Environmental Factors and Ulcerative Colitis: Causes, Risks and More

Several factors, including environmental risk factors, can play a role in triggering flare-ups of ulcerative colitis, during which symptoms return or worsen.

Ulcerative colitis (UC) is a chronic disease that causes inflammation of the colon and rectum.

During flare-ups, people usually experience symptoms such as diarrhea and abdominal pain. A period of remission often follows a flare-up.

Although the exact cause of CU remain unclear, several factors, including environmental ones, can trigger flare-ups and worsen symptoms. By understanding the environmental factors that can trigger a flare, a person may be able to prevent flare-ups and reduce the severity of symptoms.

Dr. Ashkan Farhadi, a gastroenterologist at MemorialCare Orange Coast Medical Center in Fountain Valley, California, spoke with Medical News Today about the different environmental factors and how they can affect people living with UC.

This article also reviews current studies related to environmental factors that may affect a person’s UC symptoms.

A person’s environment can expose them to risk factors that can worsen or potentially cause UC flare-ups.

Although everyone reacts differently, some common environmental triggers include:

  • diet
  • infections
  • pollution exposure
  • stress
  • use of certain medications
  • surgeries


The Crohn’s & Colitis Foundation notes that an infection may be the triggering event that causes UC to develop.

In a 2021 study, researchers found that the rate of common infections, including Salmonella, Campylobacter, and Clostridioides difficileis higher in people with UC.

However, Dr. Farhadi pointed out that although bacterial infections Salmonella and Campylobacter have an association with UC, “we can’t say it’s causal.”

Dr. Farhadi also noted that if a person has a It’s hard infection, they will experience flare-ups that do not respond to treatment. A person will need to receive treatment to get rid of the infection before they can “bring the disease into remission”.

A person should remain alert to signs of infection, especially while using corticosteroids, biologics, or immunotherapies.


Smoking can have many health consequences, but UC does not appear to be one of them. Studies have actually shown weak evidence that smoking can reduce the severity of UC.

Experts don’t fully understand the protective effect of smoking on UC, but nicotine may play a role. According to the Crohn’s & Colitis Foundation, nicotine may protect against UC by:

  • increase mucus production in the colon and rectum
  • suppress the immune system and prevent colon inflammation
  • releasing nitric oxide, which can reduce muscle activity in the colon

According to a 2020 review, transdermal nicotine, or nicotine patches may have some benefit when people with mild to moderate UC use them alongside traditional treatment. However, transdermal nicotine can cause side effects, such as:

  • nausea
  • stunning
  • Difficulty sleeping

Dr. Farhadi noted that “quitting smoking can cause a flare-up of UC, but the benefits of quitting smoking outweigh the risk of flare-ups.”

The health benefits of quitting smoking include:

  • improved overall health
  • increased life expectancy
  • less risk of cancer
  • lower risk of heart disease and stroke

In other words, people who smoke should always consider quitting even if it causes their UC symptoms to flare up.


Certain medications can trigger flare-ups in a person’s UC symptoms. These medications include nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin, ibuprofen (Advil), and naproxen (Aleve). Certain antibiotics can also trigger flare-ups.

Also, people using medications for their UC may have flare-ups if they don’t take them regularly.

lack of exercise

Regular movement can benefit a person’s overall health by many waysand it may also help improve or prevent UC symptoms.

According to Dr. Farhadi, “regular exercise [can help] manage stress. “His advice is to take daily walks”[for a] minimum of 30 minutes, at your fastest pace possible and convenient without jogging.

This type of exercise can boost cardiovascular fitness, manage body weight, improve sleep, and also reduce stress.


Stress can make UC symptoms worse.

Dr. Farhadi said several of his patients have reported psychological stress and flare-ups occurring around the same time. He added that divorce, final exams, job interviews and other stressful events can trigger UC symptoms.

He recommended that people with UC work to improve their stress management to better handle stressful situations. In addition to exercise, he suggested mindful meditation.

Sleep hygiene

Sleep may play a role in preventing or reducing the severity of UC flare-ups.

According to Dr. Farhadi, a person should plan to follow a “constant sleep hygiene” routine at least 6 days a week. This can help minimize UC surges.

Some tips to improve sleep hygiene include:

  • remove all electronic devices from the room
  • sleep in a dark room at a comfortable temperature
  • go to bed and wake up at a regular time
  • avoiding alcohol, caffeine, and large meals before bed
  • participate in regular physical activity

Air pollution

According to a 2019 review of studies, air pollution may play a role in the development of UC. Researchers looked at children’s home environments and noted that children who grew up with constant or regular exposure to air pollutants had an increased rate of developing UC.

Diet and food additives

Dr. Farhadi noted that diet can play a role in helping someone with UC, but he also said that no studies have proven that one diet is better than another when it comes to UC. .

Instead, he suggested people “follow their instincts.” In other words, if a food bothers them, they should avoid it altogether. He also said people who are lactose intolerant may experience flare-ups of their UC symptoms when they consume dairy products.

Some studies also list carbonated drinks as a risk factor for UC flare-ups.

Along the same lines, some people may find exclusion diets help their UC symptoms. To research indicates that many people with UC eliminate troublesome foods.

The study authors don’t recommend any specific exclusion diet, but they do advise people living with UC to eat more home-cooked foods. By doing so, they can avoid food additives, such as sugar and salt, which could cause flare-ups.