Omega Fish Oil Side Effects

The federal government recognizes that consuming omega-3 fatty acids might reduce the risk of heart disease. Omega-3 fatty acids also might positively influence diabetes, lupus, osteoporosis, depression, psychological disorders, skin conditions, eye health, asthma and certain cancers, according to the University of Maryland Medical Center (UMMC). Omega-3 fatty acids are concentrated in fish oil and available through foods and supplements. Supplements can cause multiple side effects.

Bleeding Risk

Individuals who bruise easily, have a bleeding disorder or who take medications to thin blood should limit or avoid omega-3 fish oil supplements. The National Institutes of Health (NIH) says that omega-3 fatty acids have a bleeding risk, and large doses can cause nosebleeds and bloody urine. Fish oil might prolong bleeding times, prevent the formation of blood clots and break down existing blood clots. Blood-thinning medications such as aspirin, warfarin (Coumadin) and Plavix can negatively interact with fish oil supplements.

Gastrointestinal Side Effects

The most common deterrents to taking fish oil include fishy aftertaste, intestinal discomfort and nausea, according to the American Heart Association (AHA). Other intestinal side effects include diarrhea, burping, heartburn and indigestion, bloating and abdominal pain. The NIH recommends taking fish oil supplements with food to minimize side effects and starting with a low dose that increases gradually.

Decreased Blood Pressure

According to the NIH, numerous studies have shown the blood pressure-lowering capabilities of omega-3 fatty acids. This can benefit individuals with high blood pressure (hypertension) but is dangerous for people with existing low blood pressure (hypotension). Individuals taking medications to lower blood pressure should consult a physician before taking fish oil supplements.

Increased Blood Glucose

The UMMC says fish oil supplements can increase blood glucose (blood sugar) and interact with diabetic medications like glipizide, glyburide, metformin and insulin. As of early 2010, there is no evidence to suggest that fish oil supplements have long-term effects on blood glucose, but diabetics should consult a physician before taking fish oil supplements.

Mercury Toxicity

Consuming fish to get omega-3s from fish oil is healthy, but some fish are high in mercury, a dangerous contaminant for pregnant women and children. Federal guidelines encourage pregnant women and children to eat low-mercury fish to benefit from omega-3 fatty acids. Low-mercury fish include salmon, halibut, canned tuna, mahi-mahi, cod and snapper. Shark, mackerel, swordfish and tilefish should be avoided because they are extremely high in mercury. According to the NIH, fish oil supplements do not contain mercury and are safe for pregnant women.

Additional Side Effects

Individuals with allergies or sensitivities to fish should not take omega-3 fish oil supplements. Other food sources of omega-3 fatty acids include walnuts, flaxseed and vegetable oils. In rare cases, omega-3 fish oil supplements have caused rash, liver function abnormalities and psychological disorders in people who suffer from depression and bipolar disorders.