Is It a GPA Flare or Just a Cold? How to Tell

Because Granulomatosis with polyangiitis (GPA) targets the respiratory tract, a disease flare can feel exactly like a stubborn cold or sinus infection. Differentiating between the two at home is notoriously difficult because both can cause sinus congestion, a persistent cough, fever, and deep fatigue ^[1]. However, while a typical viral cold usually peaks in a few days and clears up within a week or two, a GPA flare will persist and often brings back specific, familiar disease symptoms. If you are taking immunosuppressive medications, your body’s ability to fight infections is altered. Therefore, you should never try to guess which one you are experiencing—contact your rheumatologist or ENT for guidance and an expert evaluation.

Clues It Might Be a Flare

While both situations make you feel awful, a GPA flare often carries specific “red flags” that point to active inflammation rather than a passing virus.

Why You Shouldn’t Guess

If you are on immunosuppressants to manage GPA, your body’s ability to fight off a simple respiratory infection is lowered, meaning even a “regular” infection needs careful monitoring and sometimes medical intervention ^[7]. On the flip side, an untreated GPA flare can progress and cause permanent tissue damage ^[2]. Over a long period of chronic, untreated inflammation, this can lead to complications such as a saddle nose deformity (gradual collapse of the nasal bridge) or kidney damage ^[8]. This damage does not happen overnight from a single day of congestion, but it is why catching flares early is critical.

Because the stakes are high, relying on how you “feel” is risky. Both infections and GPA can cause changes in your lungs, such as nodules or infiltrates, which can mimic each other on an X-ray ^[9][7].

When to Contact Your Doctor

You do not need to rush to the emergency room for every mild sniffle, but you should have a low threshold for contacting your care team. A good rule of thumb is to message or call your specialist promptly if:

• You develop any “red flag” symptoms (bloody crusts, joint pain, foamy urine).
• Your symptoms are not improving after a few days, or are rapidly getting worse.
• You have a high fever.

Never stop or adjust your immunosuppressant medications without talking to your doctor first. Always ask your care team whether you should pause your doses while you are feeling sick.

What Your Doctor Will Check

To tell the difference, your care team will rely on specific laboratory markers and clinical assessments:

• Inflammatory Markers (CRP and ESR): Tests like C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) measure general inflammation in the body. While they can spike during both an infection and a flare, tracking them alongside your symptoms helps your doctor see the bigger picture ^[10].
• Procalcitonin: This is a specific blood marker that typically rises during a bacterial infection but often stays normal or lower during an autoimmune flare ^[11].
• ANCA Levels: Your doctor may check your ANCA (anti-neutrophil cytoplasmic antibody) blood levels. While a rising ANCA level can sometimes signal an upcoming relapse, it isn’t a perfect tool—some patients experience flares even with negative ANCA tests ^[12][13].
• The BVAS Score: Your doctor may use the Birmingham Vasculitis Activity Score (BVAS), a specialized checklist of symptoms and lab results used to calculate exactly how active your GPA is ^[14].