TL;DR: Giant cell arteritis (GCA) is an inflammation of medium-to-large arteries, often the temple arteries near your eyes. It can suddenly reduce blood flow to the optic nerve and cause permanent vision loss. New headache, scalp tenderness, jaw pain when chewing, or any vision change with shoulder/hip stiffness should be treated as same-day urgent. Doctors often start treatment before all tests are back to protect sight.
What exactly is GCA?
GCA (sometimes called “temporal arteritis”) is an autoimmune inflammation that narrows arteries, most often in the head and neck, and sometimes the aorta and its branches. It usually affects adults over 50 and can travel with polymyalgia rheumatica (PMR). The danger is that swollen artery walls can choke off blood to the eye or brain.
Why it’s an emergency
The eye and optic nerve are very sensitive to drops in blood flow. Without quick treatment, GCA can cause sudden, permanent vision loss—sometimes in one eye first, then the other. Because minutes matter, clinicians often begin high-dose steroids right away if they strongly suspect GCA, and then confirm with testing.
Who is at risk?
- Age ≥ 50 (risk rises in the 60s–70s)
- Women more than men
- People with PMR symptoms (shoulder/hip pain and morning stiffness)
These features don’t prove GCA, but they raise the index of suspicion.
Red-flag symptoms (seek care today)
- New or different headache, especially at the temples
- Scalp tenderness (hurts to brush hair or touch the scalp)
- Jaw pain while chewing that eases when you stop (jaw claudication)
- Vision changes: blurred or double vision; brief blackout or “curtain/shade” over one eye; new vision loss
- Unexplained fever, weight loss, or arm/leg pain with use (large-vessel involvement)
If you have PMR-like symptoms and any of the above, go to urgent care or the ER.
How doctors diagnose GCA
There’s no single test that rules GCA in or out. Doctors combine symptoms, exam, labs, and imaging:
- Inflammation blood tests: ESR and CRP are usually high. (Normal results don’t fully exclude GCA if the story is strong.)
- Ultrasound of the temporal arteries: can show a classic “halo sign” (a dark ring of swelling around the artery). Many guidelines now support early ultrasound to speed diagnosis when expertise is available.
- Temporal-artery biopsy: a small sample checked under the microscope; still useful, especially when imaging is unclear. (Treatment should not be delayed while arranging this if vision is at risk.)
- Imaging for large vessels: ultrasound beyond the head, PET-CT, CTA, or MRA may be used to look at the aorta and its branches.
Treatment
- Start steroids immediately. Most people begin high-dose prednisone (often 40–60 mg/day). If there’s vision loss or threat to vision, many centers give IV methylprednisolone for 3 days before switching to pills. The dose is tapered slowly over months.
- Add-on therapy to reduce steroid exposure: Tocilizumab (Actemra®), an IL-6 receptor blocker, is FDA-approved for GCA and can lower relapse risk and steroid needs in many patients. Your doctor will decide if it fits your case.
Key point: If GCA is strongly suspected, your doctor will typically not wait for test results and start treatment right away. Protecting vision comes first.
Follow-up and long-term safety
- Taper plan & monitoring: frequent visits at first; watch symptoms plus ESR/CRP.
- Large-vessel check: some patients develop inflammation of the aorta; your team may order periodic imaging.
- Bone, blood sugar, blood pressure, eye health: steroids can affect all of these; you’ll likely get a bone-protection plan and risk-reduction tips. (Vaccines and infection prevention are important, too.)
What you can do today
- Don’t ignore new headache, scalp tenderness, jaw pain with chewing, or any vision change.
- If you already have PMR and notice these red flags, contact your clinician the same day or go to urgent care/ER.
- Bring a medication list and a short symptom timeline to help the team move quickly.
