Can fish oil cause heavy periods?

Has anyone ever told you to avoid fish oil during your period because it allegedly causes heavy bleeding? If not, congratulations! You’re missing out on one of the greatest hormonal myths out there.

But for those who have heard this claim before and are now feeling anxious about that bottle of cod liver oil they just bought, allow me to put your mind at ease. In short – no, fish oil does not cause heavy periods.

However, if you want a longer (and hopefully funnier) explanation as to why this idea is nothing more than an old wives’ tale, read on!

The Myth

Before we get into why fish oil has no effect whatsoever on menstruation (besides potentially improving menstrual cramps), let’s first unpack where this myth came from in the first place.

One potential culprit for spreading this misinformation could be the overabundance of omega-3 fatty acids found in certain types of fish. Omega-3s are touted as “healthy fats” due to their anti-inflammatory properties and numerous health benefits such as reducing triglyceride levels and promoting heart health. However, some people believe that these same anti-inflammatory effects can lead to a disruption in blood clotting factors which could theoretically result in heavier periods.

Another reason behind the myth may be less scientific and more cultural; women’s bodies are often treated with suspicion or outright fear by society at large so it isn’t surprising that misconceptions about menstruation would arise over time.

Regardless of its origins though, we can safely say that there is absolutely zero evidence supporting the claim that consuming fish oil results in heavier periods.

The Science

There has been extensive research done surrounding the positive benefits of omega-3 fatty acids but very little showing any negative side effects regarding menstrual cycles.

First off – yes – omega 3’s do help regulate hormone production which directly affects our menstrual cycle so technically they do have something to do with periods. Additionally, because they reduce inflammation in the body, omega-3s may help to alleviate menstrual cramps which can be a huge win for anyone who suffers from severe period pain.

But what about those pesky “blood-thinning” effects that some people blame for heavier periods? This is where things get interesting. While omega-3’s may affect blood clotting factors on some level – so does aspirin – and you don’t see people saying not to take aspirin while you’re bleeding out once a month so… yeah.

It’s important here to note that heavy periods can be caused by numerous factors including hormonal imbalances or fibroids but omega 3’s really aren’t one of them.

The Bottom Line

While there are many benefits of taking fish oil (or any other supplement containing Omega-3 fatty acids), suffering from heavier or longer-lasting periods is simply just isn’t one of them.

So feel free to chug down your cod liver oil with wild abandon! Or maybe just try taking it as directed on the bottle since too much fish oil could result in indigestion, diarrhea or bloating…but hey maybe all those lousy side effects will distract you enough from noticing whether or not your period is any “heavier.”

Either way, rest assured that even if Aunt Mildred swears she had a friend whose sister-in-law took fish oil and then practically bled out, there’s no scientific evidence supporting this claim – only centuries worth of myths based on patriarchal fear and misinformation!

Other Ways Fish Oil Affects Us

Okay great! Now we all know our entire reproductive system won’t implode due to consumption of Omega-3s. However did you know there are plenty more ways these tiny little oils benefit us?

Brain Health

How often have we heard how imperative salmon dishes are for brain development? While it may feel like a wives’ tale, there really is some science behind it. Omega-3s help sustain optimal brain function especially when it comes to memory retention and protection against mood disorders such as depression.

Vision

Our eyes have an entirely separate system in place than the rest of our body requiring special fatty acids called DHA’s (one of which is found via omega 3’s). Diets rich in fatty omegas promote both healthy vision development and retention as well as decrease the risk for age-related macular degeneration.

Skin

If you caught those anti-inflammatory properties above then this one should make sense – consuming omega-3 also helps keep our skin clear! Its ability to control inflammation means calming redness or acne flare ups allowing us all to have that desired “healthy” glow no matter how many glasses of wine were involved the night before!

Should Everyone Take Fish Oil Supplements?

While there are always exceptions depending on medical conditions/sensitivity levels – generally speaking, most could potentially benefit from adding a bit more Omega 3 into their lives.

There isn’t technically a daily intake recommendation since everyone’s needs differ but somewhere between 250mg-500mg per day will do its job supporting everything listed above.

Bear in mind that while consuming natural sources such as salmon are fantastic ways to get your omegas and proteins simultaneously, guidelines suggest sustained benefits come from taking supplements instead.

Of course if you just absolutely can’t stand the taste/smell/bitter aftertaste we’ve all experienced with trying not so fresh fish oil out of sheer desperation – there are alternatives.1, 2 Fish-free options range anywhere from flaxseed oils (which exceed even cod liver oils) to algal-based forms so no need for anyone with dietary sensitivities even be left out!

So now you know ; unless you start eating an entire Navy Seal’s worth every day OR your ob-gyn advises against it for underlying reasons, there’s no reason why us menstruating mortals can’t enjoy all the benefits of omega-3s just like everyone else on this silly spinning blue balled planet we call Earth.


  1. Omega 3 Deficiency Symptoms and Foods High in Omega 3 Fish Oils. (2017). Health Ambition. https://www.healthambition.com/omega-3-deficiency-symptoms-foods-high-oil/ 

  2. Brown, M.J.(2021)10 Best Vegetarian and Vegan Sources of Omega- 3 Fatty Acids | Fullscript® . FullScripthttps://fullscript.com/blog/how-to-get-enough-omegas-on-a-plant-based-diet 

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