7 Common Crohn’s Triggers
Updated on January 28, 2026
Crohn’s disease, an inflammatory bowel disease (IBD) that can affect any part of the gastrointestinal (GI) tract, is a chronic condition that follows a relapsing-remitting pattern. This means that those with the illness typically experience alternating periods of few or no symptoms (remission) and symptomatic episodes, or flares (relapses), which can be triggered by a variety of factors.
To increase your odds of staying in remission, you’ll need to avoid your personal Crohn’s triggers. Read on to learn about some of the most common ones.
1. Stress
Stress can lead to flares in some people living with Crohn’s, says R. Balfour Sartor, MD, a gastroenterologist and professor of medicine, microbiology, and immunology at the University of North Carolina School of Medicine in Chapel Hill.
Even in people who don’t have Crohn’s, stress can stimulate contractions in the intestines, leading to diarrhea, cramping, and nausea. With Crohn’s disease, you are already susceptible to cramping and diarrhea, so these symptoms can be even worse. “Beyond that, there is some evidence that stress can stimulate inflammation and activate disease activity,” says Dr. Balfour Sartor.
2. Smoking
Smoking cigarettes can trigger flares and symptoms in Crohn’s. It’s not yet clear why smoking exacerbates inflammation in Crohn’s, but preliminary research suggests that it may be connected to a smoking-related change in the bacteria that line the gut (the microbiome).
One study, which used cell cultures to examine the effects of nicotine in people with IBD, found that bacterial infections may be responsible for an inflammatory response in smokers with Crohn’s.
In addition to exacerbating Crohn’s inflammation and related symptoms, smoking is connected with more severe illness overall, complications (including those that require surgery), postsurgical flares, symptoms outside the gut (extraintestinal manifestations), and an increased risk of bowel cancer. Smoking can also reduce the effectiveness of certain IBD medications, making all of the above more likely.
It’s strongly recommended that people with Crohn’s avoid starting or quit smoking. In people who quit, risk factors are reduced to roughly the same level as people with the illness who have never smoked at all. A research review on Crohn’s and smoking cessation wasn’t able to determine whether any particular behavioral or medication-based method was superior; speak with your doctor about which one might best suit you if you’re trying to quit.
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3. Medication
Some medications — including nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin and ibuprofen (Advil, Motrin) — and certain antibiotics and other antimicrobials can trigger Crohn’s flares in some people. The jury is still out on NSAID use, however, with newer data suggesting less of a direct connection between NSAID use and flares than previous research had found. That said, people with Crohn’s are still advised to use caution with NSAIDs.
A study on antibiotics and other antimicrobial medications found that several were strongly connected with flares in Crohn’s, though the authors write that they could not prove the drugs were the cause. Antibiotics in the quinolone class, such as ciprofloxacin (Cipro); drugs used for amoeba and protozoa infections, including metronidazole (Flagyl); antifungals like fluconazole (Diflucan); and other intestinal anti-infection medications such as nystatin (Bio-Statin) were all connected to a greater risk of flares in the study.
If you’re concerned, talk to your doctor about the potential risk of using such medications and whether you should consider alternatives. There’s no guarantee that these drugs will be a problem for you, and in the case of medications used to fight serious infections, it may be worth a hypothetical risk.
Antibiotics change the balance of bacteria in the gut, which can activate diarrhea, even in people who don’t have Crohn’s, says Balfour Sartor.
4. Diet
While there’s little research to back up the idea that diet or specific foods are the cause of flares, many with Crohn’s find that food can trigger symptoms, particularly when you’re already experiencing a flare. No one food will cause symptoms in everyone, so you should track your diet to determine the culprits.
In general, you may want to avoid foods that can increase gas or trigger diarrhea, such beans, cabbage, spicy foods, carbonated drinks, and greasy, fried foods. It’s also a good idea to stay away from raw vegetables, seeds, nuts, and popcorn if you are among those with Crohn’s disease who have strictures (a narrowing of the intestines), which increases the risk of an obstruction, says Balfour Sartor.
Unfortunately, there’s no definitive proof that diet can cause or prevent flares in Crohn’s, and doctors are not yet able to make recommendations on what you should specifically eat or avoid. In most cases, people with IBD are advised to eat a healthy, well-balanced diet and steer clear of processed foods.
