Why smelly farts occur and how to reduce the scent


I have a problem with gas. I’ve been told that flatulence is a common occurrence with IBS. Sometimes, they don’t cause me pain, but most times, the passing wind announces itself with bloating and discomfort. I’ll chew a few antacids or take a histamine blocker (ie, Tagamet®, Pepcid®, Zantac®), which helps control bloating and cramping. But what I can’t control is the smell.

I can never tell if the incoming wind will be silent or if it will announce itself loudly. If I’m in a public space and surrounded by people, I’ll quickly blend in with the crowd and hope no one looks in my direction. However, in a small gathering like an exercise class, it’s not as easy to distance myself. Luckily, there’s an unspoken courtesy not to flinch, grab the nose, or say something rude.


This message from an IBS Life reader led us to revisit the causes of flatulence and what readers can do to reduce these occurrences. People with IBS have trouble with gas because of how the nerves and muscles in their gut work. The root cause often differs from one person to the next, and no single treatment works for everyone.

What causes the odorous scent?


According to a past study published in Gastroenterology & Hepatology, there are several reasons why gas smells. Most of them are due to food-related factors, such as:

  • Consuming high fiber foods. Certain foods, like broccoli, Bok choy, cabbage, and asparagus, take longer to break down in the digestive tract, so they ferment longer. Most can smell like rotten eggs because they contain sulfur, a chemical. Other foods known to lead to gas are beans, cauliflower, and kale.

  • Dietary restrictions. People with lactose intolerance can’t break down sugar easily, which is why those with celiac disease or gluten allergies have digestive issues in the GI tract, leading to pungent odors. Bloating and diarrhea also tend to follow.

  • Stool buildup. People with IBS-C have a slow transit time, which leads to the stool staying in the colon longer — and simmering longer.

  • Alcohol consumption. The yeast and carbohydrates in beer can ferment in the gut, turning the morning after into a gassy episode. Switching to wine won’t alleviate that risk. Almost all wines contain sulfites, a natural by-product and preservative of the fermentation process, which contain sulfur compounds that can smell as bad as beer farts.

Being aware of what you eat – and how much to eat – can help reduce gas production and the scent that comes with it.


There are also medications meant for certain health conditions (other than IBS) that can lead to these “fart sessions,” as one IBS Life reader calls it. Unfortunately, flatulence is a side effect not frequently mentioned by physicians or pharmacists — unless the patient asks.

  • Antibiotics. Most IBS Life readers already know that antibiotics can upset the intestinal flora in the gut. Some are slightly worse than others in triggering gassy episodes. Frequent culprits include ciprofloxacin and amoxicillin (eg, Cipro®, Amoxil®).

  • Medications for depression. Commonly used medications for treating depression or anxiety are venlafaxine, divalproex, pregabalin, and escitalopram (ie, Depakote®, Effexor®, Lexapro®, and Lyrica®). A side effect is gas.

  • Diabetes medication. Metformin® is a drug used to control blood sugar in people with diabetes. Unfortunately, the medication also disrupts the digestive system, which leads to constant flatulence.

Since people with IBS tend to release gas more often than the general public, it’s important to bring up the subject at the next medical visit or when a medication is prescribed. Another way to reduce the risk of passing gas in public locations is to practice yoga, which helps move the trapped air along the GI tract. There are two articles in IBS Life that might be useful: Five Yoga Poses and Restorative Yoga.

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