Meds & Escalation
Catching a cold or flu is annoying for anyone, but when you have Crohn's disease and take immunosuppressive medications, a routine illness can feel far more loaded. Biologics like infliximab and adalimumab, immunomodulators like azathioprine and methotrexate, and corticosteroids all dampen the immune response that keeps Crohn's inflammation in check. That same dampening, however, means your body has fewer defenses against everyday infections. Research published in Inflammatory Bowel Diseases found that IBD patients on immunosuppressive therapy had a higher rate of influenza and were more likely to be hospitalized from it compared to the general population (Kirchgesner et al., 2018). Knowing how to handle a sick day before one arrives can save you a lot of worry and help you make better decisions in the moment.
What to do when you first feel sick
The first 24 to 48 hours of a cold or flu are when your actions matter most. Start by contacting your gastroenterologist's office or IBD nurse line, even if it seems like a minor bug. The Crohn's & Colitis Foundation recommends that immunosuppressed patients who develop signs of infection, including fever, chills, or persistent cough, notify their care team promptly (Crohn's & Colitis Foundation, Influenza Information). Your GI team may want to check bloodwork, especially your white blood cell count, to make sure your immune system is not suppressed beyond safe levels. If you have the flu specifically, antiviral medications like oseltamivir (Tamiflu) are most effective when started within two to three days of symptom onset and can shorten the illness or reduce its severity. Do not wait to see if you "get over it" on your own. Early communication with your care team gives them the best window to intervene if needed.
Should you hold your biologic or immunomodulator?
This is one of the most common questions Crohn's patients ask, and the answer is never a solo decision. The FDA prescribing information for infliximab states that patients should not receive the drug during an active serious infection, and that treatment should be discontinued if a serious infection develops (FDA Infliximab Label). However, not every cold or mild respiratory infection qualifies as "serious." A standard cold without fever may not warrant holding your medication, while a confirmed flu with high fever likely does. Your gastroenterologist will weigh the severity of the infection against the risk of a Crohn's flare from pausing treatment. Factors like how long you have been stable, which medication you take, and how close your next dose is all play into the decision. The key point: call your GI team before skipping a dose on your own. An unplanned gap in biologic therapy can lead to antibody formation against the drug, which may reduce its effectiveness long-term.
How to tell if it is a flare or an infection
When your gut symptoms worsen while you are fighting a cold or flu, it can be hard to tell whether you are dealing with a viral stomach bug, a Crohn's flare triggered by the stress of illness, or both at the same time. There are some patterns that can help you and your doctor sort it out. A stomach virus typically resolves within one to three days. If diarrhea, cramping, or urgency persists beyond that window, a flare becomes more likely. Blood or mucus in your stool is a strong indicator of Crohn's-related inflammation rather than a viral infection. Extraintestinal symptoms like joint pain, skin changes, or eye redness also point toward disease activity rather than a passing bug (Mayo Clinic, Crohn's Disease Symptoms). Fever adds complexity because both infections and active Crohn's can cause it, though a low-grade fever that lingers after other viral symptoms have cleared often signals intestinal inflammation. If you are unsure, your GI team can order a fecal calprotectin test or C-reactive protein level to check for active bowel inflammation and help distinguish the two.
When to go to the emergency room
Most colds and even mild flu can be managed at home with rest, fluids, and communication with your GI team. But certain symptoms in an immunosuppressed person should prompt an ER visit. A fever above 101.3 F (38.5 C) that does not respond to acetaminophen deserves urgent evaluation, as do signs of dehydration you cannot correct by drinking, such as dizziness when standing, dark urine, or a rapid heart rate. Persistent vomiting that prevents you from keeping down medications, including your Crohn's drugs, is another reason to seek emergency care. The Sepsis Alliance notes that immunocompromised patients are at greater risk of infections progressing to sepsis, and that early recognition of warning signs like confusion, rapid breathing, or extreme fatigue can be life-saving (Sepsis Alliance, Infection Prevention in Immunocompromised People). When in doubt, err on the side of being seen. A brief ER visit that turns out to be unnecessary is far better than a delayed one that was not.
Keeping a record for your care team
One of the most practical things you can do during a sick day is document what happened. Write down the dates you felt ill, any fever readings, which medications you took or skipped, and when your symptoms resolved. This information is surprisingly valuable at your next gastroenterology appointment. If your GI asks whether you paused your biologic and for how long, having exact dates matters for interpreting lab results, adjusting your treatment schedule, and deciding whether you need drug-level testing. Log sick days and any medication holds in Aidy. When your GI asks whether you paused your biologic and for how long, you will have the exact dates ready, and that small act of preparation can meaningfully improve the conversation about your care.