What Should You Not Take with Flaxseed Oil?

December 22, 2025 •

4 min read

Studies indicate that flaxseed and its oil can reduce blood pressure and blood sugar, highlighting the importance of understanding potential medication interactions. Knowing what you should not take with flaxseed oil is essential for avoiding complications like excessive bleeding, dangerously low blood pressure, or altered medication efficacy.

Quick Summary

Flaxseed oil interacts negatively with certain medications. These can include blood thinners, diabetic drugs, and blood pressure medication, causing excess bleeding, low blood sugar, or hypotension.

Key Points

Blood Thinners: Avoid combining flaxseed oil with anticoagulants like warfarin, aspirin, or ibuprofen, as this can increase the risk of bleeding and bruising.
Diabetic Medications: Never take flaxseed oil with insulin or other diabetes medications without medical supervision, as it can cause dangerously low blood sugar (hypoglycemia).
Blood Pressure Drugs: Do not use flaxseed oil with blood pressure-lowering medications, as the combination can lead to hypotension (excessively low blood pressure).
Hormone Therapy: Be cautious if taking estrogen-based medications, birth control, or have hormone-sensitive conditions, as flaxseed oil's phytoestrogens can interfere.
Oral Medication Absorption: To ensure proper absorption, take other oral medications at least 1-2 hours away from flaxseed oil.
High-Heat Cooking: Do not use flaxseed oil for cooking, as its low smoke point causes it to break down and create harmful compounds.
Pre-Surgery: Discontinue flaxseed oil at least two weeks before any scheduled surgery to minimize the risk of bleeding complications.

Flaxseed oil is a popular dietary supplement, prized for its high content of alpha-linolenic acid (ALA), an omega-3 fatty acid. Its health benefits, such as lowering cholesterol and supporting heart health, are widely recognized. However, as with any supplement, understanding its potential to interact with other medications is critical for safety and efficacy. Certain prescription drugs, over-the-counter medicines, and other health supplements should not be taken concurrently with flaxseed oil due to the risk of adverse health effects. Always consult a healthcare professional before adding any new supplement to your routine, especially if you are managing a pre-existing medical condition.

Medications That Slow Blood Clotting

One of the most significant concerns regarding flaxseed oil interactions is its effect on blood clotting. The omega-3 fatty acids in flaxseed oil have natural blood-thinning properties, which can be problematic when combined with other anticoagulant or antiplatelet medications. Taking both can significantly increase the risk of bruising, bleeding, and hemorrhaging.

This includes a wide range of medications such as:

Warfarin (Coumadin): A powerful anticoagulant.
Aspirin: A common antiplatelet used to prevent heart attacks.
Clopidogrel (Plavix): Another antiplatelet medication.
Nonsteroidal Anti-Inflammatory Drugs (NSAIDs): These include ibuprofen (Advil, Motrin) and naproxen (Aleve).

Patients on these medications are often advised to stop taking flaxseed oil several weeks before any scheduled surgery to minimize bleeding risk.

Diabetes Medications

Flaxseed oil may help lower blood sugar levels, a beneficial effect for some. However, this effect can be dangerous for individuals already taking medication to control their blood sugar. Combining flaxseed oil with antidiabetic drugs can lead to hypoglycemia, a condition where blood sugar drops to dangerously low levels.

Examples of interacting diabetic medications include:

Insulin injections: Taken to manage blood sugar.
Metformin (Glucophage): A commonly prescribed oral diabetes medication.
Glipizide (Glucotrol): An oral medication that helps the body produce more insulin.

Anyone with diabetes should monitor their blood sugar closely and consult their doctor before adding flaxseed oil to their diet.

Blood Pressure Medications

Just as it can affect blood sugar, flaxseed oil can also lower blood pressure. For those with hypertension already on medication, this can lead to a condition known as hypotension, where blood pressure falls too low. Symptoms of low blood pressure can include dizziness, lightheadedness, and fainting.

Interacting blood pressure medications include:

ACE inhibitors: Such as Captopril (Capoten) or Enalapril (Vasotec).
Angiotensin receptor blockers (ARBs): Such as Losartan (Cozaar) or Valsartan (Diovan).
Calcium channel blockers: Such as Amlodipine (Norvasc).

Hormone-Sensitive Medications

Flaxseed contains phytoestrogens, plant-based compounds that can mimic the hormone estrogen in the body. This property can interfere with medications that affect hormone levels. Individuals with hormone-sensitive conditions or those on hormone therapy must be cautious.

