Anne Heche Under Influence of Cocaine At Time of Car Crash

Anne Heche was not under the influence of alcohol when she crashed her car into a home last Friday, but she was under the influence of cocaine ... this according to law enforcement sources, and possibly fentanyl as well.

LAPD sources tell TMZ ... the department has tested the blood they drew after Anne was admitted to the hospital, and in addition to cocaine, they also found fentanyl. However, our sources say fentanyl is sometimes used as a pain med in hospitals, so they need to do more testing and investigation to determine if the fentanyl was in her system at the time of the crash.

We are also told Anne's condition is dire ... it has not improved since she was admitted to the hospital. As we reported, Anne has been fighting for her life and is in critical condition.

As we reported, Anne was driving her Mini Cooper at an extremely high rate of speed last Friday in a residential area of L.A. when she crashed into a car, a garage and then a house, igniting a fire that severely burned her.