Toronto police say a harm reduction worker has been charged after he allegedly assaulted a woman and injected her with an unknown substance over a period of several weeks.

Police say a 65-year-old woman would meet the man at a home, where he would allegedly assault her.

Investigators allege that when the woman went to sleep, the 49-year-old man would inject her with a unknown substance.

Police say the alleged incidents occurred between Oct. 30 and Dec. 6.

Police say the 49-year-old Toronto man works with drug users at the South Riverdale Community Health Centre.

The man is facing numerous charges including administering a noxious substance, forcible confinement, assault with a weapon and two counts of assault.