When your immune system turns against your own blood vessels, it’s not just a glitch-it’s a medical emergency. Vasculitis is when your body’s defense system mistakes the walls of your arteries, veins, and capillaries for invaders and starts attacking them. This inflammation can narrow, weaken, or even block blood flow to vital organs. Left untreated, it can lead to organ failure, stroke, or death. But here’s the truth: if caught early, most forms of vasculitis can be controlled. You don’t need to live in fear-just in awareness.

What Happens Inside Your Blood Vessels?

Your blood vessels aren’t just passive tubes. They’re dynamic structures that respond to signals from your immune system. In vasculitis, that signal goes wrong. White blood cells swarm the vessel walls, triggering inflammation. Early on, it’s mostly neutrophils-cells designed to fight infection-climbing into the vessel wall. Over time, lymphocytes take over, and the damage deepens. The inner lining thickens. The middle layer, where elasticity lives, gets shredded. That’s when aneurysms form-bulges in weakened walls that can burst. Or the vessel closes off entirely, starving tissue of oxygen. This isn’t just pain-it’s tissue death waiting to happen.

How Vasculitis Is Classified by Blood Vessel Size

Doctors don’t treat all vasculitis the same. The key is figuring out which vessels are under attack. The classification is simple: large, medium, or small.

• Large-vessel vasculitis targets the aorta and its biggest branches. Giant cell arteritis (GCA) is the most common. It hits people over 50, especially in the temples. If you’re over 50 and get a new, severe headache, jaw pain when chewing, or sudden vision loss-don’t wait. GCA can cause permanent blindness in days.
• Medium-vessel vasculitis affects arteries like the renal or hepatic arteries. Polyarteritis nodosa (PAN) falls here. It often shows up with abdominal pain, nerve damage, or skin ulcers. Kawasaki disease, mostly seen in kids under 5, is another medium-vessel type. It can cause coronary artery aneurysms in 20-25% of untreated cases.
• Small-vessel vasculitis is the most dangerous because it hits the tiny vessels feeding your kidneys, lungs, and nerves. This group includes granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA). These are often tied to ANCA antibodies-autoantibodies that attack white blood cells and trigger vessel damage.

There’s no one-size-fits-all. A rash on your legs might be harmless in one person, but a sign of kidney failure in another. That’s why diagnosis isn’t about one test-it’s about piecing together symptoms, labs, imaging, and sometimes a biopsy.

Key Symptoms You Can’t Ignore

Vasculitis doesn’t announce itself with a loud alarm. It whispers at first. Fatigue. Low-grade fever. Weight loss. These are the red flags that get missed because they look like the flu, stress, or aging.

• Skin: Purple or red spots, bumps, clusters of dots, or bruise-like patches that don’t fade under pressure. These aren’t just allergies-they’re bleeding under the skin from damaged capillaries.
• Lungs: Coughing up blood, shortness of breath, or new chest pain. In GPA and MPA, this is often the first sign of lung involvement.
• Kidneys: You might not feel anything. But blood or protein in your urine? That’s a red flag. The kidneys are silent victims-they show damage long before you feel pain.
• Nerves: Numbness, tingling, or weakness in hands or feet. This isn’t carpal tunnel. It’s nerve damage from inflamed small vessels cutting off blood supply.
• Joints and muscles: Pain and stiffness that moves around, not tied to injury. It’s not arthritis-it’s vasculitis mimicking it.
• GI tract: Abdominal pain after eating, nausea, or bloody stools. This can mean bowel ischemia-a life-threatening blockage.

One study found patients wait 6 to 12 months before getting a correct diagnosis. Why? Because symptoms look like common problems. But if you have more than one of these-especially with unexplained fatigue or fever-see a rheumatologist. Don’t wait for the worst to happen.

