A 20-year-old Waterloo man has been charged with putting a “noxious substance” in a woman’s drink. He was arrested Friday night at a bar on King Street North.

Police say the woman spotted the substance in her drink and brought it to the attention of bar security. The contents of the drink have been sent a lab for testing.

Police are not naming the establishment.

There are also investigating a similar incident a week ago. They say a woman was drinking at a bar when she suddenly became sick.

“She needed medical attention for this,” said Insp. Kevin Thaler, of the Waterloo Regional Police. “The threat to the public is real. People just need to be aware. If they’re going to leave their drink unattended, leave it with a trusted friend.”

Police say they’ll be sharing that advice with university and college students. They’ll also be going to local bars to remind them about the risks of drink tampering.