LSD

What is LSD?

Lysergic acid diethylamide, usually called LSD or acid, is a synthetic classic psychedelic. It can substantially change perception, emotion and the sense of time and self.

Its effects overlap with those of psilocybin, though LSD generally lasts longer. That longer duration is an important part of preparation.

Holze et al. (2022): direct comparison of LSD and psilocybin · Holze et al. (2022): controlled comparison of psilocybin and LSD

What might it feel like?

At the beginning, you may notice a heightening of colour and sound, a stream of thoughts, and laughter starting to emerge. Familiar surroundings can become absorbing. You might feel excited, physically restless or unsure as the changes build.

Music, images and thoughts

As the music plays, you may find yourself drifting into thoughts and the visual field, much like moving into and out of a dream. Shapes and patterns may expand and contract. Music can seem to have texture, colour or movement, with changes in the music bringing changes in how you feel.

One thought may open into another. You may see a familiar relationship or personal concern from a different perspective, or become absorbed in something ordinarily easy to overlook. At other times, thoughts repeat and it can be difficult to shift your attention.

Connection and a changing sense of self

Journeyers describe moments when the usual separation between themselves and the world becomes less distinct. There can be a deeply felt unity, tremendous joy or love, and a recognition of beauty that is hard to explain afterward. Memories, sadness, fear and confusion can also be part of the experience.

LSD gives these changes a long stretch of time to unfold. You may move between deep absorption and periods when your surroundings feel more familiar. Having someone you trust available throughout the day can help you feel supported.

In someone’s own words

“I think that the music was kind of the sea in which I was traveling through with my vessel”

Participant 20, Hendricks et al. (2022)

If you feel overwhelmed, tell your sitter. A familiar voice, quieter music or feeling your feet on the floor may help you settle. You can ask for reassurance or a change in the surroundings.

When might effects begin?

Effects commonly begin gradually within about 30–60 minutes. The timing can vary. A slow or subtle start is not a reason to take more.

Holze et al. (2022): controlled comparison of psilocybin and LSD

When might it feel strongest?

In a controlled study, the strongest effects occurred around two to three hours after administration on average. There was variation between participants, and intensity can change throughout the experience.

Holze et al. (2022): controlled comparison of psilocybin and LSD

How long might it last?

In a controlled comparison, LSD’s effects lasted about nine to eleven hours on average, with some experiences considerably longer. Arrange support for the whole day and allow time to rest afterward. Avoid driving or other responsibilities while you remain affected or sleep-deprived.

Holze et al. (2022): controlled comparison of psilocybin and LSD

Coming down and the days afterward

As the experience eases, familiar surroundings may return with a feeling of warmth, peace or appreciation. You may want to talk, move gently with music or sit quietly. Some journeyers feel emotionally raw or tired, and sleep may still be difficult. Keep the rest of the day simple, with support available.

Some journeyers describe an afterglow of openness, connection or positive mood. Others need more time to feel settled. Persistent or worsening anxiety, unusual perceptions, mood changes or disrupted sleep deserve assessment.

Holze et al. (2022): controlled comparison of psilocybin and LSD · Evens et al. (2023): systematic review of the psychedelic afterglow

Use the Integration Guidebook at your own pace.

Write down what feels meaningful if you want to, and give yourself time before making major decisions. If a memory emerges, explore it gently without pressure from anyone to decide exactly what happened.

Potency: why a tab is not a standard amount

The amount of LSD on a tab can vary. A printed design, seller’s estimate or previous tab does not establish how much LSD is present—or whether the substance is LSD.

The quantities used in a trial are selected for that study and its participants. They cannot determine what is appropriate for someone else. Never take more to overcome suspected medication-related blunting.

Chemical analysis of seized blotters (2016) · Holze et al. (2022): direct comparison of LSD and psilocybin

What to know about the product

LSD is often sold on blotter paper or in liquid form. Appearance cannot establish identity, strength or purity. Other substances may be sold as LSD and have different risks. Drug checking has limits and does not establish that a product or experience is safe.

Chemical analysis of seized blotters (2016)

Medications and LSD

A controlled study in 23 healthy adults found that LSD after six weeks of paroxetine preserved pleasant effects and reduced some unpleasant effects, while increasing LSD blood exposure. The findings apply to this combination under monitoring. Other SSRIs and treatment outcomes in people with depression need further study. Becker et al., 2025 — LSD and paroxetine trial.

Do not abruptly stop an SSRI or another psychiatric medication to prepare for a psychedelic experience. Taking an antidepressant does not automatically mean you need to taper. Continuing, changing or tapering a medication is an individual decision with the prescribing clinician, taking into account the particular medication, psychedelic and your current health. Never increase a psychedelic dose to overcome suspected medication-related blunting. Read Medication considerations for the substance-specific evidence and questions to bring to your prescriber.

Risks and when to get help

Nausea, headache, anxiety and changes in blood pressure can occur. Confusion or impaired judgement can create danger even when physical symptoms seem mild. Some people experience prolonged distress or recurring visual disturbances. Selected clinical studies cannot establish safety for everyone.

Bipolar disorder, psychosis vulnerability, unstable mental health and important cardiovascular conditions need particular caution. Lithium raises a serious concern about seizures with classic psychedelics; do not stop lithium to make room for a psychedelic. Review this and other combinations in Medication considerations.

Call emergency services for seizures, collapse, breathing difficulty, chest pain, severe overheating, or confusion with marked stiffness or repeated jerking. Do not assume concerning symptoms are simply part of the experience.

Hinkle et al. (2024): systematic review of adverse events · Johnson et al. (2008): human psychedelic research safety guidelines

Holze et al. (2022): controlled comparison of psilocybin and LSD

Nayak et al. (2021): lithium and seizure reports. These self-reports raise concern about the combination; the study cannot establish the frequency of seizures.

Medsafe: symptoms of serotonin toxicity.

How do psychedelics work?

LSD’s acute psychedelic effects depend strongly on serotonin 5-HT2A receptors, while other receptor actions also contribute. Human studies show changes in cortical and thalamic connectivity. These findings suggest changes in how brain regions coordinate and process information. LSD findings should not be substituted for psilocybin findings. Preller et al. (2018); Preller et al. (2019).

Read Basic Psychedelic Neuroscience for a fuller explanation.

What does this mean for me?

Before deciding, work through the medical-screening questions. Use these questions to identify what needs further discussion with a qualified clinician. Bipolar disorder, a personal or family vulnerability to psychosis, significant suicidality, unstable mental health, important medical conditions or complex medication use need appropriate professional assessment.

Think about why you want this experience, how steady life feels right now, and who could help during and afterward. Consider what you hope to gain and whether the possible benefits are worth the risks for you. Waiting, choosing another form of support or deciding against it are valid choices.

Use the Preparation Guidebook to make a plan, the Sitter Guidebook to agree on support and boundaries, and the Integration Guidebook to reflect afterward. Take time afterward to consider what was useful and how you are feeling.

Johnson et al. (2008): human psychedelic research safety guidelines

Sources and limits

These pages bring Entheo’s descriptions of lived experience together with first-person accounts, qualitative interviews and clinical research. Qualitative studies help us understand how people experience and make meaning of these states. Clinical studies help address different questions, including medication interactions and physical risks.