Psilocybin and SSRIs: what the research says

If you take an SSRI or SNRI antidepressant, you may have wondered what happens if psilocybin is added. This page sets out what the research shows, and where it runs out.

The short version

• One controlled study specifically tested how escitalopram changes psilocybin's effects, in 23 healthy volunteers. A second, open-label trial gave psilocybin to 19 people with depression who stayed on their SSRI. Neither found a serious interaction. Both were small and short ^{[1] [2]}.
• No controlled study has reported serotonin syndrome from psilocybin and an SSRI ^{[1] [8]}. Three reviews describe the evidence on these interactions as limited, and the 2025 interaction review says much of it comes from case reports ^{[6] [7] [8]}.
• Several surveys report a weaker psilocybin experience in people on these antidepressants, but not every study found it ^{[1] [3] [4] [8]}.
• Studies comparing people who tapered off an antidepressant before a psilocybin trial with people who were not on one disagree ^{[10] [11] [12]}.
• Reported concerns with specific combinations include seizures with lithium, and serotonin toxicity with an MAOI taken alongside an SSRI ^{[7] [14]}.
• Psilocybin is a Schedule I drug under federal law and Montana law ^{[19] [20]}.

What the studies found

One controlled study found no serious interaction. Researchers in Basel, Switzerland gave healthy volunteers psilocybin after two weeks of escitalopram (Lexapro) or a placebo. Twenty-three people completed the study. Escitalopram had no relevant effect on the positive mood effects of psilocybin, and it reduced bad drug effects, anxiety and cardiovascular side effects. It did not change how the body processed psilocin, the active form of psilocybin. The volunteers were healthy, took escitalopram for only two weeks, and were not being treated for depression. The authors note the findings may not apply to other antidepressants or to longer treatment ^[1].

Depression scores improved in a small trial without a comparison group. Nineteen people with treatment-resistant depression stayed on their SSRI and received a single dose of synthetic psilocybin with psychological support. Their depression scores fell by an average of 14.9 points on the MADRS scale after three weeks. Eight of the 19 (42%) had scores at least 50% lower than at the start, and low enough to meet the study's definition of remission. There were no serious adverse events, and the most common complaint was headache. Twelve participants had at least one adverse event during the study, including two with an event rated severe. With no comparison group, the trial cannot show how much of the improvement came from psilocybin ^[2].

Many people report a weaker experience. A Johns Hopkins survey collected 611 reports of taking psilocybin mushrooms while on an antidepressant. Weaker than expected effects showed up in 47% of reports on an SSRI and 55% on an SNRI, compared with 29% on bupropion, which works differently. After people stopped an SSRI or SNRI, reports of weaker effects did not drop off significantly over the following months, and the authors conclude the dampening may last as long as three months. This was a look-back survey of self-reports, not a trial ^[3].

A 2024 survey followed 161 people with a psychiatric condition forward in time. It covered several classic psychedelics, mostly psilocybin. The 63 on an SSRI or SNRI reported less intense effects, while both groups reported similar improvements in well-being and depression symptoms afterward. These were exploratory analyses, medication use was not verified, and the study did not report side effects ^[4]. An analysis of 443 Reddit posts about SSRIs and mushrooms found that 54% described a weaker experience and 39% described no change. These were anonymous, unverified accounts ^[5]. The 2025 interaction review notes that weaker effects were not seen in every study ^[8].

The reviews agree the evidence is limited. A 2022 review of interactions between psychiatric medications and psilocybin or MDMA included 40 publications, and found only one randomized trial combining psilocybin with an SSRI ^[6]. A 2024 review across all classic psychedelics found 52 studies, ten of them on psilocybin, and no serious adverse drug events outside a few case reports ^[7]. A 2025 review concluded that taking antidepressants and psilocybin together was generally safe and tolerable, with no increased risk of serotonin syndrome. It also stressed that the evidence comes mostly from case reports and that controlled trials are lacking ^[8]. That conclusion is the authors' own reading, not a safety guarantee.

What the research does not show

• It does not show the combination is proven safe. One small controlled study and one small open-label trial, 42 people between them, cannot rule out rare problems ^{[1] [2]}. Most psilocybin trials have asked people to stop antidepressants first, which is one reason so little data exists ^[2].
• It does not settle whether stopping an antidepressant helps or hurts. Three secondary analyses compared people who stopped medication before a psilocybin trial with people who entered without medication. None was a randomized test of stopping versus staying on a medication, so they cannot show that stopping caused any difference ^{[10] [11] [12]}. In one, the 11 participants in the psilocybin group who had stopped an SSRI or SNRI showed less improvement than those who entered unmedicated, and the authors called for a proper trial ^[10]. The largest used data from 233 participants and found no link between stopping and worsening depression or a weaker treatment effect. All of its authors were employees and shareholders of the sponsoring company, Compass Pathways ^[11]. An exploratory analysis of 27 participants found no statistically significant differences between the groups ^[12]. One case report describes a man taking duloxetine and vortioxetine who stopped duloxetine before a second psilocybin session. He developed dizziness, muscle pain and fatigue, and his depression scores worsened after that session ^[13]. Stopping an antidepressant can bring withdrawal symptoms or a relapse ^[6]. It is a decision to make with your prescriber.
• It does not cover microdosing. A 2026 review of low-dose psilocybin found no study testing a microdosing regimen in people taking SSRIs ^[24]. One 2024 case report of serotonin toxicity involved microdosing alongside three antidepressants ^[9].
• It does not treat mushrooms and pure psilocybin as the same thing. The controlled study and the open-label trial used measured psilocybin in supervised settings ^{[1] [2]}. The surveys describe people's own mushroom use ^{[3] [5]}. In one case involving mushrooms, an MAOI and an amphetamine, the authors suggested that another compound in the mushrooms may have caused a blood pressure emergency ^[17].

