“Unless you’ve got patient’s hair samples or urine samples or blood samples almost immediately, it’s very difficult to detect that,” Rosenthal said.

Sarah B. Levit-Shore ’04, a member of the Coalition Against Sexual Violence, said that awareness efforts like the warning e-mail are important because people may not think that date rape drugs are a problem at Harvard.

But she said that people must also recognize that taking precautions does not guarantee safety.

“Hopefully, understanding the reality will help people to take steps to reduce their risk,” Levit-Shore said. “But it’s critically important to realize that you can do everything right and still find yourself in a situation that is dangerous...You should look both ways before you cross the street, but you can look both ways and still get hit by a car.”

Rohypnol is a sleeping pill in Europe, produced by Switzerland-based Hoffman-La Roche Pharmaceuticals. The company’s latest pills turn blue in alcohol to avoid abuse, but there are American manufacturers that produce imitation drugs, according to Dr. Christopher M. Coley, a general internist at UHS.

Coley said that drugs such as Rohypnol pose dangers because when combined with even a small quantity of alcohol, they can severely depress the central nervous system, causing asphyxiation.

“They can be quite deadly,” Coley said. “It’s quite clinically potentially dangerous in use with alcohol, but also dangerous if someone is going to be a victim of sexual abuse.”

—Staff writer David B. Rochelson can be reached at rochels@fas.harvard.edu.