The answer could shed light on what causes these conditions. But that answer is proving hard to get.
Fibromyalgia is a common condition that causes painful muscles. The pain is severe and involves many muscles as well as tendons, ligaments, and other soft tissue areas. Fibromyalgia has also been linked to fatigue, sleep problems, headaches, cognitive dysfunction, depression, and anxiety.
Irritable bowel syndrome (IBS) is a disorder that involves abdominal pain, cramping, bloating, as well as changes in bowel movements - constipation or diarrhea, or alternation of both. People with IBS often experience anxiety and depression.
Millions of people have at least one of these conditions. Fibromyalgia affects 5 million U.S. adults, and an estimated 25 million to 45 million people in the U.S. have IBS.
If you have fibromyalgia or IBS, you may be more likely to have the other one, too.
In one study, 32% of people with IBS also had fibromyalgia symptoms, compared with 4% of people without IBS. Another study showed fibromyalgia occurring in 20% of people with IBS. And studies have estimated 32% to 70% of people with fibromyalgia also meet criteria for IBS.
Linked but Separate
The root causes of fibromyalgia and IBS are not clear. And why they often overlap isn't known, either.
Both are functional disorders. There isn't anything wrong with the structure of the organs, but with how they work.
Fibromyalgia and IBS don't always go together. They're two separate conditions.
But there is relationship between two, says Michael J. Pellegrino, MD, a fibromyalgia expert at Ohio Pain and Rehab Specialists in North Canton, Ohio and an expert on WebMD's Fibromyalgia Exchange. Pellegrino, who has fibromyalgia, says he also has intermittent IBS that he considers mild.
"There's some connection because they come in clusters, but we don't know what it is right now," says Albena Halpert, MD, an assistant professor of gastroenterology at Boston University's medical school.
Researchers see a possible pain link between IBS and fibromyalgia. In short, people with those conditions respond to pain differently than people without the two conditions.
It's been also found that people treated with a certain group of antidepressants, known to affect when pain is felt by someone, for both conditions responded favorably. This led to the idea that the disorders were possibly linked by a similar underlying cause.
In fibromyalgia, the central nervous system may be highly sensitive, making someone feel more pain than what someone without fibromyalgia would feel in a similar situation. And the central nervous system is not as able to block or inhibit the pain compared to someone without the condition, Pellegrino says.
In IBS, someone has the urge to pass a bowel movement that is often associated with bowel cramping, and the body fails to curb those pain signals. Similarly, a very mild trigger -- such as certain foods that don't bother most people -- can result in cramping someone with IBS, Halpert says.
Both conditions can drastically hamper daily life. For instance, someone with IBS may have to rush to bathroom after the abdominal pain begins. The symptoms can last a couple of hours to a day at a time, she says.
"We can't figure out how to shut the pain signals off, whether it's IBS or fibromyalgia. It's the continuous and overwhelming signals that can't be handled," Pellegrino says.
Pellegrino likens fibromyalgia's pain issue to a garden hose with a nozzle.
"The water flow is like a nerve signal and you can squirt the water and control it," he says. "The nozzle is preventing all of the water from getting through. Half of it is already being blocked by the nozzle. For those with fibromyalgia, that water just flows through. You can't block the flow of pain."
There are treatments for IBS and fibromyalgia. They can include medications and/or lifestyle changes that address symptoms.
The key, Pellegrino says, is learning how to manage these conditions and how to deal with the stigma that may come with them. Talking with your doctor and finding a support group may help.
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