5 Flaxseed Oil Side Effects and Best Dosage

Dosage Flax Oil While there are many flaxseed oil health benefits, there are also some potential negative effects and it’s important to get the amount of flax oil that you take right.

This page lists the main 5 side effects of flax oil occasionally reported and suggests a dosage method based on slow increase to reduce the chances of a negative reaction.

5 Potential Flaxseed Oil Side Effects

1. Blood Thinning Precautions

The omega-3 fatty acids in flax oil can help make blood platelets less sticky, potentially reducing the chances of a dangerous blood clot forming in our arteries.

This same effect though may amplify the action of blood thinning medications. It is very important to check with your doctor before taking flaxseed oil if you are using prescription drugs like warfarin, clopidogrel or even daily aspirin for blood thinning.

Supplementing at high doses with the oil may increase the risk of bleeding during or after surgery. It is recommended to stop taking flax, or any other omega-3 supplements, two weeks before undergoing major surgery.

2. Diabetes and Blood Sugar Levels

Taking large doses of flaxseed oil may slightly lower blood sugar levels. This would generally be a good thing, but there is some concern that diabetes sufferers taking blood sugar lowering medications at the same time as flax oil could reduce their blood sugar too low.

Once again, consult your doctor and avoid taking the oil at the same time as any important medications, regardless of the health condition.

3. Flaxseed Oil and Pregnancy

There are several reasons why flaxseed oil is more important for women, but it is not generally recommended for pregnant women in their second or third trimester.

This is due to some research suggesting a possible increase in the chance of a premature birth with large doses. While far from proven, it would be best to discuss this with your obstetrician or other healthcare professional before taking it during pregnancy.

Some medical resources also suggest not using flaxseed oil when breast-feeding, though no research is cited for this warning. Perhaps a corresponding warning for excessive amounts of omega-6 fats in the diet would be also be relevant for breastfeeding women.

4. Allergic Reactions 

Very occasionally, allergic reactions to flax oil have been reported that may include rashes, itching and swelling. These instances are considered very rare and have generally not been confirmed to actually be caused by flaxseed itself.

5. Gastrointestinal Problems

Gastrointestinal problems are sometimes associated with flax, though this is usually the high-fiber ground meal, rather than the extracted oil.

Occasionally an upset stomach and diarrhea has been reported with taking 30 grams or more in one dose of flaxseed oil. This is a large amount and probably too much to start with initially.

Below is a method for slowly increasing your dosage to get the maximum benefit while reducing the risk of side effects.

How to Flaxseed Oil for Maximum Benefit

Flax is a powerful supplement and increasing your intake of omega-3 fatty acids and the other nutrients in it can have many health benefits. That said, some people do seem to react badly to large doses of flaxseed oil, especially if they have never had it before.

To minimize the chances of side effects, it is best to start off with a high quality flaxseed oil like this, take just a small amount the first week and increase your daily dose on a weekly basis.

Particularly if your diet has been lacking in omega-3 fats in the past, it will probably be more beneficial to increase your dosage steadily over several weeks, rather than immediately taking your maximum dose.

Taking flaxseed oil in this way gives your body time to adapt to a new omega-3 to omega-6 fat ratio, minimizing the risk of side effects. You can also monitor any positive results from taking the oil and get an idea of your ideal daily intake.

Having flaxseed oil with a meal is usually recommended over having it on an empty stomach. Splitting the dosage between morning and evening is also generally preferred, rather than having it all in one go.

It is also important to use a high-quality oil that is cold pressed and unrefined. There are several of the best of these listed in the page on where to buy flaxseed oil online.

Best Flaxseed Oil Daily Dosage

Week 1

With all this in mind, it can be a good idea to start your first week of flaxseed oil with just 1 gram in the morning with breakfast and 1 gram with your evening meal.

This is only around a quarter of a teaspoon of the liquid oil or usually one flax oil capsule, but check the dosage information on the container.

