Introduction In a multicenter, double-blind, randomized, parallel-group, placebo-controlled, single-dose study ( n = 1555), a fixed combination of acetaminophen 500 mg, acetylsalicylic acid 500 mg, and caffeine 130 mg (AAC) was compared with ibuprofen 400 mg (IB) and placebo (PLA) for acute treatment of migraine. Subjects and methods An exploratory post-hoc analysis compared AAC with IB and PLA in the subset of patients with severe pain at baseline ( n = 660). Results At most time points, AAC and IB relieved the pain and associated symptoms of severe migraine significantly better than PLA ( p ≤ 0.05). AAC was significantly superior to IB for pain relief at 45 minutes and at one, two, three, and four hours postdose ( p < 0.04); pain intensity difference from one hour through three hours ( p < 0.05); headache response at two hours ( p = 0.04); functional disability reduced to little or none at three hours ( p = 0.013); freedom from phonophobia at three hours ( p = 0.04) and photophobia at 15 minutes postdose ( p = 0.03); and use of rescue medication ( p = 0.018). AAC patients also reported meaningful pain relief 16 minutes faster than IB patients (132 minutes vs 148 minutes, p = 0.026). Conclusions In patients with severe baseline migraine pain, AAC and IB are significantly more effective than PLA, and AAC provides significantly faster and more effective pain relief than IB.