Ayahuasca: What It Does, Why People Fly to Thailand for It, and the Real Risks

Most of the patients I see who have used ayahuasca did not go to Peru. They attended a ceremony somewhere in the hills of Chiang Mai or a retreat in the south of Thailand, run by someone with varying degrees of preparation. They arrive at our clinic weeks or months later, still managing intrusive visuals, sleep disruption, or anxiety that won’t settle. The experience itself often felt meaningful to them. That doesn’t mean it was without consequence.

What ayahuasca actually is and what is in it

Ayahuasca is a psychedelic brew made from two Amazonian plants: the Banisteriopsis caapi vine and the leaves of Psychotria viridis. It originates from indigenous communities in Peru, Brazil, Colombia, and Ecuador, where it has been used for centuries in healing ceremonies led by a trained shaman.

The active psychedelic compound is DMT, short for N,N-dimethyltryptamine. DMT is found in the Psychotria viridis leaves. On its own, DMT is broken down almost immediately by monoamine oxidase enzymes in your gut and liver before it can reach your brain in meaningful amounts. That is where the vine comes in. Banisteriopsis caapi contains beta-carboline alkaloids, primarily harmine, harmaline, and tetrahydroharmine, which are potent monoamine oxidase inhibitors. They block those enzymes long enough for DMT to survive digestion and cross into the bloodstream.

The result is a psychedelic experience that lasts far longer than smoked DMT, which clears in under 30 minutes. Oral ayahuasca keeps you in an altered state for 4 to 6 hours, sometimes longer.

How ayahuasca works in the brain

DMT’s primary mechanism is agonism at the 5-HT2A receptor, which is the same serotonin receptor that psilocybin and LSD target. Activating 5-HT2A in the prefrontal cortex disrupts the brain’s default mode network, the neural system responsible for your normal sense of self and predictive processing of reality. That disruption is what produces ego dissolution, visual hallucinations, and altered time perception.

DMT also binds to sigma-1 receptors, which are involved in neuroplasticity and stress response, and has weak activity at dopamine receptors. The beta-carboline MAO inhibitors add their own pharmacological layer: harmine itself has mild antidepressant properties by increasing serotonin availability, similar to how pharmaceutical MAO inhibitors work.

Ayahuasca effects: what happens physically

The physical effects begin within 20 to 60 minutes of drinking the brew. Nausea and vomiting are nearly universal. In traditional ceremony, vomiting is referred to as “la purga,” the purge, and is considered spiritually significant. Clinically, it is a direct consequence of peripheral serotonin receptor activation in the gut combined with the MAO inhibitor activity.

Beyond purging, the physical profile of ayahuasca includes a sustained rise in heart rate and blood pressure, pupil dilation, increased body temperature, salivation, and sweating. In the Global Ayahuasca Survey of over 10,000 users, around 70% reported physical side effects during the experience, with nausea and vomiting the most common. Chest discomfort, difficulty breathing, and brief loss of consciousness were reported in a minority but are clinically significant, particularly in anyone with pre-existing cardiac conditions.

Ayahuasca effects: what happens psychologically

The psychological experience is intense and highly variable. Most users report vivid visual hallucinations: geometric patterns, entities, symbolic narratives. Auditory hallucinations are common. Many people describe a profound sense of reviewing their own life, confronting suppressed memories, or experiencing something they interpret as spiritual contact.

Emotionally, ayahuasca tends to amplify whatever is already present. If you carry unresolved trauma, grief, or significant anxiety, the experience will not suppress those. It surfaces them, often forcefully. This is why proponents argue for its therapeutic potential, and why it can go badly wrong without preparation and support.

Around 56% of Global Ayahuasca Survey respondents reported some negative mental health impact in the days and weeks after use. The most common were prolonged dissociation, paranoia, disturbing intrusive thoughts, depressed mood, and seeing or hearing things that others do not, persisting after the acute experience had ended.

Hallucinogen persisting perception disorder after ayahuasca

Hallucinogen persisting perception disorder, known as HPPD, is a condition where visual disturbances from a hallucinogenic experience do not fully resolve. Patients describe visual snow, trailing afterimages, geometric overlays on real environments, and halos around objects. HPPD can persist for months or years. There is no reliable pharmacological treatment. The condition is rare but real, and I see it more often in people who used ayahuasca without adequate preparation, used it repeatedly in short succession, or had pre-existing anxiety or depersonalisation.

For a comparison of how different hallucinogens produce lasting neurological changes, the clinical picture has some overlap with what we see after heavy LSD use, which we discuss in detail when covering the long-term effects of LSD.

Ayahuasca-induced psychosis

Psychedelic-induced psychosis is rare in otherwise healthy people without a personal or family history of psychotic disorders. However, ayahuasca’s combination of intense 5-HT2A agonism and extended duration makes it more likely to precipitate a psychotic episode than shorter-acting psychedelics, particularly in individuals with underlying vulnerability. Schizophrenia spectrum disorders and bipolar disorder type 1 are absolute contraindications to ayahuasca use from a clinical standpoint.

