Here's Why Constipation Can Cause Nausea — and What to Do About It

Some estimates suggest that nearly one-quarter of adults in the U.S. are affected by constipation. Constipation is a gastrointestinal (GI) condition defined by several symptoms, including pooping fewer than three times per week, stools that are hard, dry or difficult to pass or the feeling that you're not having a complete BM when you do go, per the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).

Surprisingly, "nausea is a really common associated symptom when people have constipation," Rana Abraham, MD, a gastroenterologist at Rush University Medical Center in Chicago, tells LIVESTRONG.com.

When things are just not moving through as they should, you might also lose your appetite, feel bloated or notice abdominal distension, Dr. Abraham says.

So, here's what's going on: One reason you may have constipation is that your colon is slow to move. "With decreased motility in your colon, your whole GI tract may slow, including your upper GI tract, which may manifest as nausea," Dr. Abraham says. In severe cases, this can lead to vomiting.

Another thing that happens: Your GI tract is in communication with its different parts (as well as the brain). If your colon is full of stool, it'll relay a message to your stomach to say, "Hey! We don't need more." There's also a hormonal reflex that happens when you do eat — your stomach then tells your colon to get moving and empty out. But if that move-along process is slow, the whole feedback mechanism can result in nausea.

Other causes of constipation include pelvic floor dysfunction, where the muscles of the pelvic floor, which facilitate going to the bathroom, are not coordinating to correctly relax and contract. "Many people with this issue will have nausea," Dr. Abraham says.

Lastly, constipation can also happen if you have dysbiosis, which is a fancy way of saying that your gut microbiome (you know, the colony made up of trillions of bacteria) is unbalanced. This won't directly lead to nausea but it can cause constipation.

"For people who have a chronic history of constipation, some of the bacteria that normally live in the colon can back up into the small bowel. When these bacteria propagate in the small intestine, you can get small bacterial intestinal overgrowth (SIBO)," Dr. Abraham explains.

Also worth considering: There may be another underlying medical reason that's independently causing both nausea and constipation, such as hypothyroidism (underactive thyroid function), Dr. Abraham adds. It's possible that you can also have constipation and indigestion and it's the indigestion that's contributing to nausea, she says.

First, you'll want to know ‌why‌ you're experiencing constipation, and that can be tough to pin down on your own. Just 37 percent of people who have constipation speak to their doctor about it, according to ‌The American Journal of Gastroenterology‌.

But communicating with a health professional can be important: For example, if you have pelvic floor problems, then some of the at-home remedies for constipation mentioned below won't address the underlying issue at play.

A few places to start for constipation include ramping up fiber and water intake and getting the right amount of sleep. Preliminary research, presented at Digestive Disease Week in 2020, found that rates of constipation were lowest in adults who get seven to eight hours of sleep per night. Sleeping less than that increased the risk of constipation by 38 percent, while people who slept for longer had a 61 percent higher risk.

As for fiber, Dr. Abraham suggests increasing the amount you consume by tracking your fiber intake during the day via a calorie-tracking app or program. (Try this for a few days.) With tracking, you'll see what foods you normally eat that are the most fiber-rich — and you can focus on eating more of those foods.

Dr. Abraham says it's a lot more intuitive to do it this way rather than focusing on, say, trying to eat a ton of broccoli if you're not into the veg. You should aim for 25 to 38 grams of fiber every day. Taking a fiber supplement, like Metamucil ($17.91, Amazon.com), which contains psyllium husk, can help by drawing water into the colon to make it easier to pass.

If the above measures don't help, or constipation is a sudden and new symptom for you, make that appointment with your doctor. Unfortunately, for nausea, there's not much you can do. Some people find that sipping ginger tea can help settle their stomach, which is safe to try, Dr. Abraham says. Otherwise, focus on improving regularity to relieve the discomfort of constipation and nausea.