IBD and the Flu

People with Crohn's or ulcerative colitis risk flu complications

Inflammatory bowel diseases (IBDs) are lifelong, chronic conditions for which there is currently no cure. IBD is an umbrella term and the diseases that fall under it include Crohn's disease, ulcerative colitis, and indeterminate colitis. These diseases are complex and the symptoms can range from being mild to severe.

IBD is thought to be caused by an overactive immune system. For that reason, these diseases are often treated with drugs that dampen the immune system. This is why other types of illnesses, like influenza (the flu) can become serious for people who live with IBD. This article will address the various complications that might occur in people with IBD who develop the flu.

Flu Complications When You Have IBD

Verywell / Nusha Ashjaee

Cause and Treatment of IBD

The cause of IBD is known to be complex and it's not yet well understood. It may be the result of having been born with the genes that are connected to IBD and then the immune system being "triggered" by something in a person's environment. This causes the immune system to treat the digestive system as if it were a threat to the body.

The digestive system is attacked, leading to inflammation in the intestines and other signs and symptoms. This is why IBD is often referred to as an autoimmune condition, or, more recently, as an immune-mediated condition.

Although the signs and symptoms of IBD mainly affect the digestive system, the entire body can be involved in various ways. People with IBD can also have problems outside their digestive system (called extraintestinal manifestations). Like the disease itself, these issues can be mild or they can be severe.

This is why IBD is often treated with medications that suppress certain aspects of the immune system. The inflammation that's caused by the IBD can be treated by getting control over the overactive immune system. 

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Immune Suppression Unintended Effects

While taking a medication that slows down the immune system may help manage the IBD, there can be unintended effects. The immune system protects the body from all kinds of harm. This can include everything from the common cold to more serious conditions like pneumonia.

The drugs that are used to treat IBD are in different classes and they work in various ways. Some of these medications can affect the immune system broadly and others are more targeted, only altering specific inflammatory pathways.

With the immune system working differently as a result of medications, it may not be as effective in dealing with common infectious diseases. One of these is the flu, which can be more serious and severe in people who have IBD. 

Complications From the Flu

The flu is often thought of as a seasonal illness that doesn't pose much danger and that most people recover without any lasting effects. However, people with IBD may be at an increased risk of complications from the flu.

Risk of Contracting the Flu

People with IBD may be more likely to get sick with the flu than healthy people. A study of people with IBD and the flu was done using information from a large health claim database. The people included in this database had commercial insurance coverage.

More than 140,000 people who had a form of IBD were compared with the same number of people who were healthy controls. Those with IBD were more likely to have gotten the flu than the healthy group. This was especially true amongst younger people, those between 18 and 20 years old in particular.


The rates of hospitalization after having the flu were also compared in the study that used the large health claim database. When compared to the healthy group, people with IBD had more hospitalizations within a month of having the flu. The IBD group who had the flu were hospitalized at a rate of about 6%, compared to about 2% of those who didn't have IBD.


One of the chief and most dangerous complications from having the flu is developing pneumonia. With pneumonia being a potential complication of the flu, it is important that people with IBD avoid getting sick with the flu in the first place.

Another study using data from a large health claim database looked at more than 100,000 people with IBD and compared them to 400,000 healthy people. What this study showed was that people with IBD are already, at baseline, at an increased risk of developing pneumonia.

The risk is particularly increased for those also taking corticosteroids and moderately increased for those who were receiving anti-tumor necrosis factor medications such as Remicade (infliximab), Humira (adalimumab), or Cimzia (certolizumab pegol).

Other Complications of the Flu

Having the flu puts even healthy people at risk of developing many different conditions. People with IBD may or may not be at greater risk of having other complications, which will depend largely on the course of the IBD and any extraintestinal manifestations.

Some of these complications include inflammation of tissues in the heart (myocarditis), brain (encephalitis) or muscles (myositis or rhabdomyolysis); multi-organ failure (such as respiratory and kidney failure); and a life-threatening result of an infection called sepsis.

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IBD and Steroid Medications

Corticosteroids are commonly used to treat IBD as well as many other inflammatory conditions. Sometimes they are used for a short period of time but in other cases, they are taken long-term. It's generally now understood that corticosteroids such as prednisone put patients at risk for a number of potential complications and adverse effects.

For this reason, IBD specialists now recommend that people with IBD only receive these drugs for the shortest period of time possible. A goal of treatment should be to move to medications that can control the IBD while having fewer side effects. Taking these medications has been shown to increase the risk of contracting the flu in people who have IBD.

How to Avoid the Flu

Most healthy people who come down with the flu will feel better between a few days to a few weeks. However, it may be a different situation for people who have a chronic illness like IBD. The symptoms of the flu can include:

  • Chills
  • Cough
  • Fatigue
  • Fever
  • Headache
  • Runny or stuffy nose
  • Sore throat
  • Muscle aches
  • Vomiting and/or diarrhea (more common in children than in adults)

There are several things people can do in order to avoid getting the flu.

Get a Flu Shot

The best way to avoid getting the flu is to get a flu shot (vaccination) every year. Getting a flu shot does not cause the flu. The flu vaccination causes the body to make antibodies against flu viruses. This helps the body to fight off the flu virus after being exposed to it from another person who is sick.

There are several different types (strains) of the flu. Every year the flu shot changes in order to include the strains most likely to be going around that year. This is why it is important to get the vaccination every year.

