Gula, later a distinct goddess, was possibly initially an epithet of Ninisina, as references to Ninisina-gula ("Ninisina, the great") occur in Neo-Sumerian (Ur III) sources and in a hymn from the reign of Ishbi-Erra. Gula's name could be used as a translation of Ninisina's in Akkadian versions of Sumerian compositions. She is also referred to as "Ninisina of Umma" in documents from Puzrish-Dagan, as the scribes from this location were more familiar with the latter goddess, and used her name to represent other healing deities. It has been argued this is more likely to reflect a convention similar to interpretatio graeca rather than theological syncretism between the two goddesses. Ninisina is entirely absent from known texts from Umma, and had no cult in this city, though in an inscription from the Ur III period the local governor Lu-Utu calls himself a son of this goddess. Barbara Böck argues that Ninisina was fully absorbed by Gula in the centuries following the reign of Ishbi-Erra, but according to Irene Sibbing-Plantholt the association between them is only attested in Isin after Hammurabi's conquest of the city, and Christina Tsouparopoulou states that it is not certain if they were viewed as identical in the Old Babylonian period. Ninisina is not listed among the goddesses conflated with Gula in the Gula Hymn of Bulluṭsa-rabi, which was most likely composed between 1400 BCE and 700 BCE. An inscription which still mentions them as separate goddesses is known from the Neo-Babylonian period. While both Ninisina and Gula could be associated with Damu, the former came to be viewed as his mother earlier than the latter.
