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Safety

The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

Allergies

Avoid with a known allergy or hypersensitivity to flaxseed ( Linum usitatissimum ), flaxseed oil, its constituents, or any other members of the Linaceae plant family. Hypersensitivity reactions to flaxseed following occupational exposure have been reported. Diarrhea; intestinal and abdominal pain; itching, including itchy palms and soles and itchy, weeping eyes; hives; malaise; nasal obstruction; nausea; shortness of breath; sneezing; vomiting; and watery discharge have been reported.

Side Effects and Warnings

Flaxseed may cause gastrointestinal symptoms, headache, "heart problems," hives, increased red blood cell counts, increased risk of prostate cancer, intestinal obstruction, mania or hypomania (in bipolar patients), prolonged luteal phases, rapid breathing, respiratory disease (in flax farmers), vomiting, and weight gain or weight loss. An overdose of flaxseed or flaxseed oil may result in weakness, unstable gait, paralysis, or seizures.

Raw flaxseed or flaxseed plant may increase blood levels of cyanide, a toxic chemical.

Flaxseed may cause low blood pressure. Caution is advised in patients with blood pressure disorders and those taking drugs, herbs, or supplements that affect blood pressure.

Based on the available evidence, flaxseed, which contains alpha-linolenic acid (ALA), should be avoided in patients with prostate cancer or those at risk for prostate cancer.

Use flaxseed and flaxseed oil cautiously in patients with elevated triglycerides, as these agents may raise or lower triglyceride levels.

Flaxseed may increase the risk of bleeding and bleeding time. Caution is advised in patients with bleeding disorders or those taking drugs, herbs, or supplements that may increase the risk of bleeding. Dosing adjustments may be necessary.

Flaxseed may lower blood sugar levels. Caution is advised in patients with diabetes or low blood sugar, and in those taking drugs, herbs, or supplements that affect blood sugar. Blood glucose levels may need to be monitored by a qualified healthcare professional, including a pharmacist. Medication adjustments may be necessary.

Use cautiously in patients using laxatives, as flaxseed, particularly at higher doses (more than 30 grams daily), caused loose stools; theoretically, concurrent use may increase the risk of diarrhea.

Use cautiously in patients using furosemide or ketoprofen, as flaxseed decreased the absorption of these drugs.

Because flaxseed contains estrogen-like chemicals, the effects of other agents believed to have estrogen-like properties may be altered.

Use flaxseed (not flaxseed oil) cautiously in women with hormone-sensitive conditions, due to its possible estrogenic properties.

Avoid consumption of immature flaxseed seedpods, as they may be poisonous.

Avoid topical flaxseed on open wounds or abraded surfaces.

Avoid flaxseed (not flaxseed oil) in patients with esophageal stricture, ileus, gastrointestinal stricture, or bowel obstruction. Ingestion of flaxseed without adequate fluids may precipitate bowel obstruction.

Avoid in patients with acute or chronic diarrhea, irritable bowel disease, diverticulitis (small, bulging sacs or pouches of the inner lining of the intestine that become inflamed or infected), or inflammatory bowel disease, due to the potential laxative effect of flaxseed.

Some natural medicine textbooks advise caution in patients with hypothyroidism, although scant clinical data exist in this area.

Avoid in pregnant or breastfeeding women, due to a lack of available scientific evidence and safety information.

Avoid with a known allergy or hypersensitivity to flaxseed ( Linum usitatissimum ), flaxseed oil, their constituents, or any other members of the Linaceae plant family. Hypersensitivity reactions to flaxseed following occupational exposure have been reported. Diarrhea; intense general malaise; intestinal and abdominal pain; itching, including itchy palms and soles and itchy, weeping eyes; hives; nasal obstruction; nausea; shortness of breath; sneezing; vomiting; and watery discharge have been reported.

Pregnancy and Breastfeeding

Avoid in pregnant or breastfeeding women, due to a lack of available scientific evidence and safety information.

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