What Causes Bloating—and What to Do About It

Bloating is an uncomfortable feeling of fullness or pressure in the abdomen. Like an overinflated balloon, a bloated belly can feel packed with air, and in some cases may be visibly enlarged or distended.

Bloating is a common issue. By some estimates, up to 30% of Americans experience it from time to time. In a majority of cases, the sensation is temporary and tolerable. It may not be pleasant, but on its own it’s usually not cause for serious concern. However, bloating can also be a symptom of an underlying gastrointestinal problem or disorder, including some issues that warrant a medical provider’s urgent attention.

“If bloating is negatively impacting a patient’s quality of life, we should investigate it and treat it,” says Dr. Kimberly Harer, a gastroenterologist and clinician at the University of Michigan Health System. That’s especially true if a person’s bloating is accompanied by additional red-flag symptoms, which may indicate a potentially serious medical situation.

Here, Harer and other experts explain the common causes of bloating, including food triggers and GI disorders. They describe some of the more mysterious aspects of the condition, and detail the most effective treatment options.

What causes bloating?

The list of potential causes is long. At the top of that list is anything that causes a buildup of gas in the intestinal tract, which can cause sensations of bloating throughout the stomach and abdomen.

“There are two major contributors to this kind of bloating,” says Dr. Scott Gabbard, a gastroenterologist at the Cleveland Clinic. The first is dietary. “You may be eating foods that are fermented in the gut and produce a lot of gas,” he explains. While a wide range of foods can cause gassy buildup, he highlights a group known as FODMAPs, which is an acronym for fermentable oligosaccharides, disaccharides, monosaccharides, and polyols. These are short-chain carbohydrates that are difficult for the gut to digest, and therefore more likely to migrate down to the large intestine, or colon, where they’re often broken down into gaseous byproducts. Beans and other legumes, as well as cruciferous vegetables like broccoli, are examples of high-FODMAP foods.

The second major cause of gas production, Gabbard says, is caused by some sort of imbalance within the gut’s community of microorganisms, a.k.a. the gut microbiome. “You may have too much or too little of certain bacteria, or you may have the wrong types of bacteria,” he explains. For example, some of his recent work has found that patients with small intestine disorders may have higher levels of a group of gut bacteria known as methanogens, which make methane gas. “They may also slow down the entire digestive system and produce constipation, which can contribute to bloating,” he says.

Another type of microbiome imbalance is called SIBO, which stands for small intestine bacterial overgrowth. “Normally, very few bacteria live in the small intestine,” says Dr. Brian Lacy, a GI expert and professor of medicine at the Mayo Clinic. “Patients who have small intestinal bacterial overgrowth have too many bacteria living in the small intestine.” These bacteria process food sooner than usual, which can cause symptoms of gas and bloating.

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Gastrointestinal transit disorders—problems with the way food, mucous, and other material move through the GI tract—could also be a factor. “Two of the most common disorders associated with gas and bloating are chronic constipation and irritable bowel syndrome with constipation,” Lacy says. Whenever the contents of the gut aren’t moving through it properly, gas can become trapped, which can cause bloating.

Gas and bloating often go hand in hand, but that’s not always the case. In fact, Gabbard says that many people who experience bloating don’t have abnormally high levels of gas. “When investigators have looked at the amounts of gas in the intestine and compared healthy volunteers to patients who experience bloating, they’ve usually found no difference in gas production,” he says. “Many of the patients who come to us with complaints of bloating end up having overly sensitive nerves in the gut, so the amount of gas is the same but they feel it more.” This is sometimes referred to as visceral hypersensitivity, and it’s typical of irritable bowel syndrome (IBS).

A variety of medical issues can also cause bloating, including problems with the way the muscles of the stomach stretch and relax to accommodate food. “When someone tells me the top of their stomach feels full and bloated immediately after a meal, and that they can’t eat as much as they used to, this points to a disorder called functional dyspepsia, where the stomach is not relaxing,” Gabbard says. It’s also possible for the muscles of the intestine to relax or stretch inappropriately during digestion, which can lead to bloating and distension.

Over and over again, GI experts stress that bloating is a complex issue with many (potentially overlapping) triggers. Determining the precise cause or causes of a person’s bloating—a necessary step in identifying appropriate treatment—is something best done with a medical provider’s help.

Read More: The Best and Worst Foods for Bloating

Can bloating become a serious health issue?

By itself, bloating can be severe enough to make life difficult. “Unfortunately, bloating isn’t always considered a significant complaint by health care providers, and it’s brushed aside,” Harer says. “People suffer in silence.” That said, bloating by itself is usually not a symptom of a life-threating medical condition. “When it’s accompanied by red-flag symptoms—vomiting, blood in stool, unexplained weight loss, yellowing of eyes or skin—those are signs of a more urgent and serious disorder,” she says. Liver disease or an obstruction of the GI tract can cause bloating accompanied by some of these red-flag symptoms.

