A 49-year-old daily cannabis user developed delusional infestation (Ekbom syndrome), believing parasites were crawling under his skin, which resolved with antipsychotic treatment.
Clinicians, dermatologists seeing unexplained skin complaints, and people interested in unusual psychiatric presentations linked to cannabis.
Decades of daily use preceded onset
What the researchers found
A man with decades of daily cannabis use presented with persistent pruritus, tactile hallucinations, and a fixed belief that parasites infested his skin. All dermatological, neurological, and imaging tests were normal. The presentation was consistent with cannabis-induced psychotic disorder manifesting as somatic delusions. Treatment with olanzapine and psychoeducation led to gradual improvement.
Why it matters
Cannabis-induced psychosis typically presents with paranoia or hallucinations, not somatic delusions. This unusual presentation could be missed or misdiagnosed, particularly if clinicians do not consider substance-induced causes for delusional infestation.
The numbers in context
49-year-old male with long-standing daily cannabis use. Normal dermatological, neurological, and lab findings. Normal cranial CT. Treated with olanzapine with gradual symptomatic improvement.
How the study worked
Single case report with comprehensive workup including dermatological assessment, neurological examination, laboratory investigations, and cranial CT to exclude organic causes.
What this study cannot tell us
Single case report cannot establish causation. The patient may have had underlying vulnerability to psychosis. Long-standing daily use makes it difficult to determine what specific change (if any) triggered the onset.
How to read the evidence
Single case report. Informative for clinical awareness but cannot establish causation or prevalence.
When this study was published
2026 case report.
The bigger picture
Delusional infestation is more commonly associated with stimulant use or primary psychiatric conditions. This case broadens the recognized spectrum of cannabis-induced psychotic presentations and underscores the importance of thorough substance use history in unusual psychiatric cases.
Questions still open
- How often do atypical somatic presentations of cannabis-induced psychosis go unrecognized? Could increasing potency of cannabis products contribute to more unusual psychotic presentations?
Common questions
What is delusional infestation?
Is this a common effect of cannabis?
Read the original research
Psychotic Risk Associated With Cannabinoid Use: A Case Report of Ekbom-Like Delusional Infestation.
Cureus, 18(1), e100945
Citation
Pao Trigo, Miguel; Cavaco Rogrigues, Joana; Luz, Bruno; Sá Couto, Joaquim; Mota Oliveira, Marco. (2026). Psychotic Risk Associated With Cannabinoid Use: A Case Report of Ekbom-Like Delusional Infestation.. Cureus, 18(1), e100945. https://doi.org/10.7759/cureus.100945
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