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Everyone has a certain amount of gas in the gut. Some people, however, are sensitive to normal amounts. They experience pain, burp excessively or pass large amounts of wind as the gas passes through the gut. Occasionally, greater than normal amounts of gas are produced. There are several situations in which this may occur, including air swallowing, dietary factors and, less commonly, bowel diseases. Changes to the diet, various medicines and products which deodorise gas may be helpful.

See also separate leaflet called Abdominal Pain.

The Gut - simple

There is always a certain amount of gas in the bowel. Most of this comes from air swallowed whilst you are eating or drinking. It can also happen during smoking or when swallowing saliva. Larger amounts can be swallowed when you eat quickly, gulp down a drink or chew gum. The swallowed air goes down into the gullet (oesophagus).

If you are sitting up, the air tends to go back up the oesophagus and escapes again through the mouth in the process of belching. If you are lying flat, the air tends to pass down into the stomach, enter the small  bowel (small intestine) and eventually escapes through the back passage (anus). People often refer to this as 'farting' or, more politely, 'passing wind'.

Gas can also be produced due to germs (bacteria) acting on partially digested food in the gut. This is more likely to happen with some foods than others. Broccoli, baked beans and brussels sprouts are well-known culprits. The gas produced may contain traces of a chemical called sulphur. This is responsible for the unpleasant smell experienced when you pass wind through the back passage.

Bloating is the term used when the tummy feels blown out, tight or full of gas. It may look larger than normal and the waistband of a skirt or pair of trousers may feel uncomfortable. You may experience crampy tummy pains.

Gas-related symptoms include burping excessively, passing a lot of wind from the back passage, crampy stomach pains and bloating. Gas sometimes settles in the curves of the large bowel (large intestine) under the liver or spleen. This can cause pain in the upper right or upper left areas of your tummy.

Most people who are bothered by this type of symptoms do not actually produce more gas than usual, they are just more sensitive to normal amounts.This typically happens inirritable bowel syndrome, a condition in which bouts of tummy pain are associated with bloating and changes in bowel habit such as constipation and diarrhoea. See separate leaflet called Irritable Bowel Syndrome.

Everybody has gas-related symptoms from time to time. In most cases, this is part of the natural working of the body and the symptoms soon pass. As mentioned above, some people are sensitive to normal amounts of gas in the tummy. The reasons for this are not entirely clear.

There are some conditions associated with larger than normal amounts of gas in the tummy:

Swallowing too much air

This is called aerophagia. You may not be aware of it but you may be swallowing air frequently or in large amounts. This often happens in people who are under stress. It can be aggravated by chewing gum and smoking.


Foods which are well known to increase the amount of gas in the gut include:

  • Broccoli.
  • Brussels sprouts.
  • Starchy foods such as potatoes, corn and noodles.
  • Foods high in soluble fibre (eg, fruit, peas and beans).

Lactose intolerance

Lactose intolerance happens when your body has difficulty digesting lactose. Lactose is present in milk and foods which are made with milk. Lactose intolerance causes diarrhoea, tummy pains and bloating. See separate leaflet called Lactose Intolerance.

Intolerance to food sugars

Intolerance to sugars in certain foods can occur. Fructose intolerance is the most common. Foods high in fructose include dried fruit, honey, sucrose, onions and artichokes. Sorbitol is another sugar to which you can be intolerant. It is found in chewing gum and 'sugar-free' sweets.


Check the leaflet of any medicines you are taking, as wind, gas or bloating can be side-effects. Metformin (a medicine for diabetes) and lactulose (a laxative) are well known to cause these symptoms.

Diseases causing increased gas

Most people with gas-related symptoms have increased sensitivity to gas or have one of the causes of increased gas production mentioned above. However, occasionally these symptoms can be caused by long-term diseases of the bowel. All of them can cause at least one gas-related symptom (ie tummy pain, excess wind or bloating).

Examples include:

Coeliac disease
Coeliac diseaseis caused by intolerance to a protein called gluten which is found in wheat. See separate leaflet called Coeliac Disease.

Diverticulitisoccurs when small pouches in the wall of the large bowel ('diverticula') become infected. See separate leaflet called Diverticula (including Diverticulosis, Diverticular Disease and Diverticulitis).

Short bowel syndrome
Short bowel syndrome can be a complication of bowel surgery. If more than half the small bowel is removed during surgery this can cause difficulties in food absorption.

Scleroderma is a condition which causes thickening of the skin and sometimes the internal organs. When the gut is affected it can cause problems in stomach emptying and irregularity of bowel movement. This can lead to bloating, constipation and diarrhoea. See separate leaflet called Scleroderma - Systemic Sclerosis.

Ovarian cancer
Ovarian cancer is mentioned here because, although cancer of the ovary is not a disease of the bowel, it can cause symptoms which can be confused with bowel disease. These can include feeling full quickly or loss of appetite, tummy pains and bloating. See separate leaflet called Ovarian Cancer.

Most people with these symptoms do not need any tests. However, you may need tests if you have more worrying symptoms. These can include:

The tests may include:

Changes to your diet

  • Keep a record of what you eat and drink to see if there are any foods or beverages which could be associated with your symptoms. These can include milk and milk products, certain fruits and vegetables, whole grains, artificial sweeteners and fizzy drinks.
  • If you are lactose-intolerant you will need to avoid lactose-containing foods. Your doctor will advise how best to do this without developing complications such as calcium and mineral deficiency.
  • If you are fructose-intolerant you should avoid fructose-containing foods. Fructose is used as a sweetener in many processed foods; look for 'high in fructose corn syrup' on the label.
  • Live micro-organisms (probiotics) may be helpful, although the evidence is not conclusive.


Exercise has been shown to improve gas-related symptoms. This is partly due to the upright position, as lying flat tends to stop gas from moving round the body.

Over-the-counter medicines

Simeticone is worth a try as it is said to break up gas bubbles. There is, however, no convincing evidence in the scientific literature to support its use. It is usually sold in combination with an antacid.

Charcoal preparations, which are meant to absorb gas, may also be tried. There is some scientific evidence that it is useful.

Medicines which encourage the movement of the gut (prokinetic medicines) can be quite helpful if you have excessive belching and bloating. Most of these are prescription-only preparations but peppermint can be bought in various forms.

Medicines which relieve spasm may also be helpful for bloating and distension. Medicines in this group, available without prescription, include mebeverine and alverine.

Bismuth subsalicylate has been shown to reduce the smell of gas passed through the back passage (anus). However, it should not be taken regularly due to side-effects. It is best reserved for occasional use - eg, social occasions.

Deodorising products

Carbon fibre underwear appears to be effective but is expensive. Charcoal pads and cushions are cheaper but may not be as effective.

Original Author:
Dr Laurence Knott
Current Version:
Peer Reviewer:
Dr Hayley Willacy
Document ID:
29098 (v1)
Last Checked:
Next Review:
The Information Standard - certified member
Now read about Flatulence and Wind

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