Period Farts: Why You Are Gassier Before & During Your Period

If you are gassier in the week before your period, and gassier again in the first day or two of bleeding, you are not imagining it and there is nothing wrong with you. They are two different things happening for two different reasons, and both of them are ordinary.

Why period farts happen before your period

Everyone produces gas, and most of us pass it between thirteen and twenty one times a day, which is far more than anyone would guess. Most of it is fermentation. The bacteria living in your large intestine work on whatever your small intestine did not absorb, and gas is what they give off while they do it. That is the whole of it. It is a sign the system is running, not a sign it is broken.

What changes across the month is how long that fermentation gets to go on for. Progesterone rises after you ovulate, and it relaxes smooth muscle everywhere it finds it, including the muscle that moves things through your gut. Everything slows. Not every study agrees on how much, but several have measured transit through the gut running slower in the second half of the cycle than in the first. Slower going means more time for the bacteria to work, and more gas by the time you reach the week before you bleed.

The same slowdown is why so many of us are constipated and heavy in that week. If you want the fuller picture of what your body is doing then, I have written about the luteal phase in its own post.

Why it changes again during your period

Then your period arrives and the whole thing flips, sometimes overnight.

As the lining of your uterus breaks down it releases prostaglandins, which are what make the uterus cramp. They do not stay politely in one place. They have a powerful stimulating effect on the gut as well, which is why the first day or two so often brings looser stools, more urgency and gas that turns up alongside the cramping. Progesterone has dropped away by then too, so the constipated, sluggish week gives way to the opposite almost immediately.

None of that is your body going wrong. It is your body doing a big piece of work. It has spent a fortnight building a lining and it is now letting it go, and the cramping, the looseness and the gas are all part of the muscle work of that. It is the same cycle, at two different points, and it is the swing between the two that makes women think their digestion is broken.

What is worth paying attention to is the degree of it. Prostaglandins are what make the uterus contract, and some women respond to them far more strongly, which is where a period stops being uncomfortable and starts being painful. Histamine is part of the picture for some women too. Neither is something to work out from a blog post, and both are worth taking to a doctor or the practitioner you work with, particularly if the pain stops your day. There is more on what is worth having looked at further down.

Why period farts smell worse

This is the part women ask about and almost nobody answers, so here it is plainly.

The smell is sulfur. Fermentation produces gases like methane and hydrogen sulfide, and the longer things sit in there, the more of that work gets done. Slow transit in the second half of your cycle gives them the time. What comes out at the end of it is more concentrated than the same meal would have been a fortnight earlier.

Appetite plays into it too. If the week before your period has you reaching for sweeter and richer food than usual, and for most of us it does, you are also handing those bacteria more to work with.

We do not fart like the boys

Most digestion research was done on men, who do not have a monthly hormonal shift running underneath everything, so the advice built on that research does not account for one. It is the reason so much standard digestion advice does not quite land for us.

If your digestion seems to have a personality that changes fortnightly, that is why. Track it for a couple of months alongside your cycle and you will usually find your own pattern sitting there in the notes, in the same week every time.

What actually helps

None of these are treatments and none of them cost anything. Take whichever ones appeal and leave the rest.

• •Try chewing properly, and slower than feels natural. Most of digestion is decided in your mouth, before anything reaches your gut.
• •See how it feels to sit down to eat, with your phone somewhere else. Your body does not digest well while braced, and standing at the bench between two things is not really a meal.
• •Take a few slow breaths into your belly before you start eating, the sort where your ribs widen rather than your shoulders lifting. It brings you out of the braced state, and a diaphragm moving properly gives everything underneath it a gentle nudge as it goes.
• •Try easing off what you drink alongside your food. A sip is fine, a whole glass dilutes what you are trying to break down.
• •A slow tummy massage is worth a try, clockwise, following the direction things travel.
• •Give yourself a full five minutes on the toilet rather than rushing off. Unhurried is the whole trick.
• •Ginger and mint tea, which is old advice because it is decent advice.
• •Try a food diary for a fortnight. Not to find a villain, because it is rarely one villain food, but to notice patterns you cannot hold in your head.

If eating has become a thing you argue with yourself about, learning to eat intuitively is the better place to start. Food combining is another lens on the same question, and it is the one that helped me most.

When it is not just gas

Please have it looked at properly if the change is significant or if it persists.

Blood, pain that stops you doing things, unexplained weight change, a fever, or a change in your bowels that lasts more than a couple of weeks are all doctor's business rather than blog business.

If you suspect a food allergy or an intolerance, that needs proper testing rather than guessing, and it starts with your doctor. I spent a long time trying to work things out alone that somebody qualified could have identified quickly, and I would rather you skipped that part.

One specific note, because it comes up every time: activated charcoal is often suggested for gas, and it binds drugs in the digestive tract and reduces how much of them your body absorbs. If you take anything prescribed, talk to your pharmacist before going near it.

Girls learn to hold it in

It starts young. At school a boy could let one rip and it was funny, and when a girl did it the whole room made a thing of it. So girls learn to hold. Somewhere in there we pick up the idea that a woman is supposed to smell like flowers, and that a body doing an ordinary body thing is a failure of manners.

So we get good at excuses. I have blamed the dog. I have blamed whoever was standing nearest. Mostly I would sit very still, go red in the face and carry on as though it were not me.

Holding it in does not make it go away. It waits, and it usually comes back with cramping and a tight, stretched feeling on top of it, which is a lot to carry around for the sake of a manner nobody taught the boys.

You are not disgusting. You are a mammal with a digestive tract, and it is doing exactly what digestive tracts do, on the schedule your hormones set for it.

The shame is the bit worth getting rid of. The gas is mostly just information.

If you want to go further

If you are curious about what is actually living in your gut, a microbiome test will show you. It is collected at home, and the laboratory reads which bacteria are present and in what proportions.

If you are in Australia, the gut microbiome test through i-screen is the one I use. Please note I am an affiliate for them, so I earn a commission if you buy through that link. If you are anywhere else, look for the equivalent where you are.

It is a picture of your gut, not a diagnosis, and it does not test for allergy or intolerance. Take the results to your doctor or the practitioner you work with, because what to do with them is the part that matters.

Where to go next

If the pattern in this post sounds like yours, living cyclically is the wider version of it: shaping the month around what your body is actually doing rather than pushing through all four weeks the same way.

Eating for your cycle is the food side of that, phase by phase.

And if your digestion tends to go first whenever life gets heavy, the link between your emotions and your gut is worth reading, because that one is not a food problem at all.

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