Previous use of botulinum toxin of any serotype or immunization to any botulinum toxin serotype

Any medical condition that puts the patient at increased risk with exposure to BOTOX

Diagnosis of complicated migraine, chronic tension-type headache, hypnic headache, hemicrania continua, new daily persistent headache

Use of prophylactic headache medication within 28 days prior to week -4

Unremitting headache lasting continuously throughout the 4-week baseline period

Known or suspected TMD

Diagnosis of fibromyalgia

Beck depression inventory score \>24 at week-4

Psychiatric problems that may have interfered with study participation

A Study Using Botulinum Toxin Type A as Headache Prophylaxis for Migraine Patients With Frequent Headaches