People with IBD should get the flu shot, which contains inactivated flu viruses. They should not receive the nasal spray flu vaccine, which is alive, attenuated (weakened) flu virus. People with IBD should get the flu shot as soon as it becomes available each year, whether or not they are receiving drugs that suppress the immune system.

Frequent Hand Washing

One of the best ways to avoid getting sick with the flu or other types of infectious diseases is to wash hands thoroughly with soap and water. Keeping hands clean is important to stop the spread of many different types of germs.

Hands should be washed after using the bathroom, after coughing or sneezing, after being around someone who is or who might be sick, and after touching things that have been touched by other people, such as doorknobs, tables, or shopping carts. When soap and water aren't available, use hand sanitizer with a 60% alcohol content.

Avoiding People Who Are Sick

Staying away from people who are sick with symptoms of the flu can also help in avoiding the virus. However, not everyone is able to stay home and avoid other people when they are sick, especially if symptoms are mild. This is why it's important to discuss the risk of the flu at work and at home

Educating Close Contacts

People can have the flu and spread it for between one and four days before their symptoms start. This is why it is important to let those who are close contacts know that people with IBD are at increased risk of complications from the flu.

In this way, if someone thinks they may be sick or if someone close to them is sick, they know to avoid a person who lives with IBD.

If You Get the Flu

Even after taking precautions, the flu still circulates every year and people get sick. People with IBD may want to see a doctor after symptoms of the flu begin. In some cases, medicines called antivirals might be prescribed by a doctor. These drugs might help shorten the duration of the flu and prevent complications, such as pneumonia.

For people who have IBD or other chronic conditions, a doctor may prescribe antivirals even before a person is diagnosed with the flu, if they have been in close contact with someone who is sick.

A doctor can also give more recommendations on treating the flu at home, such as resting, taking in the right amount of fluids, and getting proper nutrition. It's also important to take precautions, such as hand washing, staying home from work or school, and covering coughs and sneezes, to avoid giving the flu to anyone else.

People with IBD should also be vaccinated against pneumonia by getting a pneumococcal vaccine. While getting a shot to prevent pneumonia won't help with avoiding the seasonal flu, it is an important part of IBD care. This is because having IBD already puts people at risk for pneumonia.

Having the flu also increases the risk of later developing pneumonia and also being hospitalized. Getting vaccinated against pneumonia will help in avoiding that complication for anyone who does get the flu. 

When to Seek Care Right Away

Because of the higher risk of not only contracting the flu, but in having complications, people with IBD will want to see a doctor if any severe symptoms start.

For mild symptoms, the flu can usually be managed at home. However, people who are already prone to complications that go along with IBD such as dehydration will want to seek care right away before anything becomes severe.

Signs and symptoms of the flu that should prompt a call to a physician or even a visit to a prompt care center or emergency department include:

  • Dizziness or confusion
  • Fever or cough that improves but then returns or worsens
  • Lack of urination (dehydration)
  • Pain and/or pressure in the chest or abdomen
  • Seizures
  • Severe muscle pain
  • Severe weakness or unsteadiness
  • Shortness of breath/difficulty breathing
  • Worsening of other conditions (such as IBD)

A Word From Verywell

As a society, we have not taken the flu as seriously as we should. Vaccination levels for the flu are not what they should be in order to prevent outbreaks. Vaccinations for many infectious diseases, including the flu, are also low among people with IBD. Receiving the flu vaccine remains the best way to prevent the flu.

Some healthcare providers who are not IBD specialists may not realize that receiving the vaccine is important for people who live with IBD. The vaccine will not cause the flu.

The vaccine should be given even to those who are receiving immunosuppressants. The flu vaccine is safe for people with IBD who are taking medications that dampen the immune system. Having those flu antibodies which confer protection is the most impactful way to avoid coming down with the flu.

Many healthy people may ride out the flu at home without seeing a doctor. People with IBD should seek care right away after being exposed to the flu or when coming down with flu-like symptoms. The potential for complications can be dealt with sooner and a physician can help if there are any steps that need to be taken or symptoms to watch out for.

10 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  4. Centers for Disease Control and Prevention. Flu symptoms & complications. August 31, 2020.

  5. Centers for Disease Control and Prevention. Healthy habits to help prevent flu. September 23, 2020.

  6. Sánchez-Tembleque MD, Corella C, Pérez-Calle JL. Vaccines and recommendations for their use in inflammatory bowel disease. World J Gastroenterol. 2013;19:1354-1358. doi:10.3748/wjg.v19.i9.1354.

  7. Centers for Disease Control and Prevention. When and how to wash your hands. September 1, 2020.

  8. Centers for Disease Control and Prevention. What you should know about flu antiviral drugs. September 3, 2020.

  9. Raghu Subramanian C, Triadafilopoulos G. Care of inflammatory bowel disease patients in remission. Gastroenterol Rep (Oxf). 2016;4:261-271. doi:10.1093/gastro/gow032.

  10. Farraye FA, Melmed GY, Lichtenstein GR, Kane SV. ACG Clinical Guideline: Preventive Care in Inflammatory Bowel Disease. Am J Gastroenterol. 2017;112:241-258. doi:10.1038/ajg.2016.537. 

By Amber J. Tresca
Amber J. Tresca is a freelance writer and speaker who covers digestive conditions, including IBD. She was diagnosed with ulcerative colitis at age 16.