A single 20-microgram dose of LSD eased experimentally induced pain in healthy adults, while lower doses did not
A 2020 controlled lab study tested whether single low doses of LSD could dull pain in 24 healthy adults, using a cold-water pain task.
For decades, some people with severe pain have reported that LSD dulls it, but almost no modern research had tested the idea. In this study, 24 healthy adults each took a single low dose of LSD — 5, 10, or 20 micrograms — and a dummy dose on four separate days, without knowing which they had received. Pain was measured by how long they could hold a hand in near-freezing water. Only the largest dose, 20 micrograms, made a difference: people tolerated the cold about 20% longer and rated it as less painful and less unpleasant. The two smaller doses did nothing. The drug effects people felt were mild, and blood pressure rose only slightly. These were healthy volunteers, not people living with ongoing pain.
In this randomized, double-blind, placebo-controlled, within-subject (crossover) dose-response study, 24 healthy adults (12 male, 12 female; mean age 22.7) each received single oral doses of 5, 10, and 20 μg LSD and placebo on four separate test days, with at least a 5-day washout between sessions. Pain was assessed with a Cold Pressor Test — time tolerating a hand in 3°C water, plus subjective painfulness and unpleasantness ratings — at 1.5 and 5 hours after dosing. Analysis of variance showed a significant main effect of treatment on pain tolerance (F(3,157) = 5.3, p = 0.002). In LSD-placebo contrasts, only the 20 μg dose significantly increased pain tolerance (p = 0.006) — by about 20% — and decreased painfulness (p = 0.012) and unpleasantness (p = 0.008); the 5 and 10 μg doses did not. The effect was equal at 1.5 and 5 hours. LSD raised mean blood pressure by less than 10 mmHg (within the normal range) and slightly increased dissociation, anxiety, and somatization.
The authors frame this as the first modern revisit of LSD as an analgesic and call for the findings to be replicated in patient populations with persistent pain and comorbid neuropsychiatric conditions, and for the potential for tolerance after repeated dosing to be determined. They note the analgesic effect may outlast the 5-hour window they measured, and that an extended dose-finding study is needed because only the top dose worked, leaving the optimal dose unknown. Design-inherent points, in plain terms: the sample was small; participants were healthy volunteers experiencing brief, experimentally induced cold-water pain, not real-world clinical pain, which limits generalizability to pain patients; each dose was administered only once; and the study was funded by a private foundation (the Beckley Foundation) rather than independent public funding, though the authors declared no conflicts of interest. The crossover design, in which each person served as their own comparison, strengthens the within-subject dose contrast.
Twenty-four healthy volunteers received single doses of 5, 10 and 20 µg LSD as well as placebo on separate occasions, and LSD 20 µg significantly increased the time that participants were able to tolerate exposure to cold water and decreased their subjective levels of experienced pain and unpleasantness (Ramaekers et al., 2020, Journal of Psychopharmacology).
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