Secondary Logo

Journal Logo

AAPA Members can view Full text articles for FREE. Not a Member? Join today!
Special Article

Beyond roofies

Drug- and alcohol-facilitated sexual assault

Thompson, Katherine M. MCHS, PA-C, FE

Author Information
Journal of the American Academy of Physician Assistants: January 2021 - Volume 34 - Issue 1 - p 45-49
doi: 10.1097/01.JAA.0000723940.92815.0b
  • Free



Sexual assault remains a prevalent problem in our society, with 25% to 30% of women and one in eight men experiencing it at least once in their lifetime.1 Although sexual assault often is perpetrated through force or fear, substances often are involved. Most researchers agree that at least half of sexual assaults involve alcohol, other substances, or a combination of alcohol and other substances.2 In college and younger populations, this percentage increases exponentially to almost 90% of assaults involving substances.3 Alcohol and drug use is widely acknowledged to affect the user's ability to respond to a variety of situations, including operating a motor vehicle and exercising sound judgment. Despite this acknowledgment, substance use is widely tolerated in our society, particularly the use of alcohol as a social lubricant to our often disparate backgrounds and experiences. The use of substances in sexual assault, whether the substances are used voluntarily or involuntarily by the victim, changes the aftermath and recovery process significantly, affecting the way memories are processed and recalled, the chances of developing significant mental health complications, and the disclosure reactions that the survivor receives. This article provides an overview of substance use in sexual assault and the nuances of interviewing and testing, so that clinicians can provide the best possible care to survivors.


In a drug- or alcohol-facilitated sexual assault (DAFSA), the victim is rendered unconscious or unable to resist.4 This is not mutually exclusive and it is possible to have both qualities at different points during the assault lead-in, assault progression, and postassault.

In DAFSA-VI, victims voluntarily ingest a substance and no substances are known or suspected to have been given against their will or without their knowledge. Victims have at least one incapacitation symptom. The definition for incapacitation is broad, but can include symptoms such as slurred speech, vomiting, unsteady gait, and decreased decision-making capacity. In DAFSA-I, victims knew or learned that they had been given substances against their will or without their knowledge, suspected this, and have at least one incapacitation symptom.

DAFSA is largely, but not always, considered criminal activity even if the substance use is consensual. The substances used can be legal, illegal, or a combination. An excellent example of a combination use is dispensing an illegal liquid into alcohol, which the victim ingests without knowing about the tampering.

Box 1
Box 1

By definition, DAFSA substances are those that render the victim:

  • unconscious
  • very passive
  • powerless to resist sexual advances
  • unable to fight off an attacker
  • incapable of thinking clearly or making appropriate decisions and unable to say no
  • with little or no memory of what happened
  • still able to participate in the sex act to some extent
  • to act without inhibition, often in a sexual or physically affectionate way.4


A common misconception is that the presence of DAFSA in our society is a modern problem, perhaps facilitated by our increased social acceptance of substance use, substances being used by younger populations (including college-age people), and the presence of designer drugs that are well-designed for committing these types of assault.

However, the first documented case of DAFSA was in 1900, with a case involving a young woman who ingested a beverage spiked with chloral hydrate, which caused syncope and death. Before her death, the bartender and the acquaintances raped her.5,6

Most studies acknowledge that between 52% and 83% of completed sexual assaults are DAFSA.7 This is largely population-dependent, with general population studies falling at the low end of this range and studies involving predominantly college-age persons having much higher rates.2,3 As an important point of clarification, many of the studies that are published about the cause of sexual assault do not do an adequate job of distinguishing substance-related assaults from other forcible sexual assaults; they often fail to distinguish voluntary and involuntary substance abuse, indicating that incidences of DAFSA may be higher than what is reported.4

The most commonly used substance is alcohol, which present in one-third to three-quarters of all sexual assault cases, including half of all college student assaults.4,8 In one study, only two women out of the entire study population were found to have other substances in their blood or urine besides alcohol at the time of assault.7

Therefore, although other substances, such as GHB (gamma hydroxybutyrate), benzodiazepines, and “roofies” (rohypnol), are widely publicized by mainstream media as being the predominant substances to be aware of, they are involved in 5% or less of DAFSA cases, making them the exception and not the rule.9


Rape began as a crime of property, not against a person, being defined in US law as “carnal knowledge by a man of a woman not his wife.”10 This was revised to the current definition of rape in 2013, which now stands as “penetration of vagina or anus (however slight) by a penis, digit, or other object against a person's will.”10 The revised definition was helpful in classifying the crime as an interpersonal crime, removing the sexes of the victim and perpetrator from consideration, and including other forms of penetration besides vaginal. In 1993, spousal rape was acknowledged as a crime.11