How Doctors Diagnose Vasculitis

There’s no single blood test for vasculitis. Diagnosis is a puzzle. Here’s how it’s solved:

• Blood tests: ESR and CRP measure inflammation. If they’re sky-high-over 50 mm/hr and 5 mg/dL respectively-it’s a red flag. ANCA testing is critical. c-ANCA (anti-PR3) points to GPA. p-ANCA (anti-MPO) often means MPA. But here’s the catch: ANCA can be negative in up to 20% of cases. A negative test doesn’t rule it out.
• Urine tests: Even if you feel fine, check for blood or protein. Kidney damage is silent until it’s advanced.
• Imaging: CT or MRI scans show swollen or narrowed vessels. In giant cell arteritis, ultrasound of the temporal artery can reveal a “halo sign”-a thickened wall from inflammation.
• Tissue biopsy: The gold standard. A small sample from affected skin, nerve, kidney, or artery shows the inflammation under the microscope. In cutaneous vasculitis, you’ll see leukocytoclastic debris-nuclear fragments from dead white blood cells-clumped around the vessel walls.
• The Five Factor Score: Used for polyarteritis nodosa, this tool predicts survival. It checks for heart, kidney, GI, or nerve involvement. No major factors? 95% 5-year survival. Two or more? Survival drops to 50%.

Doctors don’t just look for one thing. They look for patterns. A 60-year-old with new headaches and elevated ESR? Think GCA. A 40-year-old with lung nodules, kidney failure, and p-ANCA? Think MPA. The right diagnosis changes everything.

Treatment: From Steroids to Targeted Drugs

Treatment isn’t about curing vasculitis-it’s about stopping the attack and preventing relapse. The goal is remission, not just symptom control.

• High-dose steroids: Prednisone is the first line. Doses start at 0.5-1 mg per kg of body weight. It works fast-often reducing symptoms in days. But long-term use causes bone loss, diabetes, weight gain, and infections. That’s why we don’t keep it on forever.
• Immunosuppressants: Cyclophosphamide was the standard for decades. Now, rituximab (a B-cell killer) is often preferred. It’s just as effective with fewer long-term side effects. For maintenance, methotrexate or azathioprine are used for 18-24 months.
• New drugs: Avacopan, approved in 2021, is a game-changer. It blocks a specific part of the immune system (C5a receptor) and reduces steroid use by about 2,000 mg over a year. Patients get the same results with far less steroid damage.
• For giant cell arteritis: Tocilizumab, an IL-6 inhibitor, is now approved as an add-on. It lets patients taper steroids faster and reduces relapse risk.
• For EGPA: Mepolizumab, originally for asthma, is showing promise in trials-cutting relapse rates by half.

And then there’s Buerger’s disease-vasculitis tied to smoking. No drug works if you keep smoking. Quitting is the only treatment. Period.

Prognosis: Can You Live With It?

The good news? Most people with ANCA-associated vasculitis go into remission. 80-90% do. The bad news? Half of them relapse within five years. This isn’t a one-time fix. It’s a lifelong watch.

Survival depends on how much damage was done before treatment. If your kidneys or lungs were already failing, recovery is harder. But if caught early-before organ damage-your chances are excellent. A 2023 study showed that patients diagnosed and treated within 4 weeks had 3x lower risk of permanent kidney damage than those who waited 6 months.

Children with Kawasaki disease have a different outlook. With timely IVIG and aspirin, most recover fully. But without treatment, 20-25% develop coronary aneurysms. That’s why pediatricians now screen every child with prolonged fever for signs of vasculitis.

What You Can Do Now

If you suspect vasculitis:

1. Write down every symptom-even the small ones. Fatigue, a rash, numbness, a new headache.
2. Don’t wait for a GP to “rule out the common stuff.” Ask for a referral to a rheumatologist.
3. Get a urine test and blood work for ESR, CRP, and ANCA-even if you feel fine.
4. If you smoke, stop now. It’s not just about lungs-it’s about your blood vessels.
5. Keep a symptom journal. Relapses often start with subtle changes.

Vasculitis isn’t a death sentence. It’s a signal. A sign that something inside your body is out of balance. With the right care, you can live a full life. But you have to act before the damage becomes permanent.

Next Steps: What to Do If You Suspect Vasculitis

If you’ve been told your symptoms are “just stress” or “aging,” but they keep getting worse-push back. Write down your symptoms. Bring them to a rheumatologist. Ask for ANCA, ESR, CRP, and a urine test. If your doctor says no, get a second opinion. Vasculitis doesn’t wait. Early treatment saves kidneys, lungs, eyes, and lives.