Week 2

For the following week this amount could be doubled to 4 grams a day. Split into 2 grams with breakfast or lunch and 2 grams with dinner. This is around half a teaspoon or two of these organic flax oil capsules.

Week 3 and Beyond

By the third week you could double this again to a teaspoon or four capsules at around 4 grams per morning and 4 grams in the evening. 8 to 10 grams daily should be a good flaxseed oil dosage in the higher range for most people.

If you wish to increase the amount taken beyond here it would be preferable to add to the total amount by just an extra gram per morning and evening for the subsequent weeks.

Finding the Right Flax Oil Amount for You

If you do experience any side effects from taking flaxseed oil you could either stop immediately and try again from the initial dose, or even just 1 grams a day.

Alternatively, you could cut the amount you take back by half or even a quarter and slowly built up by a gram a week to a level where you are seeing the health benefits of flaxseed oil without any side effects.

Some people report very positive results with 2 tablespoons a day of fresh flax oil like this one I use. That’s around 30 grams. Others have side effects with flaxseed oil at these larger amounts.

By starting a lower dosage and building up the amount of oil you take each week, your body is less likely to have a bad reaction to it. You may also find you are getting good results at 8 to 10 grams per day or even lower and don’t need to go up to the higher flaxseed oil dose.

I hope these flax oil and capsule dosage recommendations and list of flaxseed side effects to be aware of has been helpful. I’d be interested to hear what you think and your own experiences with taking it regularly.

Photo 1 credit with thanks: Healthaliciousness


How about one takes 1 tbs. flaxseed 2-3 times per week? This person being on Warfarin, but, not taking at the same time as Warfarin and again, only having a tbs. a couple times per week, that should not be a problem, correct?

Jim Dillan

Hi Daniella,

That doesn’t seem like a large amount as long as it is not taken anywhere near the medication. It’s still always advisable to consult your practitioner if you’re on important medications.


Do you have to take the oil separately or can you include it in meals and avoid treating it as a medicine?

Jim Dillan

Hi Jennifer,

If you can add it to your meals that would be great but flaxseed oil shouldn’t be heated so on a salad is fine but in baked goods or a frying pan isn’t.

Hope this helps.

James S. Kantor

I have been taking one tablespoon of Barlean’s Organic every day or sometimes every other day, for the last two years. Recently I started taking two tablespoons a day. When I start taking two tablespoon of flax-seed oil I notice an increase in clotting time say after I shave, in one week.

My family doctor said I could go back to my old dose but not to take two tablespoons a day.
I started taking two tablespoons after reading The Healing Power of Flax by Herb Joiner-Bey, ND which is a great book and highly recommend. I would just not take a high dose. I was mixing my flax oil in smoothies, but when I went to two, I was also taking directly by mouth. The recomendation from the book was one tablespoon per 100 pounds of weight.
I am a 55, yo white male, wt 200 lb in general good health. I do have hypertension and hypothyroidism, both treated.

Jim Dillan

Hi James and thanks for the information. Two tablespoons is quite high and a bit of a jump from one straight to two. I prefer to see doses go up more slowly, perhaps at a quarter of a tablespoon at a time, though it sounds best to take your doctor’s advice if he thinks it may interfere with medication.

All the best.


My eye doctor said I should take flaxseed for dry eye. I bought Barlean’s 1200 mg capsules. Directions said 3-9 capsules. I took 3 capsules. Within 24 hours I developed itching all along my backside from upper thigh up to my waist. Wonder if taking 3 at once for my first time could result in this?

Jim Dillan

Hi there,

It suggested to work up to the higher doses with flaxseed oil and 9 1000mg capsules would certainly be too much for some people to start. That you had such a reaction with 3 could mean you are a bit sensitive to them.

I’d suggest starting with one a day with food for the first week. If this is well tolerated move up to 2 and so on. If you have a reaction move down in the dosage and then try again after a week.

Hope this helps,



Is it better to take flaxseed oil with lignans or regular? Thanks.

