Patients occasionally experience sexual hallucinations while under conscious sedation

Although there's been much discussion about the relationship between anaesthesia and these hallucinations, awareness of this side effect amongst both clinicians and academics remains somewhat low. The consequences of clinicians being accused of sexual misconduct that was in actuality a hallucination can extremely be serious; some have lost their licenses to practice, despite being acquitted.

But even with the high-stakes consequences of sexual hallucinations, there has been relatively little published on the matter, making it difficult to understand the phenomenon as a whole. However, Alex Orchard and Ellie Heidari at Guy's and St Thoman's NHS Trust and King College London have synthesised the scattered existing literature on sexual hallucinations while under conscious sedation in their recent review. The resulting paper not only theorises as to risk factors which may prompt such hallucinations, but also suggests practical ways that may help clinicians avoid and manage their occurrence.

The team's search for peer-reviewed papers covered almost five decades of publications, from 1975 to 2020, which contained references to sexual hallucinations, conscious sedation, and dentistry or anaesthetics. In all, 28 papers were included in their review, 20 of which were from the UK, four from the US, two from China, and one from both Norway and Australia.

A selection of sedative drugs were mentioned in the chosen articles — namely, benzodiazepines (13 papers), propofol (12 papers) and nitrous oxide (three papers) — with 15 papers mentioning use of a combination of sedatives. Some of the chosen publications also provided estimates of the prevalence of sexual hallucinations in patients under the influence of each of these drugs. These, however, vary widely. For example, an included paper from 1986 by JW Dundee estimated that a low dosage of midazolam (a benzodiazepine) would produce this side effect in one in between 50,000 and 100,000 patients. At higher doses, this same paper concluded that as many as one in 2000 patients may experience some form of sexual hallucination. Some research into propofol by Zhiyong Yang and Bin Yi in 2016 was much more generous in its estimates, stating that a high dose could produce such hallucinations in as many as 10% of patients.

Twelve of the papers included in this review focused on dental treatment, whereas others centred around endoscopy (six papers), gynaecological and urinary procedures (seven papers), and breast or orthopedic surgery (one each). Though this covers quite a wide array of procedures and specialities, the majority of papers make mention of a "procedure-specific stimulus" which, in combination with sedation, was associated with sexual hallucinations. For example, in the case of dentistry, suction tubes to clear saliva and blood may be misinterpreted by patients in states of altered consciousness.

Patients experiencing such hallucinations may behave in particular ways under sedation, such as making references to past sexual encounters, making advances towards clinicians, or declaring that the clinician is touching them inappropriately. Interestingly, though sexual hallucinations while under anaesthesia have been documented in both men and women, men tend to report more vivid and positive hallucinatory experiences than women.

This may be explainable by the fact that women, generally speaking, are very aware of the dangers posed by non-consensual advances, and therefore may be more readily fearful. However, since ages and genders of those included in the literature vary so widely, it's not yet possible to determine if these factors significantly affect the prevalence of these hallucinations.

The authors bring these insights from previous literature together into a theory of a relationship between sedation, stimuli, and patient risk factors. Though they believe that sedation may be enough to prompt these hallucinations on its own, there is likely an additive effect of procedure-specific stimuli (eg. vaginal swabs, suction tubes) and patient predisposition to hallucinations (eg. mental health conditions, drug use).

In order to protect against the occurrence of sexual hallucinations, the authors recommend adhesion to existing professional guidelines for conscious sedation. These range from conducting pre-assessments of patients for risk factors associated with hallucinations, the presence of a third party to witness procedures, and checking in with patients about their experiences after the procedure concludes. In the event that sexual hallucinations have occurred, however, the authors recommend debriefing the patient in a sensitive manner, ideally in the presence of a third party that witnessed the procedure, and recording the side effect in medical notes to inform future clinicians.

As this side effect is relatively rare (or at least rarely reported), the quality and strength of evidence included in this review understandably leaves something to be desired. A prime example of this is the statement that dosages exceeding 0.1mg/kg of midazolam increases the likelihood of sexual hallucinations; as the team points out, this claim has been regularly made in the literature, but originated from a single author more than 20 years ago, and has seemingly been unchecked since. The majority of peer-reviewed papers on this phenomenon also come from the UK, so future research is needed to look at its prevalence in other cultures.

Even so, given the high — and potentially career ending — costs associated with accusations of sexual hallucinations, this review will be welcomed by many. Not only will it undoubtedly increase awareness of the phenomenon and procedures to ensure continued patient and doctor wellbeing, it may attract some additional research to further validate and understand what causes these hallucinations to occur.

Further reading

– Sexual hallucinations during conscious sedation for dentistry – an update of the phenomenon

About the author

Emma L. Barratt (@E_Barratt) is a staff writer at BPS Research Digest