Long-term Amelioration of OCD Symptoms in a Patient with Chronic Consumption of Psilocybin-containing Mushrooms

Obsessive Compulsive Disorder (OCD) is described as a chronic neuropsychiatric disorder marked by intrusive thoughts and repetitive behaviours that impair daily functioning, with a lifetime prevalence of about 2–3%. First-line treatments, principally selective serotonin reuptake inhibitors (SSRIs), fail to produce adequate response in an estimated 41–43% of patients, leaving a substantial treatment-resistant population. Previous case reports and some experimental data have suggested that psilocybin and psilocybin-containing mushrooms may reduce OCD symptomatology, but evidence remains limited and heterogeneous. This paper presents a single-case report of an adult male with long-standing, treatment-resistant OCD who experienced a clinically meaningful reduction in symptoms following consumption of psilocybin-containing mushrooms. The aim is to document the clinical course, measured symptom change, and tolerability in this individual, and to situate the observation within existing animal and human findings about serotonergic mechanisms and psychedelic compounds in OCD treatment.

This work is a single-patient case report. The extracted text provides clinical details for Mr J.C., a 30-year-old, 90-kg married male who had been treated for OCD in a clinic for 1 year and had a 10-year history of disabling symptoms including obsessive thoughts, compulsions, checking behaviour, rumination, worry and anxiety. Prior pharmacological treatments over several years were documented and included multiple SSRIs and SNRIs (sertraline, escitalopram, fluoxetine, paroxetine, venlafaxine, duloxetine, milnacipran), mirtazapine, and adjunctive use of celecoxib at one point. Intranasal ketamine was also tried (100 mg/week for 3 weeks) without benefit. At the time of the reported psilocybin use he was receiving fluoxetine (up to 60 mg/day), fluvoxamine (up to 300 mg/day) and risperidone (up to 1 mg/day), described as partially effective. Intervention details are observational: nine months into the current regimen the patient purchased locally identified "derrumbe mushrooms" (reported as Psilocybe caerulescens) in Oaxaca, Mexico, and ingested approximately 2 g of dried mushrooms at home with a friend present. He reported an hour of dissociation without frank hallucinations after the initial dose, complete disappearance of OCD symptoms during that hour, and marked reduction for about 2 weeks thereafter. Subsequently he self-administered approximately 2 g of dried mushrooms every 2 weeks, each episode followed by a similar period of symptom reduction. No formal blinding, randomisation or control was possible given the case-report design. Outcomes were measured clinically and with the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), a standard clinician-rated instrument assessing OCD severity. Y-BOCS scores were recorded 3 days before the first mushroom ingestion, and at 1 and 6 months after the initial ingestion. Regular clinical follow-up visits occurred approximately every 2 months. Safety and adverse effects were monitored by patient report during clinic visits.

Before the first mushroom ingestion the patient scored 35 on the Y-BOCS, categorised as extreme OCD. One month after initial ingestion his Y-BOCS score was 18 (moderate OCD), and at 6 months it was 13 (mild OCD), representing a 63% reduction from baseline. Clinically, the patient reported that obsessive thoughts, compulsions, rumination, worry, anxiety and checking behaviour had been significantly reduced, and that he was able to perform most daily tasks and work without interruption, with meaningful improvement in wellbeing and quality of life. Following the first 2 g dose, the patient experienced about 1 hour of dissociation without hallucinatory effects; symptoms completely disappeared during that hour and were markedly reduced for around 2 weeks. He then self-administered roughly 2 g of dried mushrooms every 2 weeks, with each administration followed by a similar period of symptom reduction. No further dissociation or other adverse or hallucinogenic effects were reported during subsequent uses. The patient continued his prescribed pharmacotherapy (fluoxetine, fluvoxamine, risperidone) while consuming the mushrooms as an adjunct; clinic visits every 2 months elicited no reports of side-effects or distress related to mushroom use. Six months after the initial use he continued to report meaningful symptom reduction.

The authors interpret the clinical improvement in light of serotonergic pharmacology: psilocybin is an agonist at 5-HT1A and 5-HT2A/2C receptors, and preclinical OCD models have shown reduced compulsive behaviour following psilocybin or other agents that enhance 5-HT2 receptor-mediated activity. They note that the patient did not experience hallucinations, which they suggest could be due to concurrent fluoxetine (chronic fluoxetine can desensitise 5-HT2A receptors) and risperidone (an inverse agonist at 5-HT2A receptors). Despite potential receptor desensitisation or blockade, a meaningful clinical response was observed, leading the authors to propose that the anti-OCD effect may be at least partly independent of full 5-HT2A-mediated psychedelic effects; the brief dissociative episode after the first dose, however, leaves open the possibility of partial 5-HT2A activation contributing to benefit. Lugo-Radillo and colleagues place the case alongside prior case reports and a small trial in which psilocybin reduced OCD symptoms, arguing that placebo explanations are unlikely given the patient’s long history of non-response to many treatments and the sustained, repeated symptomatic improvements following mushroom ingestion. The authors also mention that other psychoactive constituents in whole mushrooms might augment the effect of psilocybin. Safety observations in this case were favourable; the authors remark that psilocybin-containing mushrooms have been used in some communities in Oaxaca for ritual and medicinal purposes and are considered relatively safe when used in that context. They acknowledge that randomised controlled trials are ongoing and necessary to determine efficacy and safety more definitively. The extracted text ends mid-sentence, and the final concluding remarks or any further limitations reported by the authors are not present in the provided extraction.