Infection Risks With IBD Therapies

Infection risks matter whenever inflammatory bowel disease (IBD) is treated with medicines that weaken the immune system. Some infections become more common, and a few “opportunistic” infections can be serious. With good planning, screening, and vaccination before treatment starts, much of this risk can be reduced while still treating Crohn’s disease or ulcerative colitis effectively.

Key Takeaways

• IBD medicines that suppress the immune system raise infection risk, especially systemic steroids, anti‑TNF drugs, thiopurines, and combination therapy. (pmc.ncbi.nlm.nih.gov)

• The biggest additional risks are serious lung infections, shingles, tuberculosis, and reactivation of hepatitis B in carriers. (academic.oup.com)

• Before starting most biologics, thiopurines, JAK inhibitors, or S1P modulators, standard screening usually includes tests for tuberculosis and hepatitis B, plus other viral infections. (academic.oup.com)

• Checking vaccine history early (ideally at diagnosis) makes it easier to give needed non‑live vaccines and any live vaccines before strong immunosuppression begins. (academic.oup.com)

• Long courses of high‑dose steroids and using several immunosuppressive drugs together are major drivers of infection risk that care teams try to limit. (academic.oup.com)

Why infection risk is higher in IBD

People with IBD have a slightly higher risk of some infections even before treatment begins. Active inflammation, poor nutrition, anemia, and frequent hospital visits all play a role. (academic.oup.com)

When immunosuppressive therapy is added, the body’s ability to fight germs is lowered. This makes everyday infections like colds, sinus infections, and pneumonia more frequent, and also increases the chance of “opportunistic” infections that usually affect only people with weakened immunity, such as tuberculosis (TB), shingles, and certain fungal or viral infections. (academic.oup.com)

Risk is not the same for everyone. Older age, other medical problems, malnutrition, and use of more than one immunosuppressive drug at the same time all increase the chance of serious infections. (academic.oup.com)

How different IBD medicines affect infection risk

Not all IBD drugs weaken the immune system to the same degree.

Even though these risks exist, untreated moderate or severe IBD can lead to hospitalizations, surgery, and infection risk from malnutrition and steroids. For many patients, effective immunosuppressive therapy actually lowers overall health risk.

Screening checklist before starting immunosuppressive or biologic therapy

Specialists usually follow a structured checklist before starting thiopurines, methotrexate, biologics, JAK inhibitors, or S1P modulators.

History and risk factors

Typical questions include:

• Past infections such as TB, hepatitis B or C, shingles, recurrent pneumonia, or serious fungal infections. (academic.oup.com)

• Childhood history of chickenpox, measles, and other vaccine‑preventable infections.

• Recent travel or birth in regions with higher TB or fungal infections, such as parts of Asia, Africa, Latin America, or the Ohio and Mississippi River valleys. (academic.oup.com)

• Work exposures (healthcare, shelters, prisons), contact with people who had TB, and household members’ vaccination status. (academic.oup.com)

A review of current medications, alcohol use, and other conditions such as diabetes or lung disease helps estimate overall infection risk. (academic.oup.com)

Lab and imaging tests commonly used

Exact panels vary by country and by drug, but many IBD centers use the following baseline tests:

• Tuberculosis testing

• TB skin test or blood‑based interferon‑gamma release assay (IGRA), plus a chest X‑ray to rule out active disease. (academic.oup.com)

• Recommended before anti‑TNF agents, JAK inhibitors, and usually before any long‑term immunosuppression. (academic.oup.com)

• Hepatitis B and C

• Hepatitis B surface antigen (HBsAg), surface antibody (anti‑HBs), and core antibody (anti‑HBc) to detect carriers and check immunity. (journals.lww.com)

• Hepatitis C antibody testing at baseline.

• Non‑immune patients are usually offered hepatitis B vaccination before biologics when possible. (journals.lww.com)

• HIV and other viral serologies

• HIV testing is commonly performed before or early in immunosuppressive therapy.

• Many guidelines advise checking antibodies for hepatitis A, varicella zoster virus (VZV), measles, Epstein–Barr virus (EBV), and cytomegalovirus (CMV) when vaccination or infection history is unclear. (academic.oup.com)

• General bloodwork

• Complete blood count and liver tests, since low white blood cells or abnormal liver tests can both increase infection risk and affect medication choice. (pmc.ncbi.nlm.nih.gov)

• Cervical cancer and HPV screening

• People with a cervix on long‑term immunosuppressants are advised to keep Pap smears and HPV testing up to date, because HPV‑related changes are more common with some therapies. (academic.oup.com)

Together, this information helps the care team choose the safest therapy, decide on antiviral or TB preventive treatment when needed, and schedule vaccines at the right time.

Monitoring for infections during treatment

Once treatment begins, the focus shifts to early detection and prompt management.

Care teams typically:

• Recheck blood counts and liver tests at regular intervals. (pmc.ncbi.nlm.nih.gov)

• Ask about fever, night sweats, cough, new shortness of breath, painful rashes, shingles‑like blisters, severe sore throat, or new severe diarrhea.

• Encourage rapid medical review if high fever, breathing trouble, confusion, or heavy bleeding develops, since serious infections can progress quickly on immunosuppressive therapy. (academic.oup.com)

Medicines may be paused or adjusted during significant infections, but this is decided case by case by the treating team.

Vaccines as part of prevention

Vaccination is one of the most effective tools to lower infection risk in people with IBD on immunosuppression.

Key principles:

• Non‑live vaccines such as influenza, COVID‑19, pneumococcal, hepatitis A and B, HPV, and recombinant shingles vaccine are recommended for most immunocompromised adults and can usually be given during therapy. (academic.oup.com)

• Live vaccines (for example, measles‑mumps‑rubella or the older live shingles and varicella vaccines) are generally avoided once strong immunosuppression has started and are best given at least 4 weeks before therapy when possible. (academic.oup.com)

A separate article in this series reviews the detailed adult vaccination schedule for people with IBD.

FAQs

Are infection risks a reason to avoid immunosuppressive treatment altogether?

In many cases, untreated moderate or severe IBD causes more long‑term harm than the added infection risk from well‑chosen therapy. Active disease can lead to frequent steroids, hospital stays, and surgery, which also carry infection risk. The safest plan balances disease control with careful screening, vaccination, and monitoring.

Do all patients starting biologics need TB treatment?

No. Everyone should be screened for TB with tests and chest imaging. Only those with evidence of latent or active TB need treatment, and the timing of biologic therapy is adjusted around that treatment. (academic.oup.com)

Should IBD medicines always be stopped when an infection occurs?

For mild infections such as a simple cold, medicines are often continued. For more serious infections, hospitalization, or high fevers, the care team may temporarily pause some drugs until the infection is controlled. Decisions depend on the drug, the infection, and how active the IBD is.