Are all side effects heightened? This is in a 45 yr. old male good health, 125 lbs. taking meds properly. He experienced a 12-24 blackout period, he is not taking either med now. It was the first time he had been given Fentanyl (patch), his behavior changed about 18 hrs. after the first patch was applied. He took Halcion before going to bed, and thought he slept, he drove, went to the store etc. remembers none of this. Can you help answer what happened?