I am currently working to significantly reduce my fioricet usage. while this effort is ongoing, what are the likely and potential long-term side effects of using 5 tablets of fioricet daily?

Fioricet is habit forming. Since fioricet contains barbiturates, drowsiness & dizziness are concerns and could impair ones ability to safely drive or operate machinery. Barbiturate overdose can be fatal. The acetaminophen in 5 tabs a day can interact with alcohol causing liver damage. I applaud your intention to wean off fioricet. Caffeine excess raises blood pressure & heart rate.