Microdosing mushrooms in San Diego: what the research actually shows

Microdosing means taking psilocybin in amounts too small to cause a full psychedelic experience, usually again and again over weeks. Does it work? Surveys say people feel better. Placebo-controlled trials mostly find that people on a placebo improve about as much, and two depression trials reported in 2025 and 2026 didn't beat placebo at all. The fair summary: unproven, with real open questions.

What does microdosing actually mean?

There's no standard definition. In studies it usually means an amount below the level where people notice obvious perceptual changes, repeated over a period of weeks, but the amounts and patterns vary a lot from study to study and from person to person. That variation is one reason the research is hard to pin down.

The product is the other problem. Natural mushrooms vary in strength, and reviewers note that the active content of mushroom products can differ by more than tenfold.¹ Packaged "microdose" products are worse: the Diamond Shruumz bars and gummies recalled in 2024 were marketed for microdosing and were linked to 180 illnesses and 73 hospitalizations.² And when researchers tested 12 "magic mushroom" edibles bought in Portland shops, none contained psilocybin.³ Our page on smoke-shop mushroom gummies covers what's in them.

How many people microdose, and what UC San Diego has found

Interest has exploded, and some of the clearest measurements come from UC San Diego. A UC San Diego study in JAMA Health Forum, with psychiatry researcher Dr. Kevin Yang among its authors, found that online searches about microdosing rose about 1,250% from 2015 to 2023, as KPBS reported in 2024.⁴ In April 2026, Yang and colleagues at UC San Diego and NYU estimated from a national survey that about 2.8% of Americans, roughly 8 million people, used psilocybin in 2024. Adults 18 to 25 were 1.4 times as likely to have used it as people in their late 30s and 40s.⁵ That figure covers all psilocybin use, not just microdosing.

UC San Diego pain-medicine physicians also published a case series titled "Microdosing psilocybin for chronic pain" in the journal Pain in 2023.⁶ A case series describes individual patients without a comparison group, so it can raise a question worth testing but can't show that something works. For the university's controlled psilocybin studies, see psilocybin research in San Diego.

What surveys and observational studies found

The early evidence came from people who were already microdosing and agreed to report on it. Those studies are consistently positive and consistently hard to interpret.

• A study following 98 microdosers for six weeks found less depression and stress and less distractibility, but also more neuroticism. A second study by the same team found people expected bigger benefits than they reported, a sign of expectancy bias.⁷
• A web-based study of 81 people found improvements in well-being, anxiety and depression, but people's positive expectations at the start predicted how much they improved, which the authors called "suggestive of a significant placebo response."⁸
• App-based studies compared more than 4,000 microdosers with more than 4,600 non-microdosers, then followed 953 microdosers and 180 comparison participants for about a month. Microdosers reported better mood and mental health, with small to medium effects. These designs weren't blinded, and participants chose themselves.^9,10
• A 2020 systematic review called the overall picture "highly contradictory," with reports of both benefits and harms for mood, creativity and energy.¹¹

What placebo-controlled trials found

When neither the participants nor the researchers know who got the real thing, most of the benefit tends to show up on both sides.

• The self-blinding study (2021). 191 people who planned to microdose on their own used a self-blinding procedure, so they didn't know on a given day whether they'd taken their microdose or a placebo. Both groups improved on every psychological measure, with no significant difference between them, and the small differences seen on dosing days could be explained by people guessing what they'd taken. The authors concluded the anecdotal benefits "can be explained by the placebo effect."¹²
• A double-blind mushroom study (2022). In 34 people starting microdosing, effects beat placebo only among those who correctly guessed they'd had the real thing. There was no evidence of better well-being, creativity or thinking, and there were "few small changes towards cognitive impairment."¹³
• Crossover trials (2022). Psilocybin microdosing didn't change emotion processing, anxiety or depression compared with placebo.¹⁴ A companion study found more awe in response to some videos, but about two-thirds of participants figured out which condition they were in.¹⁵
• A home-dosing LSD trial (2023). LSD trials matter here because they're among the best-controlled microdosing data. In 80 healthy men over six weeks, people felt brief boosts in mood, energy and creativity on dosing days, but no lasting change survived statistical correction. Feeling jittery was far more common on LSD (32.5% vs 7.5%), and four people dropped out because of anxiety.¹⁶ Participants felt more creative, but objective creativity tests showed no difference.¹⁷

The newest results, 2025 and 2026

Trials have moved from healthy volunteers toward people with depression. So far the results haven't favored microdosing.

