What Is the Risk of Developing GCA if You Have PMR?

If you have Polymyalgia Rheumatica (PMR), your risk of eventually developing Giant Cell Arteritis (GCA) is generally between 15% and 20% ^[1][2]. PMR and GCA are not completely separate diseases; they are closely related conditions that exist on the same disease spectrum ^[3][4]. While PMR causes inflammation primarily in the joints and muscles (leading to stiffness), GCA involves inflammation of the blood vessels.

Because of this strong connection, anyone diagnosed with PMR needs to remain vigilant for the signs of GCA. Fortunately, if GCA is caught early, it is highly treatable and irreversible damage can be prevented.

The Steroid Misconception

A common and dangerous misconception is that because you are already taking steroids (such as prednisone) for PMR, you are protected against getting GCA. This is not true.

The standard steroid doses used to treat PMR—typically between 12.5 and 20 mg per day—are not high enough to prevent the blood vessel inflammation of GCA ^[5][6]. GCA usually requires much higher starting doses, often between 40 and 60 mg daily, to stop the inflammation and protect your vision.

Furthermore, the lower doses of steroids used for PMR can sometimes hide or “mask” the early warning signs of GCA ^[5][7]. GCA can develop at any time during your PMR journey, but it is especially important to be on guard when you and your doctor are tapering (gradually lowering) your steroid dose ^[5][7].

Red Flag Symptoms to Watch For

Because GCA can develop suddenly and threatens your vision, you must know the warning signs. If you experience any of the following symptoms, do not wait for your next scheduled appointment.

• Vision Changes (Medical Emergency): Any sudden blurring, double vision, shadows, or temporary loss of vision in one or both eyes requires an immediate trip to the Emergency Room ^[8][9]. Do not wait for a doctor’s callback, as urgent treatment is required to prevent permanent blindness.
• New or Unusual Headaches: This is often the most common symptom. It is usually a new type of headache that you haven’t experienced before, frequently located in the temples, though it can occur anywhere on the head ^[10][11].
• Jaw Claudication (Jaw Pain): This is pain, cramping, or fatigue in your jaw muscles that happens when you are chewing food or talking for a long time ^[12][13]. This happens because the chewing muscles aren’t getting enough blood flow, which helps distinguish it from standard joint pain or TMJ issues.
• Scalp Tenderness: You may notice pain when brushing your hair, washing your scalp, or wearing glasses or a hat ^[10].
• Return of Flu-Like Symptoms: If you experience unexplained fever, extreme fatigue, or a sudden return of severe stiffness while taking steroids, it may be a sign of spreading inflammation ^[6][7]. While normal PMR flares can happen during a steroid taper (usually as returning joint stiffness), a flare accompanied by fever, head pain, or the symptoms above strongly points toward GCA.

“Silent” Inflammation

Recent research has shown that some patients with newly diagnosed PMR actually have “subclinical” GCA—meaning they have blood vessel inflammation that is not yet causing obvious symptoms ^[1][2]. Because of this, your doctor may regularly monitor your blood tests for inflammatory markers, specifically C-Reactive Protein (CRP) and Erythrocyte Sedimentation Rate (ESR), even when you feel well ^[6]. They may also suggest imaging tests like an ultrasound, which typically checks the temporal arteries (at the temples) or axillary arteries (in the armpits), to look at your blood vessels directly ^[7].