An Open Label Extension Study of Duloxetine (LY248686) in Participants With Chronic Low Back Pain

Inclusion Criteria: (Consecutive Participants): * Participants who have completed the 15-week administration in the phase 3 clinical study of Duloxetine hydrochloride in participants with CLBP, study HMGY (NCT01855919) * Female participants having child-bearing potential must test negative (-) on a pregnancy test (New Participants): * Participants with CLBP present for the preceding 6 months or longer * Participants used nonsteroidal anti-inflammatory drugs for CLBP for less than 14 days on average per month in the past 3 months and less than 14 days in one month prior to study * Participants having a score of ≥4 on Brief Pain Inventory (BPI) average pain score at participation of study * Female participants having child-bearing potential must test negative (-) on a pregnancy test Exclusion Criteria: (Consecutive Participants): * Participants having serious or unstable cardiovascular, hepatic, renal, metabolic, respiratory, or hematologic illness, symptomatic peripheral vascular disease, or other medical condition or psychiatric conditions that, in the opinion of investigator, would compromise participation or be likely to lead to hospitalization during the course of the study * Participants having alanine aminotransferase or aspartate aminotransferase higher than 100 International Units per Liter (IU/L) or total bilirubin higher than 1.6 milligram per deciliter (mg/dL) * Participants having serum creatinine level higher than 2.0 mg/dL, or had renal transplantation or receiving renal dialysis * Participants having diagnosis seronegative spondyloarthropathy or rheumatoid arthritis * Participants having primary painful condition due to other than CLBP * Participants having uncorrected thyroid disease, uncontrolled narrow-angle glaucoma, history of uncontrolled seizures, or uncontrolled or poorly controlled hypertension * Participants treating with a monoamine oxidase inhibitor (MAOI) within 14 days or the potential need to use an MAOI during the study or within 5 days of discontinuation of study drug * Participants answering "yes" to any of the questions about active suicidal ideation/intent/behaviors occurring within the past month (Columbia Suicide Severity Rating Scale, Suicide Ideation section - Questions 4 and 5; Suicidal Behavior section) * Pregnant participants or participants who are breast-feeding, or wished to be pregnant during the clinical trial period * Participants cannot use appropriate contraceptive method or do not want to use that from participation of study until one month after the end of administration of the investigational drug * Participants being considered as inappropriate for participation to the study for any medical or other reason as judged by the investigator (New Participants): * Participants having serious or unstable cardiovascular, hepatic, renal, metabolic, respiratory, or hematologic illness, symptomatic peripheral vascular disease, or other medical condition or psychiatric conditions that, in the opinion of investigator, would compromise participation or be likely to lead to hospitalization during the course of the study * Participants having alanine aminotransferase or aspartate aminotransferase higher than 100 IU/L or total bilirubin higher than 1.6 mg/dL * Participants having serum creatinine level higher than 2.0 mg/dL, or had renal transplantation or receiving renal dialysis * Participants having diagnosis seronegative spondyloarthropathy or rheumatoid arthritis * Participants having primary painful condition due to other than CLBP * Participants having a history of low back surgery * Participants having any previous diagnosis of psychosis, bipolar disorder, or schizoaffective disorder * Participants having major depressive disorder as determined using depression module of the Mini-International Neuropsychiatric Interview * Participants having uncorrected thyroid disease, uncontrolled narrow-angle glaucoma, history of uncontrolled seizures, or uncontrolled or poorly controlled hypertension * Participants treating with a MAOI within 14 days or the potential need to use an MAOI during the study or within 5 days of discontinuation of study drug * Participants answering "yes" to any of the questions about active suicidal ideation/intent/behaviors occurring within the past month (Columbia Suicide Severity Rating Scale, Suicide Ideation section - Questions 4 and 5; Suicidal Behavior section) * Participants have known hypersensitivity to multiple medications * Participants are non-ambulatory or require the use of crutches or a walker * Participants having a history of substance abuse or dependence within the past year, excluding nicotine and caffeine * Participants having a positive urine drug screen for any substances of abuse * Participants have received treatment within the last 30 days with a drug that has not received regulatory approval for any indication * Participants have had previous exposure to duloxetine or completed / withdrawn from any study investigating duloxetine * Pregnant participants or participants who are breast-feeding, or wished to be pregnant during the clinical trial period * Participants cannot use appropriate contraceptive method or do not want to use that from participation of study until one month after the end of administration of the investigational drug * Participants being considered as inappropriate for participation to the study for any medical or other reason as judged by the investigator