In most cases, it is natural and healthy for a person to experience intestinal gas. It is not uncommon for farts to be either smelly or produce no odor at all. Health experts typically consider both to be normal.

A fart, often known as gas or flatulence, is the buildup of gases within the intestines. These gases are a combination of air that a person swallows and the gas that is produced as a result of digesting food. Flatulence is the passage of intestinal gas, known as flatus, through the rectum.

It is a normal part of how the body works and often not a health concern. In some cases, a person can pass gas silently and without much notice. In other cases, the passing of gas can be loud and produce a strong smell.

Although it is common for flatulence to have an odor, certain foods, medications, or underlying health problems can affect the amount and smell of gas in the digestive tract.

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Causes of strong-smelling flatulence can range from harmless to potentially severe.

Flatulence consists of multiple gases. Typically, the cause of most bad odors from farting is due to intestinal bacteria producing sulfur-containg compounds, such as hydrogen sulfide.

Due to the number of potential causes, it may not always be easy to identify what is causing a person to produce strong-smelling flatulence. Many reasons revolve around food or medication. However, some causes may indicate an underlying health condition.

The following are some common causes of odorous gas:

Intolerance to food

Food intolerance can be a common cause of flatulence.

Examples of food intolerances that can cause a person to pass gas include lactose and gluten intolerance. In both of these conditions, the body’s inability to break down lactose or gluten causes gas to build up and eventually be released.

High FODMAP foods can also cause gas and bloating as they can be challenging to digest.

Other people may have food intolerance due to a disease such as celiac disease. This is an autoimmune disease that causes injuries to the digestive tract. People with celiac disease have difficulty digesting gluten, which is found in wheat products. A person with celiac disease may also experience:

If a person suspects food allergies or intolerances, they should speak with a doctor to test for these conditions. This will help find the exact cause and allow the person to avoid foods that might cause gastrointestinal distress.

Food high in fiber

High fiber foods can be challenging to digest. Although they are beneficial for people’s overall health and well-being, these slow-digesting foods break down or ferment in the digestive tract.

The fermentation process produces an odorous gas.

High fiber foods such as cruciferous vegetables, can contain more sulfur than other types. This can cause the makeup of a person’s fart to change to include more sulfur, which has a distinct odor and will cause the person to produce smellier gas. Examples of cruciferous vegetables include:

  • broccoli
  • radish
  • kale
  • cauliflower
  • cabbage
  • kohlrabi
  • Chinese cabbage
  • wasabi

Medications

Certain medications can cause someone to produce flatulence. Examples of medications that can result in excessive or odorous flatulence include:

Constipation

Constipation occurs when stool builds up in the colon or large intestine and cannot exit.

The buildup of stool in the colon can cause a buildup of gas. This extra gas may cause bloating and discomfort. When finally released, the gas can be odorous.

SIBO

SIBO refers toTrusted Source an overgrowth of bacteria or a change in the type of bacteria in the small intestine. The bacteria can produce excessive gas alongside other symptoms such as:

  • weight loss
  • diarrhea
  • bloating

It can also result in various vitamin deficiencies, such asTrusted Source vitamin B12, which can come with its own set of symptoms.

Stomach upset

If a person has developed a stomach bug or food poisoning, they may experience excessive and odorous gas. Other symptoms may include:

  • pain in the abdomen
  • diarrhea
  • fever
  • nausea
  • vomiting
  • fatigue

Colon cancer

Though not as common, a person may experience excessive and odorous gas due to the presence of cancer of the colon. Colon cancer can cause unexplained constipation, which can cause gas and bloating.

After 45 years of ageTrusted Source, a person at average risk for colon cancer should test to check for colon cancer.

In many cases, a person can try to treat flatulence at home. Depending on the cause, changes in diet may be enough to reduce excessive or odorous flatulence. These changes may require eating less of or avoiding several foods, which can vary from person to person.

In other cases, an individual may find that medication is the cause. For over-the-counter medications, a person will likely find relief by stopping the medication. For prescription medications, it is advisable to speak to a doctor about alternatives.

A person may wish to contact a doctor if:

  • they experience additional symptoms, such as persistent stomach ache, bloating, constipation, or diarrhea
  • they are losing weight without trying to
  • there is blood present in their stool
  • changes to medication do not bring relief
  • alterations to diet do not bring improvement

In these cases, the gas may be due to an infection or an underlying condition that needs treatment. A doctor can perform tests to determine exactly what is causing the gas and decide on a treatment plan for the individual.

For those whose gas occurs from food intake, prevention typically involves changing their diet. A person can try tracking food intake and times when they experience odorous flatulence. They can then eliminate or reduce the amount of the food or foods that cause the gas.

Some tips to avoid excessive and odorous gas include:

  • eating smaller portions
  • avoiding trigger foods
  • avoiding naturally smelly foods
  • eating slowly
  • drinking more water
  • avoiding carbonated drinks

Strong-smelling flatulence is not always a cause for concern. Most people will find that they can manage it at home with changes to their diet.

Others may need to seek out medical advice and attention if the flatulence does not resolve after avoiding certain foods or medications.

If a person is experiencing persistent strong-smelling flatulence, this could indicate food intolerances, gastrointestinal problems, or a side effect from certain medications.

Foods that may cause odorous farts are those that people may be intolerant to, such as dairy or gluten products, or foods rich in fiber, such as navy beans, broccoli, avocado, and buckwheat.

Flatulence is normal, healthy, and a way for the body to release intestinal gas. As such, it is good for a person to pass gas, particularly if it is causing discomfort. While it is healthy to pass gas, excessive or smelly flatulence could indicate a potential digestive problem.

A person may notice strong-smelling flatulence during their period. This may be due to changes in gut bacteria during menstruation and consuming certain foods, such as dairy and starchy carbs, due to period cravings.