Three Cases of Reported Improvement in Microsmia and Anosmia Following Naturalistic Use of Psilocybin and LSD

Olfactory dysfunction (OD), including anosmia (loss of smell) and microsmia (reduced smell), is associated with reduced quality of life across mood, safety, social engagement, and appetite. Common causes include sinonasal disease, trauma, and post-infectious injury; recent attention has focused on post-infectious OD because of the frequency and persistence of smell loss following COVID-19 infection. Existing treatments for post-infectious OD are limited: olfactory training has some supporting randomised evidence but modest benefit, while pharmacological and procedural options (topical/oral steroids, antibiotics, alpha-lipoic acid, stellate ganglion block, surgery) lack consistent efficacy for sensorineural forms of OD. Kovacevich and colleagues report what they describe as the first three cases in the medical literature of subjective or objective improvement in anosmia/microsmia following naturalistic use of classic psychedelics (psilocybin and LSD). The authors note that social and traditional media have suggested similar improvements and argue biological plausibility via serotonergic effects, enhanced neuroplasticity, and anti-inflammatory actions of classic psychedelics. The paper aims to present these three cases, document available objective testing where present, and explore potential mechanisms to motivate further formal investigation.

This paper is a clinical case series of three individuals who reported improvement in olfactory function following naturalistic psychedelic use. All three patients provided informed consent for publication; the project was exempted from institutional review board oversight at the reporting centre. Data were derived from patient history, self-reported timelines, and, where available, objective olfactory testing performed by the patients or investigators after the psychedelic exposure. Olfactory identification was assessed using the University of Pennsylvania Smell Identification Test (UPSIT), a validated 40-item scratch-and-sniff measure; olfactory threshold testing was not performed. Subjective psychedelic phenomenology was characterised retrospectively using the Mystical Experience Questionnaire (MEQ30), a 30-item scale whose scores can indicate a ‘‘complete mystical experience’’ when subscale thresholds are met. Because these were naturalistic, non-interventional reports, there was no experimental control, randomisation, or pre-specified analytic plan: outcomes are descriptive and observational. The authors recorded dosing and regimen details, prior psychedelic and substance use, medical history relevant to olfaction, timing of symptom onset and recovery, and MEQ30 and UPSIT scores when available. No formal statistical analyses were performed.

All three cases described subjective improvement in smell following psychedelic exposure, but objective data were limited and mixed. Case 1: A 35-year-old man (Mr H) developed partial ageusia and microsmia after a respiratory infection (COVID antigen test negative). About 30 days after symptom onset he self-administered the UPSIT and scored 33/40, consistent with mild microsmia (12th percentile). Later that day he ingested 6 g of dried psilocybin-containing mushrooms. He retrospectively completed the MEQ30 (score 41), not meeting criteria for a complete mystical experience. Near the end of the psychedelic experience he noticed improved smell and taste. Twelve days post-use his UPSIT score improved to 36 (36th percentile), indicating normosmia; at 49 days it was 35 (27th percentile), still in the normosmic range. He reported ongoing subjective improvement at 49 days. Case 2: A 23-year-old woman (Ms R) had lifelong total anosmia attributed to olfactory nerve damage. At age 21 she underwent a guided LSD session (100 µg orally) with Reiki performed by a guide; she retrospectively scored 147 on the MEQ30, consistent with a complete mystical experience. During the session she distinctly perceived the smell of orange and peppermint, and this new ability persisted beyond the session. Over several weeks the improvement diminished and plateaued but, by subjective report, remained better than her prior baseline. Two years later she was administered the UPSIT and scored 17/40 (<5th percentile), which classifies as anosmia; no pre-LSD UPSIT was available for comparison. Case 3: A 22-year-old woman (Ms E) developed acute total anosmia confirmed by PCR-positive COVID-19 infection and had persistent anosmia for 6 months. She self-administered nightly microdoses of 0.1 g dried psilocybin mushrooms for three consecutive nights with the stated intention of restoring smell. She reported no overt psychedelic effects and scored 2 on the MEQ30. On the fourth day after initiating microdosing she began to detect certain odours (nail polish, scented candles, soaps, rain). Two months after the microdosing episode her UPSIT score was 15/40 (<5th percentile), i.e. anosmia, but she reported continued subjective improvement at 2 months and up to 8 months post-exposure. Across the three cases, only case 1 had both pre- and post-exposure UPSITs showing an objective shift from mild microsmia to normosmia. Cases 2 and 3 lacked pre-exposure UPSITs, and their post-exposure UPSITs remained in the anosmic range despite subjective reports of improvement. No olfactory threshold testing was performed. No serious adverse events were reported in these extra-clinical accounts.

The authors interpret these cases as preliminary evidence that classic psychedelics may, in some instances, be associated with improvement in anosmia or microsmia. They stress that objective evidence is limited: only one patient demonstrated measurable improvement on UPSIT after psilocybin, and the other two patients reported sustained subjective gains despite post-exposure UPSIT scores remaining in the anosmic range. Durability beyond seven weeks is uncertain; case 1 showed stability at seven weeks, case 2 reported partial persistence two years later by subjective account, and case 3 reported ongoing limited improvement up to eight months. Several biological mechanisms are proposed to account for the observations. Serotonergic modulation is highlighted because classic psychedelics are 5-HT2A agonists and serotonin influences olfactory processing at multiple CNS loci, including the olfactory bulb and glomerular layer; animal studies show LSD binding in olfactory regions and modulation of olfactory bulb activity. Enhanced neuroplasticity following psychedelic exposure is another candidate mechanism: psychedelics have been linked to rapid changes in synaptic plasticity through pathways involving intracellular 5-HT2A signalling, TrkB, AMPA receptor-related gene expression, and mTOR pathways, which could, in theory, help compensate for sensorineural olfactory damage. Anti-inflammatory effects of psychedelics are also discussed as a plausible mechanism in post-infectious cases, given inflammation's putative role in COVID-19-related olfactory dysfunction and preclinical evidence that 5-HT2A agonists can have anti-inflammatory properties. The authors also note an alternative explanation for the discordance between UPSIT results and subjective reports: improvements might reflect higher-order perceptual or cognitive changes—enhanced recognition or changed valence of olfactory percepts—rather than changes in peripheral olfactory sensitivity, since the UPSIT assesses identification and not detection threshold. They draw a parallel with case reports of improved colour discrimination after psychedelics, which may reflect altered higher-order perceptual processing rather than changes to primary sensory apparatus. Key limitations are acknowledged: spontaneous recovery after recent infection could explain case 1's improvement, pre-exposure objective data are lacking for cases 2 and 3, etiologies differed across cases (olfactory nerve damage versus post-infectious), and threshold testing was not performed. Given these limitations, the authors present these cases as preliminary and advocate for more formal scientific investigation — including controlled trials or systematic observational studies — to evaluate whether psychedelics can reproducibly and safely improve olfactory dysfunction and to elucidate mechanisms.