Functional Bloating – Causes, Symptoms, Treatment

Bloating is common term used to describe the sensation of fullness in the abdomen may or may not correlate with any increase in abdominal size (diameter). It can also be used to describe abdominal distension (visible/measurable enlargement of the abdomen) without any sensation of fullness. Bloating is not an uncommon occurrence – most of us experience a sensation of fullness after a heavy meal or with consuming excessive quantities of carbonated beverages. It usually eases on its own after a short while and belching may help to relieve it. However, the sensation of bloating is also a common symptom of many gastrointestinal disorders like gastritis, peptic ulcer disease and hiatal hernia. Abdominal distension on the hand is not as common – it most likely occurs in a person with some abdominal disorder or even systemic disease.

What is functional bloating?

Functional bloating is the sensation of fullness and/or abdominal distension that is not associated with any disease, either within the abdomen or systemically. Apart from other diseases, it should also not be part of other functional bowel disorders like irritable bowel syndrome (IBS), functional diarrhea or functional constipation in order to be diagnosed as functional bloating. It is important to note that functional abdominalbloating is a prominent feature of irritable bowel syndrome. However, without the abdominal pain associated with change in bowel habit as is seen in IBS, functional bloating is diagnosed on its own.

Functional abdominal bloating is more common in women than men. The pathophysiology behind it is not well understood. There is no significant evidence to suggest that there is fluid accumulation within the abdominal cavity. Some evidence suggests that there may be increased gas accumulation within the gut and abnormal passage of this intestinal gas. The bloating can occur very quickly after eating which means that gas production, if it is indeed due to gas, has to be rapid. Although this mechanism is not clearly understood. This may be associated with food intolerances and abnormal gut bacteria. Weak abdominal muscles may cause the distension to be more pronounced but is not a contributing factor.

Causes of Functional Bloating

The exact cause of functional abdominal bloating is unknown. It is not only associated with gastrointestinal disturbances since it is commonly occurs in women before and during menstruation. Although this progresses and persists over several days, in some cases of functional bloating the distension can vary within hours. Although the cause is not known and is not associated with any pathology (disease) or other functional bowel disorder, it should be noted that bloating on its own can occur for various reasons that can affect any person. This includes :

  • Overeating
  • Carbonated beverages
  • Aerophagia (air swallowing) which in turn may be associated with :
    • Mouth breathing
    • Excessive gum chewing
    • Cigarette smoking
  • Pregnancy

However, bloating due to the causes above is NOT functional bloating. Instead many can be termed physiological bloating in that it is not associated with any disease and will cease once the causative or contributing factors are removed. Functional bloating arises even without predisposing factors and is unlikely to resolve completely even with medication and lifestyle modification.

Idiopathic vs Functional

There is sometimes confusion about functional disorders and how it varies from idiopathic conditions. Idiopathic means that the disease is due to unknown causes. What is important to note here is that there is a disease present. With time this can lead to complications some of which may be fatal. Functional on the other hand is not associated with any disease despite the presence of symptoms. Functional disorders are also not associated with any clearly identifiable causes that will explain the symptoms despite the lack of a disease.

Signs and Symptoms

The sensation of fullness is a symptom while abdominal distension is a clinical sign. A person may complain of fullness after just a few bites of eating or after a meal. This may occur even independently of eating like when associated with the menstrual cycle. Other signs and symptoms are usually not present. In fact the presence of any other signs and symptoms may affect the diagnosis of functional bloating.

Other functional bowel disorders have bloating as a prominent feature and therefore bloating with :

  • nausea, vomiting, upper abdominal pain and excessive belching = functional dyspepsia
  • abdominal pain/discomfort with changes in defecation (constipation/diarrhea) = irritable bowel syndrome

Treatment of Functional Bloating

Firstly functional abdominal bloating has to be diagnosed based on the following criteria :

  • Recurrent bloating (sensation / distension) for at least 3 days per month for a minimum of 3 months.
  • The absence of other signs and symptoms indicating other functional bowel disorders like IBS or functional dyspepsia.

Diet and Lifestyle

As discussed under the causes, there are host of lifestyle factors and physiological causes that may contribute to bloating. This has to be excluded. The difficulty lies in identifying and excluding these factors like carbonated beverages because patients may be untruthful about consuming it. It is therefore advisable to commence dietary changes along with the one or more of the medication below.

  • Avoid carbonated beverages, gum chewing and dairy (lactose intolerance can present with no other symptoms apart from bloating).
  • Eat small meals in moderation. No hurried eating.
  • Seek treatment for nasal congestion and other causes of mouth breathing.
  • Exercise and particularly abdominal firming routines may be helpful.

Dietary modification is also encouraged if a person can identify trigger foods, even is these foods are not considered to be ‘gassy’ or be associated with any intolerance.


There is no specific treatment for functional bloating as the cause is unknown. No specific agent can conclusively be identified to be beneficial to every person with functional bloating but the following should be considered :

  • Probiotics
  • Simethicone
  • Pancreatic enzymes
  • Serotonin agonists

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