Lambton OPP seized drugs and a long gun during a traffic stop in Corunna Monday morning.
Police stopped a vehicle on Hill Street just before 6 a.m.
Officers allegedly found a syringe containing suspected fentanyl at the driver's feet.
Police said a further search located a small amount of suspected methamphetamine and a .17 calibre long gun with several rounds of ammunition.
A 50-year-old woman from Walpole Island First Nation faces charges including two counts of possession of a schedule one substance, unauthorized possession and careless storage of a firearm, and driving while under suspension.
The suspect was released pending a future court date.