A Study of LY2951742 (Galcanezumab) in Participants With Cluster Headache

Inclusion Criteria: * Participants who participated in and completed either study CGAL or study CGAM. * Investigator judges the participant as reliable to follow all study procedures, keep all study visits, and be compliant with study requirements. Exclusion Criteria: * Current enrollment in or discontinuation within the last 30 days from, a clinical trial involving any investigational drug or device (with the exception of Study CGAL or Study CGAM). * Current use or any prior exposure to any calcitonin-gene-related peptide (CGRP) antibody, any antibody to the CGRP receptor, or antibody to nerve growth factor (NGF) (with the exception of Study CGAL or Study CGAM). * A history of migraine variants that could implicate or could be confused with ischemia. * Known hypersensitivity to multiple drugs, monoclonal antibodies or other therapeutic proteins. * A history or presence of other medical illness that indicates a medical problem that would preclude study participation. * Evidence of significant active or unstable psychiatric disease, in the opinion of the investigator. * Women who are pregnant or nursing.