I see no problem with using fish oil capsules and flax seed together. I've done it many times without any side effects.

As you know, flaxseed oil provides alpha linolenic acid (ALA), an omega 3 fatty acid.

Fish oils provide eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

When taking flaxseed oil, your body takes the ALA and converts it into EPA and DHA through an enzymatic process.

Unfortunately, the conversion process isn't too efficient. Studies found men can only convert ALA to EPA by about 8%. The conversion of ALA to DHA was even lower at 0.1%.

If you're looking for an excellent source of EPA and DHA, you're probably better off with using fish oils. You get a higher amount of EPA and DHA per dose, compared to using flaxseed oil.

You may also save yourself some money as you won't need to take flaxseed oil if you're already getting fish oils in your diet.

There are some big differences between using fish oils and flaxseed oil.

Visit my webpage on Fish Oil versus Flaxseed Oil for more details.

I see nothing wrong with combining flax oil and fish oil. But with both being Omega 3 sources, taking either one of them - and not both - will provide ample nourishment for this particular Essential Fatty Acid.

While fish oils contain a higher concentration of Omega 3's, you can always increase your intake of flax seed to meet the recommended daily volume.

Personally, I prefer to take milled flax seed which could be easily sprinkled over the meals of the day and also with beverages.

Moreover, the sprinkled kernels blends well with many foods than that of fish oil. Here is an article that comparatively tackles fish oil and flax seed oil.