Flaxseed oil provides beneficial fatty acids, such as alpha-linolenic acid, that appear to decrease inflammation. Flaxseed oil is used for many health conditions, but available scientific evidence has not verified most of these uses, according to MedlinePlus, a website from the U.S. National Institutes of Health. MedlinePlus says flaxseed oil is likely safe for most adults when consumed in appropriate amounts on a short-term basis.
Digestive Effects
Large doses of flaxseed oil, such as 30 g per day and more, can cause gastrointestinal effects, according to MedlinePlus. Some people have reported loose stools and diarrhea.
Bleeding Risk
Flaxseed oil has blood-thinning effects, as it slows blood clotting. This may raise the risk of severe bleeding in people with bleeding disorders. MedlinePlus suggests talking with your health care provider if you have a bleeding disorder and are considering consuming flaxseed oil. In addition, ingesting flaxseed oil could elevate the risk of bleeding during and after surgery, so stop doing so at least two weeks before any scheduled operation.
Interactions That Increase Bleeding
Consuming flaxseed oil when you also take medications that slow clotting is another risk factor for increased bleeding, as well as for bruising. Some medications with blood-thinning effects include aspirin, ibuprofen, naproxen, clopidogrel, heparin and warfarin. Certain herbs and other supplements also slow blood clotting, such as garlic, ginger and Ginkgo biloba. EMedTV says to watch for easy bruising and cuts that continue bleeding longer than usual. Signs of gastrointestinal bleeding, such as black tarry stools, bright red blood in the stool and vomiting blood, require immediate medical attention.
Interactions that Lower Blood Pressure
Flaxseed oil may reduce blood pressure. If you take any medication to reduce blood pressure, the combination creates a risk of blood pressure dropping too low, according to MedlinePlus. In addition, some herbs and supplements also lower blood pressure and could interact with flaxseed oil. Examples include cat's claw, stinging nettle, coenzyme Q-10, fish oil and the amino acid L-arginine.
Pregnancy Considerations
Pregnant women should not ingest flaxseed oil. The oil may increase the chance of premature birth when taken during the last six months of pregnancy, according to MedlinePlus.
Allergic Reaction
It is possible to have a severe allergic reaction to flaxseed oil. Do not ingest this oil if you are allergic to flaxseed or its oil, or to any other members of the Linum plant genus, advises MayoClinic.com. Signs of an allergic reaction may include a rash, hives, itching, unexplained swelling, wheezing, trouble breathing and difficulty swallowing. An allergic reaction to flaxseed oil calls for immediate medical attention.