Everyone passes gas, or farts—a lot. On average, people fart about 14 times a day. These are odorless and often silent most of the time, so you may not even be thinking about farting (also known as flatulence) at all. However, some people may notice that their farts are beginning to have a foul odor. While it’s often an issue of something that you ate, other reasons can cause “stinky farts,” and some are serious enough so that you should see your physician. Read on to learn more about why farts smell and when you should see a doctor. 

What Causes Farting?

It is called passing gas for a reason—flatulence is gas collected in your digestive tract that is released through the anus. For the most part, you’re collecting this gas every second of the day. Even swallowing air can cause farting, but it usually has to do with food digestion. Farting is a mixture of carbon dioxide, hydrogen, and methane. Farting is completely normal and is part of the digestive process. Most of the time, farts aren’t noticeable, and you’re likely not thinking about it at all unless you’re trying to ensure others don’t hear your flatulence. While some farts are normal, others can be indicative of a problem. If your farts are consistently causing symptoms such as abdominal pain and they have a foul odor, it may be time to check in with your healthcare provider. Some of the more benign causes of farting include:

  • Swallowing air. This is one of the most basic and straightforward causes of farting. While you may equate swallowing air with hiccups, it can also cause farting. How do you “swallow air?” It can happen from eating or drinking too fast, smoking, drinking carbonated beverages, and chewing gum. If you swallow a lot of air, you may notice an increase in your burping as well. 
  • Food choices. Occasionally, a bad case of gas and bloating is caused by the food you eat. Foods high in fiber will naturally cause gas to occur, and if you eat a high-fiber diet, this may be the root cause of flatulence. Foods that are high in fiber include:
  • Cabbage
  • Asparagus
  • Broccoli
  • Bok choy
  • Apples 
  • Lentils
  • Medication. While this isn’t a very common reason for farting, some medications can cause excessive flatulence. If you’re on a round of antibiotics, for instance, you may notice an increase in gas. This is because while antibiotics are eliminating harmful pathogens, they’re also killing off the “good” bacteria in your gut. This may cause excessive farting or smelly farts. You can also experience constipation with antibiotics. 

Why Do My Farts Smell Bad?

There are other reasons for farting that aren’t quite as basic as swallowing air, food choices, and medication. Sometimes, smelly farts are alerting you that you’re having a problem. While these reasons are less common, if you’re consistently experiencing GI upset, such as smelly farts, constipation, and diarrhea, it may be time to talk to your doctor. Other reasons for smelly farts include:

  • Intolerance to food. While occasionally food choices can cause stinky farts, a consistent foul odor may be due to sensitivity to certain foods or complete intolerance. One of the more common ingredients that patients react to is gluten. If you’re intolerant of gluten, it can manifest in one of two ways: gluten sensitivity or celiac disease. A good rule of thumb is to eliminate foods with gluten for a week or so to see if the smelly farts disappear. A sensitivity to gluten means you should avoid foods with gluten, while celiac disease indicates you must avoid foods with gluten, as it can harm your digestive tract over time. Some other symptoms of celiac disease include:
  • Unexplained weight loss
  • Fatigue
  • Bloating 
  • Diarrhea
  • Skin problems (such as a rash)
  • Constipation. While this likely isn’t an issue that you need to be evaluated for, it can be painful and can affect your quality of life until it’s resolved. Smelly farts can indicate that you have a backup of stool in your colon, which causes gas and bacteria. Typically, a stool softener paired with an over-the-counter laxative can help solve the problem, but if it persists, see your doctor as constipation can be a symptom of other GI distress. 
  • Infection. It is possible to have a bacterial infection in the digestive tract that is causing smelly farts. If you have a bacterial infection in the digestive tract, it is often paired with abdominal pain and diarrhea. 
  • Colon cancer. In extremely rare cases, excessive gas and smelly farts can be a marker for colon cancer. Colon cancer forms as polyps in the colon and sometimes the rectum. This naturally obstructs the bowel, leading to symptoms such as bloating and smelly farts, among others. If you’ve visited your physician because of smelly farts, and you’ve eliminated all other reasons and causes, they may suggest a colonoscopy. This is the gold standard when it comes to testing for colon cancer. If you are age 45 or over, you should schedule a colonoscopy with your doctor, as this is the age you should begin testing for colon cancer, regardless of symptoms. 

When to See a Doctor for Flatulence

For the most part, you shouldn’t worry if you occasionally have excessive gas or smelly farts. However, in some cases, you should see your doctor. If your gas is paired with other symptoms, it’s a good idea to be evaluated. Some more serious symptoms include blood in the stool, unexplained weight loss, fever, and muscle weakness. But if you’re experiencing consistent bloating, diarrhea or constipation, nausea, or stomach cramps, you should see your doctor as well. 

How Can I Prevent Gas?

If you occasionally have a foul odor or excessive gas, lifestyle choices can prevent this. Some tips for gas prevention include:

  • Slow down your eating. Take your time when you eat meals and eat smaller portions more often each day. 
  • Avoid soda and carbonated beverages. These can cause you to swallow air, which can cause gas. 
  • Drink water. We’ve all heard that 8 glasses of water each day is best. But the truth is, how much water you need varies. But there are some basic guidelines:
    • For men, the Institute of Medicine (IOM) recommends a total of 13 cups (about 3 liters) of fluid each day.
    • For women, they suggest 9 cups (a little over 2 liters) of fluid each day. Pregnant women should drink about 10 cups of water daily. Those who breastfeed need about 12 cups.
    • If you’re outside on a hot day, or doing something that makes you sweat a lot, you’ll need to drink more fluids to stay hydrated. The same is true if you have an illness that causes you to throw up, have diarrhea, or run a fever.
    • If you have a condition like heart failure or a particular type of kidney disease, you may need to limit your fluid intake. Talk to your doctor about what’s right for you.
  • Take probiotics or eat probiotic-rich foods. Foods such as yogurt can improve digestion.
  • Avoid eating too much fiber. While it’s a good idea to have fiber in your diet, eating an abundance of fiber-rich foods can cause GI upset.       

If you need more information on why your farts smell, or you think you may have excessive flatulence, contact Digestive Health Partners. We offer comprehensive care for all types of gastrointestinal problems.