Reported concerns with specific combinations

Lithium. An analysis of 62 online reports involving lithium and a classic psychedelic found that 47% described a seizure and 18% a bad trip. None of 34 reports involving lamotrigine, another mood stabilizer, described a seizure. For lithium and psilocybin specifically, two of six reports described a seizure. The authors call these reports low quality evidence, because they are unverified, and they still conclude that lithium should be considered a contraindication to psychedelic use ^[14]. A 2024 review suggested that classic psychedelics alone may not raise seizure risk in healthy people, while combining them with substances such as lithium could. The authors cautioned that the findings may not apply beyond the people and settings studied ^[15].

MAOIs. Monoamine oxidase inhibitors are an older class of antidepressant, and the plant brew ayahuasca also contains them. The 2024 review advises caution with MAOI-containing preparations taken alongside SSRIs or SNRIs, because of concern about serotonin toxicity. The serotonin toxicity reports it discusses with an SSRI involved fluoxetine (Prozac) taken with an MAOI plant preparation ^[7]. Serotonin syndrome is a potentially life-threatening reaction to too much serotonin activity. Its signs include agitation or confusion, a rapid heart rate, sweating, tremor, muscle twitching and overactive reflexes, with high fever and muscle rigidity in severe cases. Some MAOIs are strongly associated with severe cases, especially in combination with SSRIs and certain other drugs ^[16]. Separately, a 2024 case report describes a blood pressure emergency in a man who took psilocybin mushrooms while on an MAOI and an amphetamine. He recovered ^[17].

SSRIs and SNRIs. Several surveys report weaker effects, the one small controlled study found no serotonin toxicity, and the evidence overall is limited ^{[1] [3] [4] [8]}.

When to get help

Call 911 for a very high temperature, severe muscle stiffness, a racing heart with marked confusion or agitation, or a seizure ^{[14] [16]}.

Talk with your prescriber before any change to a psychiatric medication, and tell them honestly what you are considering.

For support during or after a hard experience, the Fireside Project runs a free, confidential peer support line. Call or text 62-FIRESIDE (623-473-7433), any day from 11 a.m. to 11 p.m. Pacific, which is noon to midnight in Montana. It is emotional support, not medical care, and it is not a suicide hotline. In a crisis, call or text 988 ^[23].

In 2008, Johns Hopkins researchers published safety recommendations for psilocybin research and described their own screening. They excluded people with certain psychiatric histories, including psychosis or bipolar disorder in the person or a first- or second-degree relative, people on certain medications, and people whose resting blood pressure was above 140/90. They recommended at least two trained monitors during a session ^[18].

Where the law stands

Psilocybin and psilocin are Schedule I controlled substances under federal law and under Montana law, which lists them by name ^{[19] [20]}.

In April 2026, Compass Pathways reported that the FDA had agreed to review its synthetic psilocybin for treatment-resistant depression on a rolling basis, and had awarded it a priority voucher meant to shorten the review ^[21]. In August, the company said it expected to finish its application by the end of 2026, with a possible launch in the first half of 2027, if the FDA approves it and the DEA reschedules psilocybin ^[22].

Common questions

Can I take psilocybin on Lexapro?

Lexapro is escitalopram. In the one controlled study, healthy volunteers who took escitalopram for two weeks had no serious interaction with psilocybin and fewer bad effects ^[1]. That study was small and short, and it is not a safety guarantee. Ask your prescriber.

Do I have to stop my SSRI first?

Most psilocybin trials have required it ^[2]. Studies comparing people who tapered off with people who were not on medication disagree ^{[10] [11] [12]}. In one survey, weaker effects were still reported for up to about three months after stopping ^[3]. Stopping an antidepressant can bring withdrawal symptoms or a relapse ^[6], and it is a decision to make with your prescriber.

Can an SSRI and mushrooms cause serotonin syndrome?

The risk is not established. The small controlled study of psilocybin with escitalopram found no serotonin toxicity, but it did not test mushrooms ^[1]. In the Johns Hopkins survey, 2.8% of people believed they had developed serotonin syndrome, but none of those cases could be confirmed ^[3]. In the Reddit study, 13 posts described symptoms that may reflect serotonin toxicity. These were not verified diagnoses ^[5]. One published case met the formal criteria: a woman on an SNRI and bupropion who was microdosing mushrooms developed it two days after trazodone was added. The authors say psilocybin's part in it is not fully known ^[9]. The 2024 review also discusses serotonin toxicity reports involving fluoxetine taken with MAOI plant preparations ^[7].