Giant cell arteritis (GCA) inflames the lining of your arteries. Most often, it affects arteries in your head, causing symptoms like head and jaw pain. It used to be called temporal arteritis because it can cause inflammation in the arteries in the temples.

Swelling in the blood vessels reduces the amount of blood that can flow through them. All of your tissues and organs rely on oxygen-rich blood to function properly. A lack of oxygen can damage these structures.

Treatment with high doses of corticosteroid medications like prednisone brings down inflammation in the blood vessels quickly. The earlier you start taking this medication, the less likely you’ll develop complications like the following.

Blindness is one of the most serious and worrisome complications of GCA. When there isn’t enough blood flow into the artery that sends blood to the eye, the tissue that the artery feeds starts to die. Eventually, a lack of blood flow to the eyes can cause blindness.

Often, only one eye is affected. Some people lose sight in the second eye at the same time, or a few days later if they don’t get treated.

The vision loss can happen very suddenly. There’s usually no pain or other symptoms to warn you.

Once you lose vision, you can’t get it back. That’s why it’s important to see an eye doctor or rheumatologist and get on treatment, which usually involves taking a steroid medication first. If you have any changes in your vision, alert your doctors right away.

Although GCA is rare overall, it’s one of the main causes of aortic aneurysm. The aorta is your body’s main blood vessel. It runs down the middle of your chest, carrying blood from your heart to the rest of your body.

An aneurysm is a bulge in the wall of the aorta. It happens when your aorta wall is weaker than usual. If an aneurysm bursts, it can cause dangerous internal bleeding and death if emergency treatment is not given.

Aortic aneurysms don’t usually cause symptoms. Once you’ve been diagnosed with GCA, your doctor may monitor you for aneurysms in the aorta and other large blood vessels with imaging tests like ultrasound, MRI, or CT scans.

If you get an aneurysm and it’s large, doctors can repair it with surgery. The most common procedure inserts a man-made graft into the aneurysm site. The graft strengthens the weakened area of the aorta to prevent it from rupturing.

GCA increases your risk of an ischemic stroke, although this complication is rare. An ischemic stroke happens when a clot blocks the flow of blood to the brain. A stroke is life-threatening and needs prompt treatment in a hospital, preferably one with a stroke center.

People who have a stroke are more likely to have GCA symptoms like jaw pain, short-term vision loss, and double vision. If you have symptoms like these, let your doctor know about them right away.

People with GCA are also at a slightly higher risk of a heart attack. It’s not clear whether GCA itself causes heart attacks, or if the two conditions share the same risk factors, particularly the inflammation.

A heart attack happens when an artery that supplies your heart with blood becomes blocked. Without enough blood, sections of the heart muscle begin to die.

Getting quick medical care for a heart attack is important. Watch out for symptoms like:

  • pressure or tightness in your chest
  • pain or pressure that radiates to your jaw, shoulders, or left arm
  • nausea
  • shortness of breath
  • cold sweat
  • dizziness
  • tiredness

If you have these symptoms, call 911 or go to a hospital emergency room right away.

People with GCA are also at a slightly higher risk of peripheral artery disease (PAD). PAD reduces blood flow to the arms and legs, which can cause cramping, numbness, weakness, and cold extremities.

Similar to heart attacks, it’s not clear whether GCA causes PAD, or if the two conditions share common risk factors.

Polymyalgia rheumatica (PMR) causes pain, muscle weakness, and stiffness in the neck, shoulders, hips, and thighs. It isn’t a complication of GCA, but the two diseases often occur together. About half of people with GCA also have PMR.

Corticosteroid drugs are the main treatment for both conditions. In PMR, prednisone and other drugs in this class help to relieve stiffness and bring down inflammation. Lower doses of prednisone can be used in PMR than in GCA.

GCA can cause several complications. One of the most serious and concerning is blindness. Once you lose vision, you can’t get it back.

Heart attack and stroke are rare, but they can happen in a small percentage of people with GCA. Early treatment with corticosteroids can protect your vision, and help prevent other complications of this disease.