Microdosing psilocybin for chronic pain: a case series

Interest in medical applications of classic serotonergic psychedelics, particularly 5-HT2A agonists such as psilocybin, has risen due to recent trials showing benefit in treatment-resistant psychiatric disorders. Earlier clinical work and preliminary contemporary reports also suggest these agents can have analgesic effects, including in migraine/cluster headache and phantom limb pain. However, full-psychedelic (hallucinogenic) dosing is often accompanied by profound perceptual and cognitive effects that limit routine clinical utility, and there are few controlled trials of psychedelics for chronic pain. Microdosing—administration of sub-psychedelic amounts—has been less studied; one prior randomized trial found low-dose LSD attenuated acute pain in healthy volunteers, but systematic characterisations of microdosing for chronic pain are lacking. This case series, presented by Lyes and colleagues, aims to document the experiences of three patients who self-administered low (sub-hallucinogenic) doses of psilocybin-containing mushrooms to manage chronic neuropathic pain. The investigators sought to describe dosing patterns, onset and duration of analgesia, perceived benefits and off-target effects, and the role of psilocybin as an adjunct to physical therapy or in reducing opioid use, in order to inform future controlled research.

The study used qualitative clinical interviews conducted via online video with self-referred patients who contacted the UC San Diego Pain Medicine service after self-administering psilocybin for chronic pain. Of five individuals who made contact, three consented to participate. Inclusion criteria were consenting adults aged 18 years or older who had chosen to self-administer psilocybin for chronic pain; no exclusion criteria were applied. The project received Institutional Review Board approval (UCSD IRB #800354) and participants were not compensated. Interviews covered five domains: history and severity of pain, prior management strategies, patterns of psilocybin use (dose and frequency), perceived benefits, and side effects. Pain intensity was assessed by participant self-report on the Numeric Rating Scale (NRS; 0=no pain to 10=worst pain imaginable). Cognitive and somatic side effects were self-reported. The authors defined a microdose operationally as an amount that does not produce an alteration of consciousness, generally 0.1–1 gram of dried mushrooms, acknowledging interindividual variation in metabolism and uncertainty in psilocybin concentration across mushroom sources. Formal medical records, diagnostic confirmation, or standardised psychiatric symptom scales were not obtained because participants were outside the UC San Diego health system.

Three case vignettes are presented, each describing sustained self-administered psilocybin use for chronic neuropathic pain. Patient DC: A 37-year-old man with cervical spinal cord injury and chronic lower-extremity neuropathic pain reported dramatic analgesia after experimenting with psilocybin. An initial full-psychedelic exposure (5 g dried mushroom powder) yielded near-total pain relief for 8–10 hours. He subsequently tried lower doses: 250 mg produced substantial analgesia for 6–8 hours along with muscle spasms he found therapeutic; 50 mg daily produced 90%–95% pain relief lasting 6–8 hours without spasms. He has used 50 mg almost daily for 6 months, discontinued tramadol, diazepam and cannabis, and denied rebound pain or withdrawal on missed days. He is quoted stating, "while those medications dulled the pain, the psilocybin totally mutes it, reducing my pain level from five to zero on average." Patient ES: A 69-year-old woman with progressive complex regional pain syndrome (CRPS) reported an initial 2 g dose that reduced pain to zero within an hour, with psychotropic effects lasting ~6 hours and analgesia for 18–20 hours. She then trialled microdosing: 500 mg provided ~80% pain relief for 3–4 hours without psychedelic effects, while 750–1000 mg produced 6–8 hours of complete relief but caused transient disorientation and gait instability during the first 3 hours. Her typical regimen is 500 mg daily for 7–10 days followed by 2–3 days off to avoid gastrointestinal side effects. She has microdosed for over a year without tolerance, rebound pain, or perceived loss of efficacy. Patient JP: A 40-year-old woman with radiculopathy after degenerative disc disease used 1000 mg of dried mushroom in a chocolate bar and experienced rapid reduction from baseline pain of 8/10 to 0/10 within an hour, accompanied by increased flexibility and relaxation. A single dose combined with home exercise produced analgesia that persisted for two weeks; pain gradually returned over 2–4 weeks and she spaces doses by 6–8 weeks. Repeated sessions produced cumulative benefit: a sustained shift in musculoskeletal baseline pain and apparent resolution of neuropathic radicular pain after the third session. She reported no notable somatic, cognitive, or behavioural side effects and continued a stable SSRI throughout. Across cases, the authors estimate psilocybin content using Psilocybe cubensis concentrations of roughly 0.5%–1% by mass, yielding approximate psilocybin doses of 1.25–2.5 mg (250 mg mushroom), 2.5–5 mg (500 mg), and 5–10 mg (1000 mg), while noting these are rough estimates. In two subjects analgesia lasted 3–8 hours and returned to baseline between administrations; in one subject analgesia persisted for weeks, suggesting possible mechanisms beyond acute 5-HT2A agonism. None of the three reported tolerance, withdrawal symptoms, or rebound pain with cessation. Side effects were generally minimal at microdoses, though higher, near-psychedelic doses produced transient psychotropic or functional impairment that limited regular use.

The investigators interpret these cases as preliminary evidence that sub-hallucinogenic doses of psilocybin may produce meaningful analgesia in diverse chronic neuropathic pain conditions, sometimes rivaluing relief from conventional analgesics and, in one case, enabling opioid discontinuation. They note that microdosing produced substantial pain reduction without the cognitive or perceptual impairments associated with higher, psychedelic doses, although higher doses tended to prolong analgesia at the cost of functional impairment. The authors situate their observations within a limited but growing literature on psychedelics and pain, emphasising that microdosing has been less studied than full-dose therapeutic protocols. They propose that the extended duration of analgesia in one participant may reflect downstream central modulation of nociception and synaptic plasticity rather than only acute 5-HT2A receptor activation. Synergy with adjunctive therapies is highlighted: one patient reported enhanced and longer-lasting benefit when psilocybin was combined with physical therapy, and the authors reference similar reports of synergy with mirror-visual feedback in phantom-limb pain. Key limitations acknowledged by the study team include the very small, self-selected sample; lack of generalisability; reliance on self-report without medical record verification; absence of formal pre/post psychiatric assessments that could clarify confounding effects of mood changes; variability and uncertainty in mushroom species and psilocybin content; and potential recall bias. The authors recommend controlled research to evaluate safety, tolerability, dosing, and efficacy of microdosed psilocybin for chronic pain and to investigate adjunctive treatment combinations that might enhance or prolong benefit.