Abstract Introduction: Medication overuse headache is a condition where abrupt drug withdrawal is considered the treatment of choice. Objective: To study whether prednisolone given orally the first 6 days after medication withdrawal reduces headache intensity during the same period. Methods: From August 2003 through November 2005, we included patients aged 18 to 70 years with probable medication overuse headache. The study was randomized, double-blind, and placebo controlled. The patients were hospitalized for 3 days to start medication withdrawal. They were randomly assigned to receive prednisolone 60 mg on days 1 and 2, 40 mg on days 3 and 4, and 20 mg on days 5 and 6 (Group A) or placebo tablets for 6 days (Group B). Headache intensity was recorded in a diary for a month before withdrawal (baseline) and throughout the study period of 28 days. The primary endpoint was a calculated mean headache (MH), based on number of days with headache and mean intensity the first 6 days after withdrawal. Results: We included 26 men and 74 women. Sixty-five had migraine, 13 had tension-type headache, and 22 had both migraine and tension-type headache. Baseline headache days were 25.4 (CI 24.3 to 26.4). Baseline MH was 1.6 (CI 1.41 to 1.69). Fifty-one received Regimen A, and 49 received Regimen B. Baseline features were similar. During the first 6 days after withdrawal, headache was similar in Groups A and B (MH 1.48 [CI 1.28 to 1.68] vs 1.61 [CI 1.41 to 1.82], p = 0.34). Conclusion: Prednisolone has no effect on withdrawal headache in unselected patients with chronic daily headache and medication overuse.