According to research, a Mediterranean diet — which includes the healthy fat from olive oil and fiber from whole grains — has been shown to improve Crohn’s symptoms, inflammation, and quality of life.
5. Infection
Infections can precipitate flares, says Balfour Sartor. “We know that gut infections can kick off symptoms in patients whose symptoms had been [in remission],” he says.
One possible Crohn’s flare trigger is a Clostridioides difficile (C. diff) infection. People with IBD are more likely to contract a C. diff infection than those without IBD, and they may experience more serious illness. “That’s probably the most significant infection that we see for flares,” says Kelly Cushing-Damm, MD, a gastroenterologist who specializes in IBD and an assistant professor of internal medicine at the University of Michigan Medical School in Ann Arbor.
Taking antibiotics may increase the risk of C. diff. “If someone with Crohn’s develops worsening symptoms after a recent course of antibiotics, that would lead us to think about this particular infection,” says Dr. Cushing-Damm.
Cytomegalovirus (CMV) is another virus that may trigger Crohn’s flares, says Cushing-Damm. “CMV tends to be a higher risk for patients who have been immunosuppressed for a period of time, such as patients on steroids.”
6. Seasonal Changes
If you suspect that some flares are triggered by seasonal changes, according to research, you may be right. “One theory is that it might have something to do with an allergy to pollen or exposure to respiratory infections,” says Balfour Sartor.
Another research review notes that spring and summer saw a slightly higher share of IBD hospital admissions, while those admitted in fall and winter had higher rates of intestinal obstructions than people admitted at other times. The paper’s authors note that there wasn’t a seasonal difference in mortality rates or in the length of hospital stays, however.
Because research is in preliminary stages, experts haven’t narrowed down what may be causing seasonal influences on flares. This means you’ll need to include potential triggers in a symptom diary or smartphone app to track symptoms. This might include logging dietary changes, infections, sleep alterations, or periods of extreme weather to see if they’re associated with flares.
7. Not Taking Your Medication
If you’re experiencing side effects or other problems that are interfering with your ability to take your medications as directed, you could experience a flare as a result. In that case, it’s important to work with your doctors to find a solution, says Cushing-Damm.
Indeed, research connects not taking IBD medication as prescribed with an increased risk of flares, complications, hospitalizations, disease progression, and poorer quality of life. What’s more, not taking medication properly — particularly biologics and small-molecule drugs — can affect how well they work. These medications require maintaining high enough levels to treat the illness and to avoid developing immune antibodies that work against them, which can make the drugs less effective.
Poll
Which of these has been the biggest trigger of your Crohn's flares?
The Takeaway
- Crohn's disease, a form of inflammatory bowel disease, is characterized by alternating periods of remission and relapse (flares); learning to identify and avoid flare triggers can help you manage the illness.
- Commonly reported triggers for Crohn's flares include stress, smoking, certain medications, specific foods, infections, and seasonal changes.
- One of the most consequential triggers is not taking medication as prescribed, which can lead to flares, complications, and reduced treatment effectiveness.
- To identify triggers, it's recommended to track symptoms and potential causes, and avoidance strategies include stress reduction, smoking cessation, and using alternatives to NSAIDs.
EDITORIAL SOURCES
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Yuying Luo, MD
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Yuying Luo, MD, is an assistant professor of medicine at Mount Sinai West and Morningside in New York City. She aims to deliver evidence-based, patient-centered, and holistic care for her patients.
Her clinical and research focus includes patients with disorders of gut-brain interaction such as irritable bowel syndrome and functional dyspepsia; patients with lower gastrointestinal motility (constipation) disorders and defecatory and anorectal disorders (such as dyssynergic defecation); and women’s gastrointestinal health.
She graduated from Harvard with a bachelor's degree in molecular and cellular biology and received her MD from the NYU Grossman School of Medicine. She completed her residency in internal medicine at the Icahn School of Medicine at Mount Sinai, where she was also chief resident. She completed her gastroenterology fellowship at Mount Sinai Hospital and was also chief fellow.
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Katherine Lee is a writer and editor who specializes in health, science, and parenting content. She has written for Verywell, where she covered school-age parenting, and worked as an editor at Parenting and Working Mother magazines. She has written and edited numerous articles and essays on science, parenting, and children's health and development for What to Expect, the American Association for the Advancement of Sciences, the American Psychological Association, and Newsweek, among others