Buy Dilaudid 8 mg. Hydromorphone is an opioid pain reliever. An opioid is sometimes called a narcotic. Dilaudid 8 mg is used to treat moderate to severe pain. The extended-release form of this drug is intended for the treatment of moderate to severe pain around the clock. This form of Dilaudid 8 mg is not intended for on-demand use for pain. Dilaudid 8 mg hydromorphone may also be used for purposes not listed in this Medication Guide.