Around one million United States emergency department (ED) visits annually are due to acute decompensated heart failure (ADHF) symptoms. Characterizing ED symptom presentation of ADHF patients may improve clinical care, yet sex and age differences in ED chief complaints have not been thoroughly investigated. This paper aims to describe differences in chief complaints and comorbid conditions for ED patients with a ADHF diagnosis, stratified by sex and age. Retrospective analysis of adults presenting to North Carolina EDs in NC DETECT, a statewide syndromic surveillance system, between 2010 and 2016 with a diagnosis of ADHF. Frequencies of chief complaint categories for ED visits and comorbid conditions, stratified by sex and age, were evaluated and standardized differences computed. Top chief complaints were dyspnea (19.1%), chest pain (13.5%), and other respiratory complaints (13.4%). In the 18-44 age group, females when compared to males reported more nausea/vomiting (6.7% versus 4.1%) and headache (4.2% versus 2.0%). In those 45-64 and 65+ years old, complaints were similar by sex. When stratified by age group alone, the 18-44 and 45-64 age groups had more complaints of chest pain, whereas balance issues, weakness, and confusion were more common in the 65+ age group. Sex and age differences in atypical ADHF symptoms were seen in in ED patients with ADHF. Characterizing variation of ADHF symptoms in ED patients can inform the identification of ED patients with ADHF and the management of ADHF-related symptoms.