Corticosteroid treatment should start directly after suspected diagnosis. The diagnosis should be confirmed within the next 5 days by histology or ultrasound. Clinical assessment includes auscultation of the axillary arteries in the search for large-vessel giant cell arteritis. Angiography, magnetic resonance angiography, positron emission tomography, or ultrasound can confirm the diagnosis of large-vessel giant cell arteritis. The initial prednisolone dose is 40 to 70 mg/d. It should be reduced in weekly steps of 5 to 10 mg until 20 mg/d, and by 2.5 mg until 10 mg/d. Dose reduction is 1 mg/mo below 10 mg/d, depending on symptoms and erythrocyte sedimentation rate or C-reactive protein. Patients with ophthalmologic complications receive three to four daily infusions of 250 mg of methylprednisolone for 3 days. Low-dose aspirin reduces the risk of ophthalmologic and cardiovascular complications. The benefit of methotrexate as a corticosteroid-sparing agent is controversial. Corticosteroid treatment requires monitoring of glucose, blood and eye pressure, and adequate prevention of osteoporosis.