As a result of working as her husband's assistant, she acquired knowledge of health and nutrition which enabled her in 1871 to publish Veiledning i Tilberedelse af Mad for Syge og Svage (Guide to the Preparation of Food for the Sick and Weak). After her husband's death in 1928, she moved to Copenhagen where she supplemented her income by writing. She began with accounts of life in Jutland which included En gammel Mands Erindringer (An Old Man's Memoirs, 1875), Hedens Hemmeligheder (Pagan Secrets, 1877), and Sorte Stefan (Black Stefan, 1879). Her most significant novels and short stories were however those about women in romantic situations which emphasized their emancipation and their place in their home. These included En Magdalenehistorie (A Magdalene Story, 1877) about a fallen girl rescued by a bourgeois housewife, Askepot (Cinderella, 1880, To Fortællinger (Two Stories, 1886) and Præst og Læge (Priest and Doctor, 1890). Her works were well received but some were felt to be rather sketchy. Some were translated in German, English and Russian.[1][4]
Fibiger was a keen contributor to magazines, writing about the women's cause and the important role women should play in the home. In 1882, she established Tidsskrift for Kvinder i de tre nordiske Riger (Journal for Women in the Three Nordic Realms) which closed in 1884. She also supported the efforts of the Danish Women's Society, explaining how women could become active in philanthropy and pedagogy. In particular, she emphasized the role of women in the kitchen, explaining the importance of hygiene and nutrition. Publications included Vore Tjenestefolk (Our Servants, 1881), Den ubemidlede Klasses Døtre (Daughters of the Wealthy, 1888), and Nutidens Ansvar og Forpligtelser overfor Døttrene af Arbeiderklassen og anden ubemidlet Stand (Our Current Responsibilities and Obligations towards Working-Class Women, 1889). She supported educational institutions designed to counter prostitution by taking a moral stand.[1]
Elfride Fibiger died in Copenhagen on 2 January 1911 and was buried in Kolding.[2] Her memoirs describing her married life, Fra Provinsen (From the Provinces), were published posthumously in 1939.[1]