The eight men were tried in November on charges of "inciting debauchery" after they appeared in a viral video showing a symbolic same-sex marriage in a boat on the river Nile.
Egypt's forensics authority said the accused men had undergone physical inspections and were found to be "not gay", according to the news outlet.
There is no law explicitly outlawing homosexuality in Egypt, but prosecutors may try homosexuals under laws banning debauchery.
Earlier this year, an Egyptian court sentenced six men to two years in prison for allegedly promoting their homes as a venue for homosexual acts. In another recent case, four men were sentenced to eight years in jail for debauchery after allegedly committing homosexual acts.
The reduced jail sentences come amid criticism that Egypt is leaning towards authoritarianism. The successors of former president Mohamed Morsi, who was overthrown in a 2013 uprising, have in recent months been accused by both local and international rights groups of using the lack of an elected parliament to rule by decree in ways that highly restrict freedom of expression and assembly.