Ayahuasca effects duration: how long does it last

The acute experience runs 4 to 6 hours in most cases. The peak, where hallucinations and emotional intensity are highest, usually occurs between 60 and 90 minutes after ingestion and lasts 1 to 2 hours. The come-down is gradual, with residual perceptual changes and emotional sensitivity often persisting for several hours after the peak.

The following day, many users describe a heightened emotional openness sometimes called the “afterglow.” For others, particularly those who had a difficult experience, the aftermath involves anxiety, disturbed sleep, and difficulty distinguishing what they encountered during the ceremony from their current reality.

Ayahuasca in Thailand: what you need to know legally and practically

Thailand classifies DMT as a Schedule 1 narcotic under the Narcotics Act B.E. 2522. This is not a grey area. Possession, production, import, and distribution of DMT, which includes ayahuasca as a DMT-containing preparation, carry severe criminal penalties, including imprisonment.

Despite this, ayahuasca ceremonies operate covertly across Thailand, particularly in tourist areas around Chiang Mai, Pai, Koh Phangan, and Phuket. They are advertised through private networks, wellness retreat networks, and social media. Some are run by experienced practitioners; many are not. The clinical risk in poorly supervised settings is substantial.

The pattern we see in clinic is that people attend a ceremony seeking healing, particularly for depression, PTSD, or trauma, without disclosing psychiatric history or current medications to the facilitator. The interaction risks are severe. No one in an unregulated ceremony setting has the clinical tools to manage serotonin syndrome, a cardiac event, or acute psychosis.

Potential therapeutic uses of ayahuasca: what the research actually shows

There is genuine scientific interest in ayahuasca’s therapeutic potential. The most robust evidence so far is in treatment-resistant depression. A 2019 randomised controlled trial published in Psychological Medicine found a single ayahuasca dose produced rapid and significant antidepressant effects compared to placebo in patients with treatment-resistant depression. The proposed mechanism involves 5-HT2A-mediated increases in brain-derived neurotrophic factor (BDNF), which supports neuroplasticity, combined with the psychological effect of confronting difficult emotional material in a structured way.

Research is also ongoing in PTSD, addiction, and end-of-life anxiety. The WHO has noted growing scientific interest in psychedelic-assisted therapies, though none have yet received regulatory approval as a clinical intervention.

What the evidence does not support is the idea that attending an uncontrolled ceremony in a foreign country with no clinical oversight replicates the safety conditions of a clinical trial. In research settings, participants are screened extensively, they are not on serotonergic medications, and trained clinicians are present throughout. Those conditions do not exist in a jungle retreat.

Who should not use ayahuasca

The contraindications to ayahuasca use are not suggestions. They are based on documented mechanisms that can cause serious harm.

Anyone taking SSRIs, SNRIs, MAO inhibitors, tricyclic antidepressants, tramadol, linezolid, or lithium should not use ayahuasca. The serotonin syndrome risk is not theoretical. Anyone with a personal or family history of schizophrenia, schizoaffective disorder, or bipolar type 1 should not use ayahuasca. Anyone with a cardiovascular condition, uncontrolled hypertension, or a history of seizures is at elevated physical risk. Pregnancy is an absolute contraindication.

The short-term drug effects profile of ayahuasca overlaps with other powerful serotonergic substances. If you want to understand how serotonergic and stimulant mechanisms interact more broadly, our overview of the short-term effects of drugs covers the pharmacological framework.

Is ayahuasca addictive

Ayahuasca does not produce physical dependence in the way opioids or alcohol do. There is no withdrawal syndrome. The 5-HT2A receptor downregulates rapidly with repeated stimulation, meaning tolerance to the hallucinogenic effects develops within days. This pharmacological tolerance is one reason people rarely use it daily.

That said, psychological dependence is a documented clinical reality. Some individuals use ayahuasca repeatedly to manage emotional pain, trauma, or depressive episodes, essentially using the ceremony as a coping mechanism rather than seeking underlying treatment. This pattern can delay appropriate psychiatric care by months or years. The self-medicating function is the same regardless of the substance being used, and the psychological effects of drug abuse follow predictable patterns even when the drug itself is not conventionally addictive.

Most people who use ayahuasca do so once or a handful of times. But when someone is attending ceremonies every few weeks, or using the experience to manage depression, anxiety, or trauma without engaging any other form of treatment, that is a clinical pattern worth examining. The DSM-5 framework for substance use disorders focuses on loss of control, continued use despite consequences, and interference with functioning. Ayahuasca use can meet those criteria even without physical dependence.

At Phuket Island Rehab, we work with people managing the aftermath of difficult psychedelic experiences, persistent HPPD, psychosis triggered by ceremonial use, and patterns of psychological reliance on altered states to avoid working through underlying mental health conditions. Our clinical team can assess what is happening, stabilise the acute picture, and build a treatment plan that actually addresses the underlying drivers.