• LSD microdosing for depression. MindBio's phase 2B trial randomized 89 people to LSD microdoses or an active placebo. Both groups improved, and placebo improved more: depression scores fell about 36% on placebo versus about 30% on LSD. The company concluded microdosed LSD wasn't effective for major depression. The results were announced in a November 2025 press release.¹⁸
• Psilocybin microdosing for depression. In a phase 2 trial of 39 adults, depression scores fell about the same amount on psilocybin and on placebo after four weeks, with no serious adverse events. The authors noted that taking part in the trial itself brought meaningful improvement. This one hasn't been peer-reviewed yet.¹⁹
• Psilocybin truffle trials. Two double-blind trials found microdosing "did not significantly affect behavioral or subjective measures compared to placebo," while unpleasant bodily feelings were more common on the active dose.²⁰ Pooling three such trials (171 people) turned up only a small effect on one measure of original thinking.²¹
• The 2026 meta-analysis. A review of 24 studies and 3,681 healthy adults in CNS Drugs found that in randomized trials microdosing produced noticeable subjective and brain-wave effects but "minimal impact on cognition, creativity, or sustained mood," and "no clear evidence" of reduced depression, anxiety or stress versus placebo. Improvements in observational studies were "likely influenced by expectancy or lifestyle factors."²²

So is microdosing just a placebo?

Not quite, according to some researchers. A 2024 review of 19 placebo-controlled studies found genuine drug-versus-placebo differences in brain activity, physiology, how people felt, mood and thinking, and argued it's "not yet possible to determine whether microdosing is a placebo," given small samples, short studies and mostly healthy participants.²³ Researchers behind the self-blinding study describe it another way: a real but noticeable drug effect can tip people off about what they took, which then activates their expectations, an "active placebo."²⁴

For a reader, that adds up to three points:

• The effects people feel on a dosing day can be real.
• Lasting improvements in mood, focus or creativity beyond what placebo produces haven't been shown, including in the two depression trials completed so far.
• Expectations are powerful. Many people in these trials got better whether or not they received the drug.

What are the risks of repeated use?

Heart valves, in theory. Some drugs that damaged heart valves, such as fenfluramine (the "fen" in fen-phen), act on the serotonin 5-HT2B receptor, and psilocin binds that receptor strongly. A 2023 review found psilocin had the narrowest estimated safety margin of the psychedelics it examined and called valve disease "a potential risk with chronic psychedelic microdosing." No case in a microdoser has been documented, and the authors called for trials of at least six months with heart scans.²⁵ A 2024 analysis called the risk "uncertain at this point."²⁶ A 2026 study of about 287,000 adults found a small association between lifetime use of any hallucinogen and valve disease that its authors called exploratory.²⁷ A 2026 review sums it up: biologically plausible, not established.¹

Interactions. Repeated use means repeated overlap with any medication you take. Lithium carries a serious seizure warning in online reports, and SSRIs and SNRIs often blunt the effect.^28,29 Never stop a prescription on your own. The full table is on our psilocybin safety page.

Anxiety and jitteriness. Even at small doses, trials report anxiety, jitteriness and unpleasant bodily feelings, and some participants quit because of them.^16,20

Not knowing what you're taking. Packaged "microdose" products have contained synthetic drugs, kava compounds and prescription drugs instead of, or alongside, psilocybin.^2,3

Is microdosing legal in California?

No. A microdose is still possession of psilocybin, a controlled substance under California law and a Schedule I drug federally. California's simple-possession statute, Health and Safety Code section 11377, doesn't make an exception for small amounts. Possession is a misdemeanor punishable by up to a year in county jail, except for people with certain serious prior convictions.³⁰ No city in San Diego County has adopted a measure deprioritizing psilocybin enforcement, as far as published trackers show; the California cities that have are all in the northern half of the state.³¹ The 2024 Prop 36 "treatment-mandated felony" expressly excludes psilocybin.³² The full picture is in are mushrooms legal in San Diego? This is general information, not legal advice.

If you're considering it

We won't tell anyone how to microdose. We will say what the evidence supports:

• Talk to a clinician first, especially if you take lithium, an antidepressant, an antipsychotic or a medication that affects seizures, or if you have a heart condition or a personal or family history of psychosis or bipolar disorder.
• If you're struggling with depression or thoughts of suicide, don't make microdosing the plan. Call or text 988, or the San Diego Access & Crisis Line at 888-724-7240, and see a professional. Treatments with stronger evidence exist.
• Legal options exist. Clinical trials and licensed programs in other states are the only legal routes to psilocybin; see psychedelic therapy options for San Diegans.