Prolonged use of the following drug has been implicated in the causation of subacute myelo-optic neuropathy (SMON):

Prolonged/repeated use of relatively high doses of quiniodochlor causes a neuropathic syndrome called "subacute myelo-optic neuropathy" (SMON) 8-hydroxyquinolines like quiniodochlor were widely used treat infection by Entamoeba, Giardia, Trichomonas, some fungi (dermatophytes, Candida) and some bacteria. They kill the cyst forming amoebic trophozoites in the intestine, but do not have tissue amoebicidal action.