You can do the following:Get medical care right away. Have a trusted friend take you to a hospital emergency room. Don't urinate, douche, bathe, brush your teeth, wash your hands, change clothes, or eat or drink before you go. These things may give evidence of the rape. The hospital will use a "rape kit" to collect evidence. Call the police from the hospital. Tell the police exactly what you remember. Be honest about all your activities. Remember, nothing you did — including drinking alcohol or doing drugs — can justify rape. Ask the hospital to take a urine (pee) sample that can be used to test for date rape drugs. The drugs leave your system quickly. Rohypnol stays in the body for several hours, and can be detected in the urine up to 72 hours after taking it. GHB leaves the body in 12 hours. Don't urinate before going to the hospital. Don't pick up or clean up where you think the assault might have occurred. There could be evidence left behind — such as on a drinking glass or bed sheets. Get counseling and treatment. Feelings of shame, guilt, fear, and shock are normal. A counselor can help you work through these emotions and begin the healing process. Calling a crisis center or a hotline is a good place to start.
This answer is based on source information from the National Women's Health Information Center.