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Flaxseed Oil

What is flaxseed oil?

Flaxseed oil (also called flax oil) is derived from flax plant seeds and contains high levels of alpha-linolenic acid (ALA), an omega-3 fatty acid.

Omega-3 fatty acids have been shown to have anti-inflammatory effects in the body. Flaxseed oil is used as a dietary supplement to treat inflammatory conditions such as allergies, arthritis, kidney disease, heart disease, diabetes, epilepsy, and some types of cancer in cats, dogs, and other animals.

In addition to omega-3 fatty acids, ground flaxseed also contains dietary fiber, which can have other benefits, such as intestinal health and reduced constipation. It can be used in both dogs and cats, although effectiveness may be questionable in cats.

The U.S. Food and Drug Administration (FDA) does not review non-drug health products (e.g., herbals, nutraceuticals, shampoos, and other supplements) for safety or effectiveness before they are sold to the public. Manufacturers of non-drug health products must ensure their products are safe and labeled accurately. The FDA requires that these non-pharmaceuticals contain a disclaimer that says, “This product is not intended to diagnose, treat, cure or prevent any disease.” Health Canada licenses “veterinary health products” after reviewing safety, efficacy, and manufacturing information provided by the manufacturer. These products are not tested by Health Canada.

Your veterinarian is the best source of information about the safety of non-drug health products in pets. Just because a product is natural does not mean it is safe. All medicines and medicinal plants are potentially toxic if used inappropriately or given at high doses. Supplements can also have side effects, like pharmaceuticals. Few supplements and herbs have been subjected to rigorous scientific trials to determine their efficacy.

Although the information in this handout may be helpful, it also may be incomplete and may not represent the full range of effects the supplement could have on your pet.

How is flaxseed oil given?

  • Flaxseed oil comes in liquid and capsule forms.
  • All forms are given orally (by mouth).
  • Oral forms may be given with or without food.
  • Measure liquid doses carefully.
  • Follow your veterinarian’s instructions on administering this medication and give it for the entire time prescribed by your veterinarian, even if your pet is feeling better.

This medication may take several weeks before full effects are seen, but outward improvements may be noticeable after a few days.

What if I miss giving my pet the supplement?

If you miss a dose, give it as soon as you remember. However, if it is almost time for the next scheduled dose, skip the missed dose and resume the regular dosing schedule. Do not give the pet two doses at once.

Are there any potential side effects?

Flaxseed oil may cause the following side effects:

  • Mild gastrointestinal upset (gas, soft stools)
  • Delayed wound healing
  • Oily coat or mild skin flaking

Serious adverse reactions may occur. If any of the following signs develop, stop giving flaxseed oil and contact your veterinarian immediately:

  • An allergic reaction such as irregular breathing, rash, fever, puffiness and swelling around the face
  • Consistent, severe stomach upset
  • Pancreatitis

Drug sensitivities can develop over time with repeated exposure. Your pet may have no reaction after the first few doses, but may develop a sensitivity later. It is important to watch for signs of an allergic reaction over the entire course of treatment.

Other side effects may occur. If you notice anything unusual, contact your veterinarian immediately. This long-acting medication should stop working within several weeks, though effects may last longer in pets with liver and/or kidney disease.

Are there any risk factors for this supplement?

DO NOT USE flaxseed oil in:

  • Pets that are allergic to any component of the medication

USE WITH CAUTION in:

  • Pets that are taking anticoagulant medications
  • Pets that need high doses of flaxseed oil to see clinical effects

Are there any drug interactions I should be aware of?

The following medications should be used with caution when given with flaxseed oil:

  • Anticoagulants (e.g. heparin, warfarin)
  • Blood pressure medications
  • Insulin and other antidiabetic agents

Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking before starting any new treatment.

Is any monitoring needed with this supplement?

  • Follow your veterinarian’s directions for follow-up visits and diagnostics.
  • At home, monitor for any abnormal changes. If these occur, discontinue the medication and contact your veterinarian.

How do I store flaxseed oil?

  • Store the medication according to the manufacturer’s directions.
  • Protect from light, heat, and moisture.
  • Keep medication out of reach of children and pets.

What should I do in case of emergency?

If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility. Be prepared to provide information about the product and your pet’s weight and symptoms. Report any adverse effects to the FDA or Health Canada.

© Copyright 2025 LifeLearn Inc. Used and/or modified with permission under license. This content written by LifeLearn Animal Health (LifeLearn Inc.) is licensed to this practice for the personal use of our clients. Any copying, printing or further distribution is prohibited without the express written consent of LifeLearn. This content does not contain all available information for any referenced medications and has not been reviewed by the FDA Center for Veterinary Medicine, or Health Canada Veterinary Drugs Directorate. This content may help answer commonly asked questions, but is not a substitute for medical advice, or a proper consultation and/or clinical examination of your pet by a veterinarian. Please contact your veterinarian if you have any questions or concerns about your pet’s health. Last updated on Oct 31, 2025.