This includes:

Estrogen replacement therapy (HRT): For menopausal symptoms.
Birth control pills: May become less effective.
Tamoxifen: A medication used in the treatment of breast cancer.

Timing for Oral Medications

Beyond direct interactions, flaxseed oil can also affect the absorption of other medications. To ensure the body properly absorbs all your necessary medicines, it is advisable to take other oral medications at least one to two hours after consuming flaxseed oil. This separation is especially important for medications where precise dosage and absorption are critical.

Flaxseed Oil vs. Fish Oil Interactions


Feature	Flaxseed Oil	Fish Oil (Omega-3)	Key Interaction Difference
Primary Omega-3	Alpha-Linolenic Acid (ALA)	Eicosapentaenoic Acid (EPA) & Docosahexaenoic Acid (DHA)	EPA and DHA in fish oil are more directly anti-inflammatory, whereas ALA from flaxseed must be converted in the body.
Blood Thinning	Can increase bleeding risk, especially with medications like warfarin.	Can also increase bleeding risk, especially at higher doses.	Both can thin the blood, but medical guidance is needed for both if on anticoagulants.
Cooking Suitability	Not suitable for high heat cooking due to low smoke point.	Some fish oils are refined for high heat, but most are better consumed unheated or via supplements.	Flaxseed oil is very prone to oxidation from heat, which makes it unsuitable for cooking.
Estrogen-like Effects	Contains lignans, which are phytoestrogens and can interfere with hormone therapies.	No significant phytoestrogen content.	Flaxseed oil's hormonal impact is a unique consideration not typically associated with fish oil.

How to Use Flaxseed Oil Safely

To maximize the benefits of flaxseed oil while minimizing risks, consider these safety guidelines:

Consult a professional: Before adding flaxseed oil to your diet, have a detailed discussion with your doctor, pharmacist, or a registered dietitian, especially if you take any prescription medications.
Time it right: If your doctor approves, time the intake of flaxseed oil and other oral medications at least 1-2 hours apart to avoid malabsorption.
Stop before surgery: Inform your surgical team if you are taking flaxseed oil, and plan to stop use at least two weeks before any procedure to minimize bleeding risks.
Never cook with it: Due to its low smoke point, only use flaxseed oil for cold applications like dressings, dips, or adding to smoothies. High heat can destroy the beneficial fatty acids and create harmful free radicals.
Check the expiration: Store flaxseed oil in a cool, dark place and check the expiration date. Rancid oil can lead to inflammation and other issues.

Conclusion

While flaxseed oil offers numerous health benefits, its interaction with various medications makes careful consideration essential. Key interactions involve medications for blood thinning, diabetes, and high blood pressure, where flaxseed oil's natural effects can dangerously amplify or interfere with drug action. The phytoestrogens in flaxseed oil also necessitate caution for those on hormone-related therapies. By consulting a healthcare provider and being mindful of these potential interactions, you can safely enjoy the advantages of flaxseed oil. For more information on drug interactions with flaxseed oil, consult reliable health resources like the Mayo Clinic's guide on supplements.

Frequently Asked Questions

No, you should not take flaxseed oil with blood thinners like warfarin, clopidogrel, or aspirin. Flaxseed oil has natural blood-thinning properties that, when combined with these medications, can significantly increase the risk of bleeding and bruising.

If you have diabetes and take medication, you should consult your doctor before using flaxseed oil. Since flaxseed oil can lower blood sugar, combining it with diabetic medications such as insulin or metformin can cause dangerously low blood sugar levels (hypoglycemia).

Flaxseed oil can lower blood pressure. Taking it with antihypertensive drugs can cause blood pressure to drop too low, leading to hypotension with symptoms like dizziness or fainting.

Yes, flaxseed contains phytoestrogens that can mimic the effects of estrogen in the body. This can potentially reduce the effectiveness of hormone therapies like birth control pills and estrogen replacement therapy.

To avoid interfering with the absorption of other oral medications, you should take them at least one to two hours apart from consuming flaxseed oil.

No, you should not cook with flaxseed oil. It has a very low smoke point and can become rancid and produce harmful free radicals when exposed to high heat.

Individuals who are pregnant, breastfeeding, or have hormone-sensitive conditions like endometriosis or breast cancer should be cautious and speak with a doctor before using flaxseed oil. It is also not recommended for children.

Both flaxseed oil and fish oil can have blood-thinning effects, but flaxseed oil also contains phytoestrogens (lignans) that can affect hormones, an interaction not typically seen with fish oil.