This informational guide, part of PS's Condition Center [1], lays out the realities of this health concern: what it is, what it can look like, and strategies that medical experts say are proven to help. You should always consult your doctor regarding matters pertaining to your health and before starting any course of medical treatment.

Social media is flooded with banter poking fun at the "connection" between physical attractiveness and stomach issues [2]. But if you have abdominal pain, gas, and/or diarrhea or constipation [3] that lasts more than three months, it may be caused by irritable bowel syndrome, and you know it's not a joke.

This common, but uncomfortable disorder affects the large intestine. "It's the most common GI condition gastroenterologists see and one of the most common seen by primary-care doctors," says Shanti Eswaran, MD [4], a gastroenterologist at the University of Michigan Health System. IBS can have a negative impact on your life, but most people can get control of their symptoms with appropriate treatment. Ahead, we break down everything you need to know about IBS, including IBS symptoms, what causes IBS, and how IBS is treated.

Experts Featured in This Article:

Shanti Eswaran [5], MD, a gastroenterologist at the University of Michigan Health System.

What Is IBS?

"Irritable bowel syndrome (IBS) is a common disorder that affects the stomach and intestines, also called the gastrointestinal tract," per the Mayo Clinic [6]. As many as 15 percent of adults in the US have IBS, most of them under 50, and it affects about twice as many women as men, according to the American College of Gastroenterology [7]. The classic signs are belly pain associated with a change in bowel-movement frequency and consistency, plus an increase in gas and bloating.

"There are three IBS subtypes: diarrhea predominant, constipation predominant, or a mix of both," Dr. Eswaran says. "The constipation type is more common in women, whereas diarrhea is more common in men, but people can flip-flop over the years. And some people alternate between diarrhea and constipation from week to week."

IBS Signs and Symptoms

Some of the most common signs of IBS, per the Mayo Clinic, include:

• Abdominal pain, cramping, or bloating related to passing a bowel movement
• Changes in bowel movement appearance
• Changes in frequency of your bowel movements
• Increased gas and bloating
• Feeling like you haven't completely passed your bowel movement

While IBS can be disruptive, it isn't typically dangerous. Many people are able to manage it through lifestyle changes alone. But it's important to see your doctor to rule out a more serious condition, especially if you have additional symptoms, such as diarrhea at night, bloody stool, or unexplained weight loss.

What Causes IBS?

"[IBS is] driven by different factors in different people," Dr. Eswaran notes. The following issues are all possible causes.

• A severe bout of diarrhea caused by a bacteria or virus can set off IBS in some people.
• A family history of the disorder may make you more susceptible, too, so genes likely have an impact.
• Brain-to-gut miscommunications. The nerves in your brain and your gut "speak" to one another, and one theory is that IBS occurs when those signals get thrown off. Your brain might become overly sensitive to normal goings-on in your GI tract, for instance, causing pain, according to the Mayo Clinic.
• Irregular intestinal muscle contractions, which are meant to move food through your digestive tract. "When they're too fast or strong, they can cause diarrhea; too slow or weak, they can cause constipation," the Mayo Clinic notes.
• Increased sensitivity to certain foods, stress, and hormones may be part of the problem for some people, Dr. Eswaran says. People can become more sensitive to these things with age or due to a change in environment.
• The gut microbiome — the trillions of microbes that live in a specific pocket of the large intestine — is often dysregulated in people with IBS as well. But it's unclear which came first: the imbalanced microbiome or the IBS, Dr. Eswaran notes.
• Trauma has also been linked to IBS, Dr. Eswaran says. Research has shown [8] that "trauma may sensitize the brain and the gut," as stated in a press release from the American College of Gastroenterology regarding a trauma and IBS study.

As for why women are more likely than men to be affected, there are a couple of theories. For one, "women are more likely to seek medical help regarding IBS symptoms compared to men, who tend to under-report their symptoms," according to Weill Cornell Medicine [9]. On top of that, clinical trials for IBS tend to include more women than men, which may cause study bias or an overestimation of prevalence among women. But factors like hormones and gut motility may also come into play. (Note: these studies didn't specify between cisgender, nonbinary, and transgender people.)

How Is IBS Diagnosed?

Doctors typically diagnose IBS by ruling out other conditions that could be causing stomach issues, such as celiac disease [10], and assessing a person's symptoms. A stool test, colonoscopy, or CT scan, among other things, may be used to narrow down the potential condition, per the Mayo Clinic. As many as 70 percent of people [11] with symptoms of the disorder won't ask their doctor for help, though. "It's important to bring your symptoms to the attention of your doctor, because the majority of people with IBS have mild to moderate symptoms that respond well to lifestyle and diet modifications," Dr. Eswaran says. Going undiagnosed means missing out on a potentially simple solution.

How Is IBS Treated?

IBS treatment is as varied as its causes. "If a patient says, 'Eating makes my symptoms worse,' we do an elimination diet to help identify which foods are problematic," Dr. Eswaran says. For instance, carbonated beverages can increase gas in some people, while others are sensitive to certain carbohydrates, like fructose and lactose. If constipation is your predominant problem, your doctor might recommend fiber supplements and laxatives. If diarrhea is the issue, over-the-counter antidiarrheal medications can help.

Most people with IBS benefit from managing stress, exercising regularly, and getting enough sleep, all of which can help calm and regulate the bowel. But when those approaches don't work, there are also a variety of medications designed to treat the condition. Additionally, "regardless of the type of IBS, antidepressants — both selective serotonin reuptake inhibitors and tricyclics — can be helpful, because they affect the nerves of the GI tract," Dr. Eswaran says.

Ultimately, she says, "There's no cure. But almost everyone can feel a lot better."

Ginny Graves [12] is an award-winning writer in the San Francisco Bay Area whose work focuses on science, psychology, health, nature, and the human-animal bond. In addition to PS, her features have appeared in Time, Vogue, Runner's World, Men's Health, O The Oprah Magazine, Elle, Prevention, Scientific American, and National Geographic Adventure.