Flaxseed oil side effects are minimal when the supplement is taken in small doses, although there are potentially harmful side effects when it's taken in larger doses. The typical flaxseed side effects include diarrhea and allergic reactions. Some studies suggest flaxseed oil may increase the risk of prostate cancer in men.
Coming from the plant Linum usitatissimum, flaxseed is native to the Mediterranean region and India. The oil, extracted from the flaxseed, is commonly used as a health supplement, although it's also incorporated in many foods. Promoters of flaxseed oil often claim it has various health benefits, including helping with digestion, reducing inflammation, controlling cholesterol, and protecting against rheumatoid arthritis.
Many scientific studies show little if any benefit from taking flaxseed oil, however. Other purported health benefits of flaxseed oil include a reduction in symptoms for attention deficit hyperactivity disorder (ADHD), a decrease in the risk of heart disease, a reduction in the risk of breast cancer, and a lowering of the blood's fatty acids. There is conclusive evidence that suggests flaxseed oil does not lower the blood's fatty acids, but the jury is still out on the other benefits as the studies are inconclusive.
One of the most common flaxseed oil side effects is diarrhea, particularly when the oil is consumed in large quantities. Most of the flaxseed oil side effects occur when flaxseed oil is taken by people with particular conditions. For example, the flaxseed oil side effects for pregnant women can potentially be dangerous. Taking flaxseed oil during the second and third trimester can increase the risk of premature birth. For this reason, pregnant women are advised to avoid flaxseed oil.
Flaxseed oil may also increase the risk of bleeding, particularly with patients with bleeding disorders, or patients who've recently had surgery. Some experts recommend that flaxseed oil not be taken two weeks before or after surgery. It's best to avoid the supplement while breastfeeding because the oil's side effects for breast-feeding mothers is unknown.