Despite the prevalence of drug- and alcohol-facilitated crimes, legal loopholes abound in the prosecution of these crimes. All jurisdictions reporting have statutes that cover unconscious victims, but only 10 states have statutes that govern voluntary intoxication that results in sexual assault. Additionally, 40 jurisdictions surveyed have statutes that cover the “inability to appraise” or the “inability to control conduct” that could potentially cover DAFSA, although it is not clearly defined.11


Several qualities make a substance particularly desirable for use in DAFSA: widely availability (with or without a prescription), unlikely to be detected in routine screening (or disregarded as a voluntary ingestion in routine screening), and possessing amnestic or memory-altering properties.12

Table 1 lists other commonly used substances in DAFSA and their overall clinical effects. Substances most frequently highlighted by the media may not be the substances being used the most often. Good examples of this disparity include rohypnol and GHB.2,12

TABLE 1. - Substances commonly used in DAFSA
Substance How used Effect Signs and symptoms Half-life or processing time
Alcohol Alone, vehicle CNS depressant Confusion, memory loss, reduced inhibitions, loss of consciousness 20 mg/dL per hour
Benzodiazepines Alone, combination Increase GABA inhibitory effect Drowsiness, confusion, anterograde amnesia, loss of consciousness Blood: 48 h Urine: 96 h (variable)
Muscle relaxants Alone, combination Various effects; mechanism of action often unclear Sedation, dry mouth, dizziness 18 hours
GHB Alone, combination CNS depressant Drowsiness, deep sleep, hypotonia, increased sensuality, amnesia, loss of consciousness Maximum detection in urine: 0-3 h

Substances that are listed as being used alone are those in which that is the only substance that is found in a victim's body after the assault, indicating that is the sole substance employed in the perpetration of the crime. Those that are used as a vehicle indicate that another substance is conveyed into the body by the vehicle substance, as is the case with GHB and alcohol. Those that are listed as combination indicate that they are commonly employed in addition to other substances and less often used alone, although in none of these cases are these findings absolute, especially given the likelihood that substance use is a combination between voluntary and involuntary.4,12,13

Many DAFSAs are premeditated, from elaborate schemes involving bar employees to simply ensuring that a victim is intoxicated, but in all cases, the availability and cost of the substance being used plays a heavy deciding factor. For example, drugs like MDMA (Ecstasy) may produce a very desirable effect in the victim, but likely is expensive, is easily tested for, and is not easily dispensed without a victim's knowledge. By comparison, zolpidem is among the top 10 branded drugs prescribed (from a study of years 2004-2006), induces anterograde amnesia in victims, and is unlikely to be detected because of its short half-life and the lack of routine screening.13


Alcohol is by far the most common substance used in the perpetration of DAFSAs, both because of its availability and its ease of use.8 However, the statistics on the frequency of use of alcohol in DAFSA are considered to be skewed because it often is ingested voluntarily. This voluntary ingestion can then be used to introduce other substances for the perpetration of an opportunistic assault.8

The clinical effects of alcohol are dose- and time-dependent, and universally affect both the person's cognitive and psychomotor functions. Lower doses and/or early intoxication cause confusion, impaired judgment, cognitive impairment, reduced inhibitions, and lack of muscle coordination.8 Higher doses and/or late intoxication cause drowsiness, loss of consciousness, nausea and vomiting, coma, and death.8

Alcohol depresses the central nervous system (CNS) in a manner similar to hypnotics, opioids, and other CNS depressants, but its efficacy is related to multiple factors, including the amount that is ingested and the size and overall tolerance of the drinker.8 Alcohol is absorbed from the mucosal surfaces of the gastrointestinal tract by simple diffusion, and thus, the absorption rate is directly proportional to the concentration gradient.14

Alcohol is widely available in a number of different forms and strengths, is socially acceptable for use, and is relatively cheap. In one British study, alcohol was found in up to 81% of samples collected from victims of sexual assault within 12 hours of the assault.8 Alcohol also is popular for DAFSA because it lowers the drinker's inhibitions, allows other substances to be dissolved in it fairly easily, and often is flavored, reducing the taste or odor of other substances. Women who drink alcohol were found to almost universally ignore danger signals of situations that they may otherwise take note of if they were not under the influence of alcohol.8 Alcohol is so very prevalent in our society that it is present in almost every DAFSA and it remains difficult to legally untangle from the consensual use of alcohol.


One of the most interesting DAFSA topics is that of the memory changes associated with the consumption of DAFSA substances. These changes are in addition to the changes in memory processing secondary to traumatic events.

