Is one hydrocodone really bad with alcohol?

It can be: Depending on how much hydrocodone and how much alcohol. Sedating drugs together than have either an additive effect (1+1=2) or a synergistic effect (1+1=5) where the level of sedation in taking even modest doses of the two drugs can cause respiratory depression, coma and death. One hydrocodone together with 1-2 social drinks is unlikely to cause major harm, but with large amounts of alcohol it can.