I don’t know about those ingredients, but most cold medicine contains some sort of sedative or depressant, like alcohol. This can cause REM rebound and in some cases very vivid nightmares.
if it has an affect i would guess its the dxm, since that is a hallucinogen in high doses, in small doses it probably has a small psychoactive effect. people have reported similarly with nutmeg. i wouldn’t do it though.