Jim Dillan

Hi Martha,

I tend to think with lignans is better for women as described in this article https://superfoodprofiles.com/flaxseed-oil-women

All the best,



Hi Jim,
I went thru all the post above seems to a lot helpfull,I stay in India the climate here is hot n humid are the same suggestions usefull here also.
How much dosage of grounded flax seeds can be taken along with flax seed oil as suggested by u.
Hope to hear soon from you.


what effects does taking it as cold pressed pills have on ones body when its their very first time? Ive been taking it for 4 days now and i find im unable to tell now whether im feeling hungry or not, n if i am hungry i no longer just know what it is i want to eat, i feel somewhat drained also. Although i feel these ways it doesnt feel any alarming, i just need to understand whether its my body adapting or what. Please get back to me.

Jim Dillan

Hi there,

If you are having such strong effects that you are sure is from the flax oil then perhaps the initial dosage is too high. I’d consider halving the dosage to a level where you have no side effect then slowly building up the dosage with just a small amount more each week until you reach your desired level without negative side effects.

All the best,


Jim Dillan

Hi Pratik,

A tablespoon or two of ground flaxseeds would be fine to take but it would be best to have it at different times than flax oil. So if you have one in the morning have the other in the evening.

All the best,



Few years ago I had 3 small clots in the lungs and was 10 days in hospital – they couldn’t find a cause and I was told I can get them any time again in the future. I was put on Warfarin for 6 months but VQ Scans were showing that my clots were not dissolving. By a chance I started to use organic cold press flaxseed oil (Melrose) in last 6 weeks prior to my last VQScan and I couldn’t believe when doctor told me happily that all my clots have dissolved. I was happy to but this time I didn’t know that flaxseed oil has a power to dissolve the clots. When 2 years later I read about this in a Halth and Haling magazine I’m using “religiously” flaxseed oil every day as a prevention for getting clots. I used to have it up to 5 teaspoons every day for about 3 years but last few years I just have it with my salads and vegetables. I never had any side effects, clotting blood is normal but it’s true that bruising is easier. Some brands of flaxseed oil are so bitter and awful smelling but organic cold press Melrose brand is a nicest. It is slightly bitter but very pleasant to use and I have embraced that flavour. Flaxseed oil is my guardian “dog” against the clots and so far about 10 years past and I’m clots free. That’s my experience and very positive.

Cathy Lehman

I take a large tablespoon of FS oil in my oatmeal each day. I am having gastro problems of serious bloating (going up in pants size–waistline only), and abdominal pain. I have undergone 7 expensive medical tests–CATSCANs, etc. We can find nothing causing this. Could it be the oil?
I am desperate to find the cause. Thank you.

Jim Dillan

Hi Cathy,

It would be uncommon but possible as people have many different reactions and the cause of intestinal problems are often several hours before they appear.

If you have dairy milk with your oatmeal though this is a far more likely culprit. This article has more on this and some other common causes https://superfoodprofiles.com/go/3-little-known-factors-damage-digestion

All the best,


Jim Dillan

Hi Doris,

Great to hear that flaxseed oil worked so well for you against blood clots. There are so many benefits throughout the body when you increase your omega 3 content. Most people have far too little and far too much damaging processed omega 6 from vegetable oil.

All the best,


Tammy A Bond

Enjoying all the information, but I like to keep it simple. Will taking a flaxseed oil capsule with with overall weight loss. I have a texture problem with taking oils, can’t swallow. Tried adding flaxseed to meals but kept forgetting..(eating on the run). So can I find a pill, capsule that I can take daily, if so, how much? Also, I love fish. Do I need to worry about eating too much fish, if I take a daily flaxseed pill?

Jim Dillan

Hi Tammy,

Most people get an oversupply of omega-6 from vegetable oils and not enough omega-3 so it’s difficult to get too much, even eating regular fish and taking flaxseed oil. This article has good capsules to take https://superfoodprofiles.com/where-to-buy-flaxseed-oil-online and a higher omega-3 intake is often associated with less unhealthy food cravings, thus improved weight loss.