Ayahuasca produces its effects through a combination of DMT, a potent 5-HT2A receptor agonist, and beta-carboline MAO inhibitors that allow DMT to reach the brain orally. The acute experience lasts 4 to 6 hours and involves visual hallucinations, emotional intensity, autonomic arousal, and near-universal nausea and vomiting. The psychological aftermath is variable: some people report meaningful benefit, while a significant minority experience prolonged dissociation, anxiety, intrusive thoughts, or HPPD that persists for weeks or months. The most serious acute risks are serotonin syndrome from medication interactions, cardiovascular events, and psychosis in vulnerable individuals. In Thailand, DMT is a Schedule 1 controlled substance, and unregulated ceremonies present both legal and medical risks without the clinical safeguards present in research settings.

From a practical standpoint, if you are considering ayahuasca for a legitimate mental health concern, the most important steps are full disclosure to a psychiatrist before making any decision, a thorough medication review, and screening for personal and family psychiatric history. If you or someone close to you has already had an experience that did not resolve cleanly, including persistent visual changes, paranoia, disturbed sleep, or emotional dysregulation weeks after the ceremony, those symptoms warrant clinical assessment, not waiting it out. As John A. Smith of Phuket Island Rehab puts it: “The patients who struggle most aren’t the ones who had a difficult ceremony. They’re the ones who were told the difficulty would pass on its own, waited six months to tell anyone, and by then had built their whole avoidance structure around not talking about it.”

How long do ayahuasca effects last?

The acute effects of ayahuasca last 4 to 6 hours in most cases, with the peak occurring around 60 to 90 minutes after ingestion. Physical effects like nausea tend to resolve within the first 2 to 3 hours, while emotional sensitivity and altered perception can persist through the full 6-hour window. Some people experience lingering effects, including vivid dreams, mood shifts, and altered perception, for several days afterward.

Is ayahuasca legal in Thailand?

No. DMT is classified as a Schedule 1 narcotic under Thailand’s Narcotics Act, and ayahuasca contains DMT as its primary psychoactive compound. Possession, use, and distribution carry serious criminal penalties. Covert ceremonies do operate in tourist areas across Thailand, but participants face real legal risk alongside the medical risks.

Can ayahuasca cause lasting psychological damage?

Yes, in some individuals. Hallucinogen persisting perception disorder, prolonged dissociation, and psychosis are documented consequences of ayahuasca use, particularly in people with pre-existing vulnerability, psychiatric history, or who use it repeatedly. The Global Ayahuasca Survey found that 56% of respondents experienced some negative mental health impact in the weeks following use, and a subset required professional mental health support.

What medications interact dangerously with ayahuasca?

The most dangerous interactions are with serotonergic medications, because ayahuasca’s beta-carboline components are MAO inhibitors, and combining MAOIs with serotonergic drugs can cause serotonin syndrome, a potentially fatal condition. This includes SSRIs such as fluoxetine and sertraline, SNRIs such as venlafaxine, tricyclic antidepressants, tramadol, lithium, and linezolid. Anyone on these medications must not use ayahuasca, and the washout period for some SSRIs can extend to several weeks.

Is ayahuasca addictive?

Ayahuasca does not cause physical dependence or withdrawal, but psychological dependence is clinically real. Rapid 5-HT2A receptor tolerance limits daily use pharmacologically, but some people develop a pattern of using ceremonies as their primary coping mechanism for depression, trauma, or anxiety, which constitutes a problematic pattern even without physical addiction. This delay in seeking appropriate psychiatric treatment is the main clinical concern with repeated recreational or self-therapeutic use.

What is the difference between ayahuasca and psilocybin mushrooms?

Both ayahuasca and psilocybin act primarily at the 5-HT2A serotonin receptor, but they differ in duration, intensity, and pharmacological complexity. Psilocybin effects last 4 to 6 hours with less autonomic stimulation and virtually no interaction risk with other medications at standard doses. Ayahuasca lasts a similar duration but involves the additional pharmacological layer of MAO inhibition, making drug interactions far more dangerous and the physical side effect burden significantly higher. The mushroom gummies effects profile gives a useful point of comparison for 5-HT2A-mediated hallucinogenic experiences.

What should I do if someone is having a crisis during an ayahuasca ceremony in Thailand?

Call 1669, Thailand’s emergency medical number, immediately if someone is unconscious, has a very fast or irregular heartbeat, is severely agitated or confused, has muscle stiffness, or is having a seizure. Tell emergency responders exactly what substance was taken and when. Do not attempt to restrain someone experiencing panic or paranoia. If the person is conscious and distressed but medically stable, move them to a quiet space, reduce sensory input, and stay with them calmly until the acute phase passes. Seek professional follow-up regardless.