Fish oils are generally regarded as highly beneficial, but this does not mean that they are without risks in some circumstances. Salmon oil is derived from the essential fats of salmon, a cold water fish known to naturally contain high levels of omega-3 fatty acids. The oil can be absorbed into the body either by eating salmon meat or by taking salmon oil dietary supplements. In moderate doses, it is considered generally safe for most people. In excess, however, it can cause trouble, and its side effects are more pronounced for people with certain medical problems, particularly blood conditions, heart irregularities, and diabetes.
Eating salmon directly only rarely causes side effects. Most of the time, the side effects are caused when someone uses nutritional supplements. In supplements, oil is extracted from the salmon’s fatty acids and packaged into capsules. The concentration of oil in any given capsule varies by manufacturer, but most of the time, the amount in one to two capsules is about what one would expect to find in a normal portion of salmon meat.
When a person experiences side effects from the oil, it is often because the oil is being consumed in isolation more than anything else. The most common salmon oil side effects are upset stomach and brief nausea, sometimes accompanied by flatulence. Eating crackers or a small meal when taking salmon oil capsules may help prevent this discomfort.
Omega-3 fatty acids are known as “healthy fats,” but consuming them in large quantities can be harmful. In particular, omega-3s have been shown to cause irregular bleeding when consumed in high amounts. Salmon oil has high concentrations of omega-3 fatty acids, and taking large doses over time has been linked to internal bleeding and strokes.
Most government agencies leave nutritional supplements unregulated, which means that there are rarely recommend daily doses or set acceptable use levels for supplements like salmon oil. Most nutritional supplement manufacturers include recommended doses on their products, however, which should be followed to avoid excessive consumption. While there is plenty of international data supporting the benefits of consuming some fish or salmon oil every day, there is no evidence that a large quantity is better than a small one.
More uncommon side effects of salmon oil are seen in conjunction with other conditions. People who have pre-existing blood conditions should talk to a medical professional before beginning a regular regimen of fish oil to avoid inflamed veins or an increased risk of bleeding irregularities. There are also particular side effects often experienced by people with a history of heart trouble and those with diabetes. Some of the compounds in salmon oil have also been known to interact with some prescription medication, particularly cholesterol-lowering drugs and certain steroid treatments. A medical professional or pharmacist will be able to answer specific questions about drug-related salmon oil side effects.
Although uncommon in salmon oil, mercury poisoning is a rare but serious side effect of fish oil generally. Salmon does not have naturally high levels of mercury, but other fish — tuna and mackerel in particular — frequently do. Mercury can cause very serious health concerns when ingested in large doses. Salmon oils that are actually blends of many fish oils carry the most risk of mercury-related side effects.