Flatulence is passing gas from the digestive system out of the back passage. It is more commonly known as "passing wind", or "farting".
Farting is often something laughed about, but excessive flatulence can be embarrassing and make you feel uncomfortable around others. However, it can usually be controlled with changes to your diet and lifestyle.
Flatulence is a normal biological process and is something everyone experiences regularly. Some people pass wind only a few times a day, others a lot more, but the average is said to be about 15 times a day.
Why it happens
When you swallow food, water or saliva, you also swallow small amounts of air, which collects in the digestive system. Gases can also build up when you digest food.
The body needs to get rid of the build-up by farting (flatulence) or burping (belching).
Sometimes, you may not notice you have passed wind because most of the gases are odourless and are often released in small quantities.
Flatulence usually only has a bad smell if it contains gases that smell, such as sulphur. However, it is important to remember that it is normal for the gas you pass to sometimes smell a bit.
Excessive flatulence can be caused by swallowing more air than usual or eating food that is difficult to digest. It can also be related to an underlying health problem that affects the digestive system, such as irritable bowel syndrome (IBS).
When to see your GP
There are no medical guidelines defining what the normal frequency or volume of flatulence is. You are therefore probably the best person to assess your own symptoms.
You should see your GP if your flatulence is particularly troublesome, such as frequently passing smelly gas, for example.
You should also visit your GP if you experience additional symptoms, such as:
persistent abdominal pain and bloating
recurring episodes of diarrhoea or constipation
unexplained weight loss
blood in your stools (faeces)
signs of an infection, such as a high temperature, vomiting, chills, joint pain and muscle pain
These symptoms could be an indicator of a more serious health problem and require investigation, such as a blood or stool test to look for an infection.
Controlling the problem
Excessive flatulence can usually be controlled by making changes to your diet and lifestyle, such as:
avoiding foods known to cause flatulence
eating smaller and more frequent meals
eating and drinking slowly
There are also some over-the-counter medications that can help if your flatulence is troublesome, such as charcoal tablets or simethicone.
If your flatulence is related to an underlying health problem, treating the condition may help resolve the problem.
Causes of flatulence
There are several natural causes of flatulence. Flatulence can also be caused by some health conditions that are related to the digestive system.
It is perfectly normal to swallow air while breathing and eating. However, it is easy to swallow a lot more air than usual without realising it. This can cause excessive flatulence.
Excess air can be swallowed by:
sucking on pen tops or hard sweets
having loose fitting dentures
not chewing food slowly and thoroughly (swallowing large pieces of food will result in you swallowing more air)
Hot and fizzy drinks also increase the amount of carbon dioxide in your stomach, although this is more likely to cause belching rather than flatulence.
Food and drink
Much of the food we eat is carbohydrate. Carbohydrates are made up of long chains of sugar molecules. Some carbohydrates cannot be digested and absorbed by the intestines and pass down into your colon. These are known as unabsorbable carbohydrates, or fermentable oligo-, di- and monosaccharides and polyols (FODMAPs).
Your colon contains more than 500 different types of bacteria. The bacteria start to break down the carbohydrates and in the process produce gas, which is released as flatulence.
Foods that contain a high amount of unabsorbable carbohydrates include:
Other foods and drinks containing a sweetener called sorbitol (such as sugar-free gum or slimming products), or a type of sugar called fructose (such as fruit juice), can also cause flatulence.
Certain foods, such as cabbage or onions, can lead to the production of gases containing sulphur, which can result in foul smelling wind.
However, the production of smelly wind can vary from person to person depending on what you eat, so it is up to you to work out which foods cause the most smell.
Health conditions that can cause symptoms of flatulence include:
irritable bowel syndrome (IBS) – a common digestive condition, which can cause stomach cramps, bloating, diarrhoea and constipation
coeliac disease – an intolerance to a protein called gluten, found in wheat, rye and barley
lactose intolerance – where the body is unable to break down lactose (a natural sugar found in milk and dairy products) and cannot absorb it into the blood
gastroenteritis – a stomach and bowel infection
malabsorption – where the intestines are unable to absorb nutrients properly
Excessive flatulence can usually be treated by making changes to your diet and lifestyle.
There are also several over-the-counter treatments available if your flatulence is becoming a problem.
You should try to avoid eating foods high in unabsorbable carbohydrates. See causes of flatulence for a list of these.
However, it's still important to eat a healthy balanced diet, including at least five portions of fruit and vegetables a day. Choose foods that contain carbohydrates that are easy to digest. These include:
citrus fruits, such as oranges
It is important to note that people will react differently to certain foods, so some foods listed above may still cause flatulence. You may find it useful to keep a food diary to see whether certain foods make your symptoms better or worse.
You may also find it useful to eat six small meals a day, rather than three large ones. Smaller meals are easier to digest and may produce less gas.
There is also some evidence to suggest that drinking peppermint tea can help improve the symptoms of flatulence.
When eating, make sure you chew food slowly to reduce the amount of air you swallow. This will also help with digestion.
Avoid chewing gum as it can also cause you to swallow more air than usual. Sugar-free chewing gums also contain chemicals that can cause flatulence
You should also give up smoking if you smoke. Smoking can cause you to swallow more air than usual and tobacco smoke can irritate your digestive system.
See stop smoking for information and advice.
Getting plenty of exercise can help improve the functioning of your digestive system and bowel. It has also been shown to help with bloating and the passage of gas.
Medications and other remedies
There are several over-the-counter remedies that can help treat the symptoms of flatulence, some of which are described below.
Charcoal tablets are a type of medication available over the counter from pharmacists. The charcoal absorbs gas in the digestive system, which helps reduce symptoms.
Charcoal tablets may not be suitable for you if you are currently taking other medication. This is because the charcoal might absorb the medication and make it less effective. If you are taking other medication, ask your GP or pharmacist for advice before taking charcoal tablets.
Clothing containing activated charcoal, or charcoal pads placed inside clothing, can help absorb foul-smelling gas released during flatulence. These products can be purchased online.
Simethicone is another over-the-counter medication that can also sometimes help with gas problems.
Alpha-galactosidase is a dietary supplement that may help improve the digestion of carbohydrates and reduce symptoms of flatulence. It is found in a product called Beano, which has been shown to have some effect in reducing flatulence and is available from some pharmacists and health food shops.
Probiotics may also be useful in treating flatulence. Probiotics are a dietary supplement, usually sold in liquid or capsule form, which encourages the growth of "friendly bacteria" in your digestive system. The "friendly bacteria" should help digestion and reduce the symptoms of flatulence, particularly in people with irritable bowel syndrome (IBS).