All the best,


Cris Seño

Good day sir,……can i take only 1000mg of flax oil regularly?

Lester Bijkerk

I am vegetarian and I am fifteen years old. How much flaxseed oil spoonfuls would you recommend me to take per day?


I take a 1000mg flaxseed oil capsule. once a day. I have lost weight easily but I have increased breast tenderness. I have been taking the capsules for a month. Is this a normal reaction to start with, is it bringing out all the toxins? Thank you.

Jim Dillan

Hi Cris,

This would be a good starting amount for most people which could be increased after a week or two if it is well tolerated.

All the best,


Jim Dillan

Hi Lester,

You should be fine using the dosage method used half way down in the article https://superfoodprofiles.com/flaxseed-oil-side-effects-dosage but it’s good to start off slow as suggested.

All the best,


Jim Dillan

Hi Sarah,

Interestingly, while some resources recommend flax specifically for breast tenderness, I can see quite a few comments saying taking it increased breast tenderness.

I would recommend holding off on it for a while and discussing taking it with a healthcare professional. Perhaps try another omega 3 source like fish oil and see if you don’t get the same issue.

All the best,


Vijay Laxmi

Can I just take 1 TSP of flax seeds raw.i mean just chew them and will it be fine for me.me a 35 female.little overweight. thanks

Jim Dillan

Hi Vijay,

I would at least use ground flaxseed as the whole seeds might be rough for your digestive tract. There is a comparison of ground flaxseed vs flaxseed oil here: https://superfoodprofiles.com/flaxseed-vs-flaxseed-oil

All the best,


W Kinley

I started the Budwig protocol a week ago for prostate cancer (in remission?) which is 4tbs of cottage cheese and 2tbs of flax seed oil with 1tbs of ground flax seed. It a little early to tell, but I think I feel better. I haven’t noticed any side effects.

Bill Kinley

I am 78 years old and was diagnosed with aggressive prostate cancer 15 months ago. I went through chemo (Taxotere). I have stage IV cancer but seemingly in remission. I started the Budwig protocol a couple weeks ago and have seen no adverse effects. As you probably know this is 2 tbs of flaxseed oil in 4 tbs of cottage cheese with 1 tbs of ground flaxseeds. I take it every morning at or before breakfast. Should I be concerned about the high dosage of flaxseed and flaxseed oil? If so what should I look for?


Jim Dillan

Hi Bill,

If you’re not experiencing any of the side effects mentioned in the article https://superfoodprofiles.com/flaxseed-oil-side-effects-dosage I don’t think so. Though you should discuss the amount of flaxseed oil you’re taking with your physician as it may affect other medications.

All the best,


Ruth verran

I am very low in omega 3’s. Will consuming flaxseed oil help?


Hi Jim,

Ive just started taking 1000mg (1 capsule) of Flaxseed Oil and 240mg (x2 capsule) Cod Liver Oil daily for almost a week now.. However, I’m starting to wonder if its ok to take both supplements? Would truly appreciate your advice and opinion.


Morning Bill. I take 2 capsules a week. I need to know if there could be any side affects with this.
Also. Is it good to apply the oil on your face and body? Would that count as a dosage?

Jim Dillan

Hi Johanna,

2 capsules a week is a small dosage and shouldn’t cause side effects. The recommended dosage is in the article.

This article covers using flaxseed oil of your face https://superfoodprofiles.com/flaxseed-oil-dry-skin

All the best,


Jim Dillan

Hi Halysha,

It is fine to take both supplements, ideally the cod liver oil in the morning as vitamin D is best then and the flaxseed oil in the evening with dinner.

http://www.cancure.org/10-list-of-clinics-in-the-united-states-offering-alternative-therapies/15-list-of-clinics-in-the-united-states-offering-alternative-therapieszAll the best,


Jim Dillan

Hi Ruth,

Yes, flaxseed oil is a good source of ALA omega 3 fats.

All the best,


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