A study published this week in the Canadian Medical Association Journal says one in every five sexual assaults in Ontario involves allegations of intentionally drugging.

The study — conducted by researchers from the Women's College Research Institute in Toronto and the Ontario Network of Sexual Assault/Domestic Violence Treatment Centres — looked at data collected from a sample of 882 victims.

It found that more than 20 per cent of sexual assaults in the sample size were what the researchers called "drug-facilitated sexual assault," which means the victims were drugged before they were assaulted. In each instance, the victim could not remember the details of the assault.

The victims had reported to seven hospital-based sexual assault and domestic violence treatment centres that serve rural and urban populations in Ontario.

According to the data supplied by the victims to the centres, 30 per cent had taken prescription drugs, 26 per cent had taken over-the-counter medications, and 27 per cent had taken street drugs in the 72 hours before the assault.

Nearly 90 per cent had consumed alcohol immediately before the incident. Some may have consumed alcohol as well as taken prescription drugs.

The study says substances such as prescription, street or over-the-counter drugs have the ability to "alter states of consciousness" and "lower inhibitions," especially when used with alcohol, and can be used to "spike drinks."

It suggests that the victims may also have ingested what are commonly known as date-rape drugs, and the study says the combination of drugs and alcohol could also incapacitate the victims.

The authors say given the results of the study, public education campaigns are needed to combat drug-facilitated sexual assaults. The authors also call for access in hospitals to toxicological screening to detect date-rape drugs to help meet the needs of victims.

"Given that suspected drug-facilitated sexual assault is associated with victims' voluntary substance use, it is imperative that we increase awareness of the effects of using alcohol, particularly in combination with prescription, over-the-counter and street drugs, through public awareness campaigns, including posting information at clubs, pubs, bars, university and college campuses, and community health centres," the study says.

The study says there is also a need to educate men to let them know if a woman is intoxicated, she is incapable of consenting to sexual contact, and that using alcohol and drugs or both to incapacitate a woman in order to have sex with her is the same as committing sexual assault.

The victims in the sample size were both women and men, but the vast majority were women. Of the age groups represented, the largest was between 20 and 24, followed by 16 to 19 years.

Sheila Macdonald, one of the co-authors of the study and a nurse at the sexual assault clinic at Women's College Hospital in Toronto, said victims of drug-facilitated sexual assault often cannot remember key details of what happened, unlike victims of sexual assault who were not drugged.

"So she'll say I woke up someplace, I don't know where I was, or this guy was there, I don't know who he is, I don't remember coming home with him, or there's something different with her clothes or she feels that something happened," Macdonald said.

And if a victim of a drug-facilitated sexual assault does not remember what happened, she said the ordeal is worse and it complicates how medical care staff care for victims.

"I don't want her to come back and be pregnant just because she couldn't remember that she had been actually penetrated," she said.