After the suspected rape of a teenage girl at a party over the weekend, police and women's advocates in B.C. are warning teens about the dangers of so-called "date-rape" drugs.

Investigators believe that the 16-year-old victim was drugged -- likely with GHB or Rohypnol -- before the assault at a party in Pitt Meadows, but are still waiting for test results to confirm that suspicion.

Marissa MacDonald, founder of the defunct Student Nurses for Clean Drinks, says that these date-rape drugs can virtually incapacitate women.

"We're talking about something that has the ability to completely knock you out," she told CTV News.

MacDonald began her campaign to educate women about the drugs after a friend's drink was spiked at a bar. Within 15 minutes, the friend became extremely dizzy, nauseous and clumsy, and when she was taken home, her breathing slowed and she began to experience hallucinations and amnesia.

"If someone's ingested the date-rape drugs, which procure a sexual assault, what you see is a woman who is almost asleep, you're not able to scream for help, you're not able to kick or fight somebody off. Somebody who decides to do a rape using these drugs is the epitome of a coward," MacDonald said.

The drugs are hard to detect because they wear off after eight or 10 hours.

"By the time the victim is becoming conscious enough and aware that something's happened to them and they seek medical attention, often the concentration of the drug in the system has dissipated to what might be considered a naturally-occurring level of that substance," RCMP Sgt. Jennifer Hyland said.

Although GHB is known as "the date-rape drug," Daisy Kler of Vancouver Rape Relief and Women's Shelter says that alcohol and prescription drugs are much more commonly used to facilitate sexual assault.

"Women usually don't have a very good memory and are not sure what's happened to them," she said.

"This cannot be understood as anything consensual; this woman was not in a position to give consent."

Police are cautioning women to stay close to friends when they're out and keep an eye on their drinks.

With a report from CTV British Columbia's Leah Hendry