[5] In the revised classification to create monophyletic genera, the cinnamon-sided hummingbird was one of three species moved to the resurrected genus Leucolia by some taxonomic systems.

[7][8][3] As of that date the Clements taxonomy retains the species in Leucolia and BirdLife International's Handbook of the Birds of the World (HBW) in the earlier Amazilia.

Their underside from throat to undertail coverts is pure white with the eponymous cinnamon sides and flanks.

As is the case with breeding information, the cinnamon-sided hummingbird's vocalizations are not described separately from those of the green-fronted sensu lato.

[10] The IUCN has assessed the cinnamon-sided hummingbird as being of Least Concern, though it has a very limited range and its population size is not known and believed to be decreasing.