Bloating and Distension in IBS

Bloating and abdominal distension, which can affect anyone, are especially common with irritable bowel syndrome (IBS), and they can be among the most persistent symptoms of the condition.

Bloating

Bloating is defined as the perception of increased pressure in the abdomen. Bloating is a fairly universal phenomenon, reported more frequently by females than males, with an estimated 16 to 31% of the general population experiencing it at some point.

Up to 90% of people who are diagnosed with IBS report bloating, and the percentage is even higher for those with constipation-predominant IBS (IBS-C).

While it's most common in IBS-C and mixed-type IBS, about half of those with diarrhea-predominant IBS (IBS-D) experience it, too.

However, bloating isn't listed as part of the Rome IV criteria for diagnosing IBS.

Distension

Distension differs from bloating in that it involves a measurable change in abdominal circumference (the measurement around your waist at the largest part).

Distension typically worsens as the day wears on. You may also find that your abdomen gets more distended after you have eaten.

It's estimated that approximately half of all people who have IBS experience distension. Distension and bloating often occur simultaneously, but it is thought that they result from different bodily processes.

Causes

Studies show that excessive gas is responsible for about 25% of the bloating associated with IBS and other functional gastrointestinal (GI) disorders.

Several underlying mechanisms are being investigated as possible causes of bloating in IBS. It's possible that many of them are interrelated.

Some possible underlying mechanisms include:

• Disruption of the brain-gut axis: A complex interaction between the brain and gut bacteria suggests that psychological stress can impact the balance of bacteria and vice versa.
• Increased intestinal permeability ("leaky gut"): Improper function of the intestinal lining may allow bacteria and small molecules of partially digested food to leave the digestive system, trigger inflammation, and interfere with the balance of gut bacteria.
• Intestinal immune activation: Low-grade inflammation may be due in part to abnormal activity of the immune system.
• Visceral hypersensitivity: People with this problem tend to feel bloated and have other symptoms when the digestive system is only mildly irritated. It usually occurs without distension.
• Gastrointestinal dysmotility (impaired movement): This causes gas to get trapped in the first and middle parts of the colon.
• Impaired abdominal wall response to pressure: This occurs with chronic bloating and distension, as the reaction of the diaphragm and abdominal wall muscles to pressure from gas is the opposite of what it should be.

Evidence also suggests that bloating may especially be a problem for people who have other digestive issues in addition to IBS.

These include:

• Food intolerances: Often, malabsorption due to food intolerance leads to fermentation, which increases gas production.
• Small intestine bacterial overgrowth (SIBO): Excess levels of some bacteria may be responsible for carbohydrate fermentation.
• Bacterial imbalances: Some healthy bacteria in the digestive tract may decline, which can slow digestion.

People who have IBS-C are more likely to have bloating and distension if it takes longer for digested material to travel through the colon.

IBS Symptom Relief

Bloating is a notoriously difficult symptom to treat. However, you do have several options to explore to get rid of bloating.

IBS is different for everyone, so expect to do a lot of experimentation before you find what works best for you, and try not to get frustrated when your experience doesn't match that of other people with this condition.

IBS Medications

No treatments are definitively proven to improve bloating in IBS. Common drugs that doctors may recommend include:

• Antispasmodic drugs, including Menoctyl (otilonium) and Bentyl (dicyclomine), may help calm spasms in the intestinal walls that can trap gas
• Antidepressants to help correct the brain-gut dysfunction, including tricyclics (TCAs) and selective serotonin reuptake inhibitors (SSRIs)
• Prosecretory drugs, a kind of prescription laxative, including Linzess (linaclotide) and Trulance (plecantide)
• Viberzi/Truberzi (eluxadoline), which alters the activity of certain cell receptors in the nervous system and improves symptoms of IBS-D
• Serotonergic agents such as Lotronex (alosetron), as the hormone/neurotransmitter serotonin is involved in digestive motility, sensation, and secretion
• Antibiotics, which may be helpful for those with SIBO, including Xifaxan (rifaximin) and Biaxin (clarithromycin)
• Bulk laxatives, available over-the-counter (OTC), to help you expel gas and feces
• Gax-X (simethicone), an OTC medication that can help you eliminate gas

Other IBS Treatments

While medications may help, they may not alleviate all of your symptoms. Many people with IBS include other types of treatments in their regimen, including:

• Dietary changes, especially a low-FODMAP diet or elimination of trigger foods
• Probiotic or prebiotic supplements, which may help balance gut bacteria
• Peppermint oil, which is a natural antispasmodic (see warning below)
• Psychological therapies including cognitive behavioral therapy, relaxation therapy, and hypnotherapy
• Exercise and physical fitness, which studies show may help ease symptoms

While they've received less scientific attention than other types of treatments, some evidence supports the use of mind-body treatments for IBS.

Frequently Asked Questions

What relieves IBS bloating?

Peppermint tea may provide some immediate IBS relief along with relaxation and exercise. Treatments that may help over the course of several weeks include Linzess (linaclotide), probiotics, and antibiotics. Long-term relief, though, may require dietary changes and efforts to avoid constipation. 

Why does IBS make my belly swell?

Constipation is the most common cause of IBS-related belly swelling, known as distension. This often results from problems with the function of gastrointestinal nerves and muscles. You may also experience bladder hypersensitivity, which causes abdominal swelling.

How long does an attack of IBS bloating last?

An IBS flare-up typically lasts two to five days. In addition to bloating, you might experience constipation or extreme diarrhea, cramping, and emotional symptoms such as anxiety.