Normal memory formation has three stages: encoding, retention and storage, and retrieval. Encoding involves the initial registration and interpretation of stimuli, retention and storage involves the filing of memories in various sections of the brain and whether they are defined as short- or long-term memories, and retrieval governs how the memories are accessed after storage.8

The excessive use of alcohol is positively associated with the presence of blackouts, which are not to be confused with loss of consciousness. A blackout is defined as a loss of memory or a period of amnesia without a loss of consciousness.15 During a blackout, the person has a loss of memory that is typically defined as one of two types: fragmentary or en bloc. Fragmentary memory loss occurs at moderate to high levels of blood alcohol content, is more common than en bloc memory loss, and happens when memory traces are formed but are more difficult to access. Fragmentary memory loss is thought to be related to frontal lobe functions, and is thought to be mostly an issue of encoding and retrieval.15

En bloc memory loss has a definitive beginning and end point, and an otherwise complete absence of memory. Typically, it is described as a feeling of lost time, and is not state-dependent, although it requires a very significant amount of alcohol to effectively disrupt the limbic system enough to permanently prevent long-term memories from encoding. This type of memory loss typically only occurs at blood alcohol levels higher than 0.24%.15

Episodic memory also is affected by alcohol ingestion. Episodic memory helps us to define the interrelated characteristics that make up a memory, such as time, place, and other contextual clues. Additionally, in the hippocampus, there are place cells that also are involved in effective memory coding and retrieval, and in the contextual clues associated with memories. These cells are significantly altered by the ingestion of alcohol. The most common effect by these combined areas is a vague series of memory threads that the person cannot tie together or connect the dots. For example, a DAFSA survivor will describe remembering their own hands on someone's belt, but not whether it was consensual, how they were feeling at the time, whether that occurred at their house or somebody else's, or to whom the belt belonged.8,15

Other substances besides alcohol affect memory and awareness.12 GHB has been shown to provoke amnesia and also decrease inhibitions. Benzodiazepines cause anterograde amnesia and nonbenzodiazepine hypnotics tend to produce retrograde amnesia.11,16


In most sexual assault programs, the element of human judgment is removed by having a policy to test all survivors of sexual assault for common DAFSA substances, regardless of the results of their interview.4 This healthy suspicion allows for the best possible opportunity for testing, because most common substances are metabolized almost completely within 72 hours of ingestion. As a common example of time frame, the median time from assault to examination was 18 hours. But 96% of a drug with a half-life of 3 hours would be metabolized after 15 hours (that is, five half-lives of the drug), rendering this fairly generous half-life almost or completely unrecognizable in common screening at 18 hours.12 As an extreme example, GHB has a half-life of 0.5 to 1 hour, rendering it almost undetectable shortly after a sexual assault.16

Properly collecting samples for testing is important because improper collection can fail to halt the metabolization of drugs and prevent the adequate detection of substances of criminal importance. Collect blood using gray-top tubes, which contain sodium fluoride and potassium oxalate (anticoagulants) and refrigerate the tubes after collection. Before performing venipuncture, clean the area using betadine, iodine, or another nonalcoholic skin cleaner to avoid contamination of the sample.4,12 Collecting a urine sample is particularly important for clinicians who may see patients before they see a specialized forensic examiner; the first void available can provide a much higher yield for detection of many substances than subsequent voids.9 These samples also should be preserved with sodium fluoride and refrigerated.

Other methods of testing for DAFSA substances typically are reserved for specialized forensic testing centers. They include testing hair samples, which can preserve evidence of DAFSA substances up to 3 to 6 weeks after the crime occurs.4 Traditional drug screening panels used in acute care settings frequently do not include relevant substances such as GHB and certain metabolites, limiting their usefulness for DAFSA screening, and should be used judiciously. When in doubt, preserve samples rather than wasting them on screening tests that will not adequately profile the submitted substance.9


Sexual assault results in significant emotional and mental health complications, including depression, higher rates of posttraumatic stress disorder (PTSD), anxiety, chronic pain syndromes, fibromyalgia, and higher rates overall of chronic disease.17,18

One of the most notable differences between DAFSA and other violent crimes is the lack of direct research in the area. DAFSA often is not independently studied, making it difficult to accurately track the differences in crimes. However, the consensus is that PTSD tends to be more severe in survivors of DAFSA crimes, and the severity inversely correlates with the amount of memory that the survivor has of the crime: The more the survivor remembers, the less severe the PTSD tends to be.19,20 This is thought to be related to the traumatic, disordered processing of memory discussed earlier in the article that surrounds both traumatic events and the physiology of using substances, including alcohol. Additionally, the lack of memory about a traumatic event, especially one involving personal violence, may be very disturbing because of the knowledge that unknown events occurred outside of the person's capacity of awareness.20

