. It is a good idea to look for a fish oil product that has been purified and tested for these toxins, and is made by a reputable manufacturer.
It is a good sign if a manufacturer abides by the rules of Good Manufacturing Practices (GMP) for drugs. It is also a good sign if a product has the United States Pharmacopoeia (USP) seal, which means that the product has been independently tested and shown to contain the correct ingredients in the amounts listed on the label. Your pharmacist is a good resource for information about which manufacturers are the most reputable.
- A high fish oil dosage may cause high blood sugar (hyperglycemia) in people with diabetes. If you have diabetes, check with your healthcare provider before taking fish oil supplements. You may need to monitor your blood sugar more closely, and your healthcare provider may need to adjust the dose of your diabetes medication.
- People with familial adenomatous polyposis have a high risk for colon cancer, and there is some concern that fish oil supplements can make this risk even higher. Some healthcare providers recommend that people with this condition avoid fish oil supplements.
- Fish oil can "thin" the blood, preventing blood platelets from sticking together (an important step in blood clotting). If you have a bleeding disorder, do not take fish oil without checking with your healthcare provider.
- Although fish oil may be beneficial for depression symptoms in people with bipolar disorder, it may also increase the risk of mania symptoms. If you have bipolar disorder, do not take fish oil without your healthcare provider's approval and supervision.
- Some studies show that fish oil may increase the risk of dangerous arrhythmias in people with implanted heart defibrillators, while other studies did not find a risk. Until more information is available, it may be a good idea to avoid fish oil if you have an implanted defibrillator.
- High doses of fish oil may suppress the immune system. If you already have a weakened immune system, fish oil may further increase your risk of infections or other problems.
- Fish oil can interact with some medications (see Fish Oil Drug Interactions for more information).
- Fish oil that is free of toxins is probably safe for pregnant or breastfeeding women (see Pregnancy and Fish Oil and Fish Oil and Breastfeeding). However, pregnant and breastfeeding women should avoid any fish or fish oil that may contain toxins.
- Some people who are allergic to fish or shellfish may also be allergic to fish oil supplements.