In rare cases, bloating can also be a symptom of ovarian cancer. “But we need to put that statement in perspective,” Lacy says. Tens of millions of people experience bloating each year, and most—over 99%—don’t have ovarian cancer. “Bloating is a very nonspecific symptom”—meaning it’s associated with a wide range of causes—“and I do not consider it a warning sign of ovarian cancer if it is the only symptom,” he says. (Other symptoms include weight loss, fatigue, feeling full quickly when eating, frequent urination, and discomfort in the pelvic area.)

What is the relationship between bloating and periods?

“Many women, especially in the week before or during their menstrual cycle, will notice some increasing bloating that often abates in the week following their menstrual cycle,” Harer says. Why this happens isn’t well-understood, but she says that hormonal factors could be at play.

Variations in reproductive hormones during a woman’s cycle may influence both gut motility (movement of stuff through the GI tract) and gut sensitivity, which could lead to bloating. Hormone fluctuations (specifically shifting levels of estrogen and progesterone) can also lead to water retention, which can cause sensations of fullness and bloating. Lacy says approximately 70% of women report bloating during their menstrual cycle, and many are actually able to differentiate the sensations of bloating during their cycle: some can tell which symptoms are due to diet and which are from constipation, for example. “This again highlights how complex bloating is,” he adds.

What are the best and worst foods for bloating?

Experts again highlight FODMAPs, those short-chain carbohydrates, as typical bloating triggers. “As a group, these foods generally produce more gas than other foods,” Lacy says. Some examples of high-FODMAP foods are dried fruits, apples, mangoes, pears, plums, honey, onions, peppers, garlic, cruciferous vegetables (broccoli, cauliflower), legumes, and anything that contains artificial sweeteners, such as “sugar-free” candies, gums, and mints.

Lacy says that lactose (a type of sugar found in dairy foods) and fructose (a type of sugar found in fruits and sweets) can also cause gas and bloating. “Common offenders are liquids that contain fructose or high-fructose corn syrup, including juice, sports drinks, energy drinks, and sodas,” he says.

If a person’s bloating appears to be caused by dietary factors, a health care provider is likely to suggest a special diet. “The diet has two phases—a restriction phase and a reintroduction phase,” Harer explains. The restriction phase is likely to involve cutting out all high-FODMAP foods, and maybe also dairy products, wheat products, and carbonated drinks (which can produce gas and bloating.) Ideally, avoiding all these foods will relieve a person’s bloating. At that point, each food may be added back in, one at a time, so the person can figure out the sources of their bloating symptoms. “The goal is not to keep someone on that severely restricted diet indefinitely,” Harer says. “The goal is to identify which foods and which amounts are triggers, so they have the power to determine how much of those foods they want to eat.”

She strongly recommends that people attempt this approach only with the assistance of a registered dietitian. Restriction diets are complicated and easy to mess up, and cutting out these foods can lead to dangerous nutrient shortfalls. Harer adds that if an elimination diet relieves a person’s bloating, this does not suggest the person has a food allergy. Bloating and gas are not inherently harmful, she says, and eating foods that cause them is not damaging to a person’s GI system. “You’re not hurting yourself if you eat foods that give you gas or bloating,” she adds.

The list of foods that relieve bloating is much shorter. Green kiwifruit is one of the very few foods that research has linked to symptom improvements. “I’ve had some patients with bloating and constipation eat two green kiwifruits per day, and the response has been tremendous,” Gabbard says. Green kiwifruit contains a compound called actinidin that may enhance digestion and calm gut inflammation.

There’s major interest in using probiotic or prebiotic foods to treat bloating. “You hear a lot about kimchi and sauerkraut, and foods like yogurt that contain bacteria,” Harer says. But so far, the research on their usefulness in treating bloating has been mixed.

Read More: 5 Sneaky Causes of Bloat and How to Avoid Them

What relieves bloating?

Apart from identifying and avoiding food triggers, other remedies may be helpful. These include both over-the-counter supplements (like peppermint oil and magnesium) and prescription drugs.

Relaxation and stress-reduction techniques have also been shown to relieve a variety of gut symptoms, including bloating. Stress can cause heightened immune system activity and inflammation, so it makes sense that targeting stress (and the thoughts that give rise to it) could provide relief. Gabbard mentions diaphragmatic breathing (belly breathing), cognitive-behavioral therapy, and acupuncture as three potentially helpful treatments. “Several of these therapies have been shown to be more effective than most medications for irritable bowel syndrome,” he says.

The right treatment plan will depend on the specifics of a person’s bloating. “Oftentimes there are multiple contributing factors,” Harer says. “It can take some trial and error to identify the causes and best remedies.”