The other most notable difference between non-DAFSA and DAFSA crimes is the amount and type of self-blame that victims may experience. Self-blame typically is divided into two subtypes: characterologic and behavioral. Characterologic self-blame is represented in statements such as This happened to me because I am a bad person and I must have done something to deserve bad things happening to me. Behavioral self-blame is represented in statements such as I shouldn't have had so much to drink or I shouldn't have walked home alone at night. In DAFSA crimes, particularly those with a component of willing drug or alcohol ingestion, behavioral and overall self-blame tends to be higher.17 Concurrently, DAFSA victims tend to experience higher levels of stigma, fear over negative reactions to disclosure, and problem drinking.17


Survivors of DAFSA crimes face significant constraints to reporting, including self-doubt, fear of recrimination, fear of punishment for the use of legal or illegal substances, or simply the lack of adequate memory of the assault. Many survivors can only offer statements such as “I just know something happened.” Prosecution commonly uses voluntary substance abuse to discredit and disparage victims in the court of law. Understanding and becoming sensitive to these preexisting barriers, understanding the limitations and best practices in testing and detection, and understanding the complications that these survivors face can make clinicians better, more sensitive, and more flexible healthcare providers.


1. Rape, Abuse, and Incest National Network. Statistics. Accessed October 5, 2020.
2. Richer LA, Fields L, Bell S, et al. Characterizing drug-facilitated sexual assault subtypes and treatment engagement of victims at a hospital-based rape treatment center. J Interpers Violence. 2017;32(10):1524–1542.
3. Carey KB, Durney S, Shepardson RL, Carey MP. Incapacitated and forcible rape of college women: prevalence across the first year. J Adolesc Health. 2015;56(6):678–680.
4. Dinis-Oliveira RJ, Magalhäes T. Forensic toxicology in drug-facilitated sexual assault. Toxicol Mech Methods. 2013;23(7):471–478.
5. LeBeau MA, Montgomery MA. The frequency of drug-facilitated sexual assault investigations. Forensic Sci Rev. 2010;22(1):7–14.
6. LeBeau MA, Montgomery MA. Challenges of drug-facilitated sexual assault. Forensic Sci Rev. 2010;22(1):1–6.
7. Testa M, Livingston JA, Vanzile-Tamsen C, Frone MR. The role of women's substance use in vulnerability to forcible and incapacitated rape. J Stud Alcohol. 2003;64(6):756–764.
8. Kerrigan S. The use of alcohol to facilitate sexual assault. Forensic Sci Rev. 2010;22(1):15–32.
9. DeVore HK, Sachs CJ. Sexual assault. Emerg Med Clin North Am. 2011;29(3):605–620.
10. US Department of Justice, Federal Bureau of Investigation. Crime in the United States, 2011.,Sodomy%20(NIBRS%20Offense%20Code%2011B). Accessed October 7, 2020.
11. Kruttschnitt C, Kalsbeek WD, House CC. Panel on Measuring Rape and Sexual Assault in Bureau of Justice Statistics Household Surveys. Committee on National Statistics. Division on Behavioral and Social Sciences and Education. Estimating the Incidence of Rape and Sexual Assault. Washington, DC: National Academies Press; April 7, 2014.
12. Carter LP. Potential impact of drug effects, availability, pharmacokinetics, and screening on estimates of drugs implicated in cases of assault. Drug Test Anal. 2011;3(9):586–593.
13. Gautam L, Sharratt SD, Cole MD. Drug facilitated sexual assault: detection and stability of benzodiazepines in spiked drinks using gas chromatography-mass spectrometry. PLoS One. 2014;9(2):e89031.
14. Brouwer IG. The Widmark formula for alcohol quantification. SADJ. 2004;59(10):427–428.
15. Connell M. Expert testimony in sexual assault cases: alcohol intoxication and memory. Int J Law Psychiatry. 2015;42–43:98–105.
16. Fedina L, Holmes JL, Backes BL. Campus sexual assault: a systematic review of prevalence research from 2000 to 2015. Trauma Violence Abuse. 2018;19(1):76–93.
17. Littleton H, Grills-Taquechel A, Axsom D. Impaired and incapacitated rape victims: assault characteristics and post-assault experiences. Violence Vict. 2009;24(4):439–457.
18. Littleton H. Sexual victimization and somatic complaints in pregnancy: examination of depression as a mediator. Womens Health Issues. 2015;25(6):696–702.
19. Zinzow HM, Resnick HS, Amstadter AB, et al. Drug- and alcohol-facilitated, incapacitated, and forcible rape in relation to mental health among a national sample of women. J Interpers Violence. 2010;25(12):2217–2236.
20. Zinzow HM, Resnick HS, Barr SC, et al. Receipt of post-rape medical care in a national sample of female victims. Am J Prev Med. 2012;43(2):183–187.

sexual assault; rape; substance use; interpersonal violence; domestic violence; alcohol

Copyright © 2021 American Academy of Physician Assistants