Leer en español  Stay vigilant and take steps to help curb fatal and nonfatal drug overdoses.     Fentanyl Remains Top Cause of Overdoses Fentanyl is the primary opioid responsible for fatal and nonfatal overdoses in the Fairfax Health District. Since 2022, more than 95% of all opioid overdose deaths have involved fentanyl. Information on local overdose trends is available in the Fairfax Opioid Overdose Dashboard.  Fentanyl is an opioid that is a common substitute or cutting agent in…